Clostridium difficile

Updated March, 2008

Robert C. Owens, Jr, PharmD

Co-Director, Antimicrobial Stewardship Program

Department of Clinical Pharmacy, Division of Infectious Diseases

Maine Medical Center, Portland, ME

And Clinical Assistant Professor of Medicine, Department of Medicine

The University of Vermont, College of Medicine

Burlington, VT

Address: Maine Medical Center

Department of Clinical Pharmacy and Infectious Diseases

22 Bramhall Street, Portland, ME 04102

TEL: (207) 662-6294

E Mail: owensr@mmc.org

Stuart Johnson, M.D.

Staff Physician, Medicine Service

VA Chicago Health Care System, Lakeside Division &

Assistant Professor, Department of Medicine

Feinberg School of Medicine, Northwestern University, Chicago, IL

Address: Medical Service, VACHS - Lakeside Div.

333 East Huron, Chicago, IL 60611

TEL: (312) 469-2193, FAX: (312) 469-2313,

E Mail: stu-johnson@northwestern.edu

Dale N. Gerding, M.D.

Chief, Medical Service

VA Chicago Health Care System, Lakeside Division &

Professor, Department of Medicine &

Department of Laboratory Medicine & Pathology

Feinberg School of Medicine, Northwestern University, Chicago, IL

Address: Medical Service, VACHS - Lakeside Div.

333 East Huron, Chicago, IL 60611

TEL: (312) 469-2193, FAX: (312) 469-2313,

E Mail:  d-gerding@northwestern.edu

GENERAL DESCRIPTION

Microbiology Guided Medline Search

               Similar to other members of the clostridial family, Clostridium difficile is an anaerobic, gram-positive spore-forming rod-shaped bacterium. C. difficile characteristically forms subterminal spores. Most clinical laboratories that perform cultures on stool specimens for C. difficile use the selective CCFA (cycloserine-cefoxitin-fructose agar) media. Colonies of C. difficile on CCFA are flat, yellow, ground-glass appearing with a surrounding yellow halo. Culture of C. difficile in the laboratory and vegetative growth requires strict anaerobic conditions and pre-reduced media. Despite the meticulous conditions needed to cultivate C. difficile in the laboratory, sporulation allows this organism to be easily recovered from the environment of symptomatic patients and easily transmitted to susceptible patients.

Epidemiology Guided Medline Search

               This enteric pathogen has several unique epidemiological associations that are important to remember when considering therapeutic options. Institutionalization (e.g., hospitalization, residence in a long-term care or rehabilitation facility) and antimicrobial therapy are the best-documented risk factors for C. difficile-associated disease (CDAD) and reflect important steps in the pathogenesis of this disease. First, the association with healthcare facilities reflects the fact that C. difficile infection is acquired and that hospitals and other chronic-care institutions are major reservoirs for toxigenic strains of this organism (53). Where surveillance has been conducted, C. difficile diarrhea is found to be endemic in most tertiary hospitals and large outbreaks continue to occur (105). Stool culture surveillance of hospitalized patients indicates that C. difficile infection is extremely common and careful epidemiological typing studies have demonstrated that the majority of these infections are acquired exogenously (64,90,116). In fact, the risk of C. difficile acquisition is directly associated with the length of hospital stay (26). After three weeks of hospitalization in one study, one third of initially non-colonized patients were culture-positive, the majority of whom were asymptomatic (26).

               Second, this infection is seen almost exclusively in patients who are being treated with or who have recently received antimicrobial therapy (85). Disruption of indigenous bacterial flora resident in the intestinal tract by antimicrobial therapy (or, occasionally, by chemotherapy) is a critical element in the pathogenesis of Clostridium difficile-associated disease (142). Bacteria indigenous to the host’s intestinal tract prevent the establishment of most non-indigenous organisms and potential pathogens. This protection or "colonization resistance" can be overcome by enteric pathogens that employ specific virulence mechanisms (e.g. epithelial invasion by salmonellae). However, the identified virulence factors of C. difficile (toxins) are not sufficient themselves to allow C. difficile to overcome colonization resistance. In contrast, once C. difficile infection has been established, recovery of colonization resistance may be significantly delayed as evidenced by the high rate of recurrence following initially effective therapy (53,62). With the understanding that this infection is a complication of antimicrobial therapy, an important therapeutic intervention to remember is discontinuation of the offending drug or switching therapy to a potentially less predisposing agent such as (intravenous) aminoglycosides, vancomycin, or metronidazole (54). Simply discontinuing the offending agent may be the only intervention necessary in 15% of patients with C. difficile diarrhea (128). More commonly, C. difficile diarrhea becomes a prolonged illness unless it is recognized and treated with specific antimicrobial therapy.

               Geographically dispersed outbreaks caused by a more virulent and previously uncommon strain of C. difficile were first reported to occur in North America beginning in 2000 and most recently has been isolated in a variety of European countries (33, 87). The strain was characterized by several methods, including REA type (BI), polymerase chain reaction (PCR) ribotype (027), pulsed field gel electrophoresis (PFGE) type (NAP1), by toxinotyping studies as toxinotype III, and is commonly referred to as BI/NAP1 (87).  Similar to other strains of C. difficile, BI/NAP1 strains produce the two traditional toxins (A and B), but purportedly due to an 18-base pair tcdC gene deletion, BI/NAP1 strains hyperproduce both toxins (87).  Warny and colleagues (138) demonstrated that 16- and 23-times more toxin A and B, respectively, were produced compared with the common toxinotype 0 strain used as a control. In addition to the two traditional toxins, BI/NAP1strains also harbor a previously uncommon binary toxin gene (noted to be present in 6% of a historical sample of clinical isolates) (87). The structure and function of this toxin is similar to that of other binary toxins, such as iota toxin found in C. perfringens. Though patients infected with binary toxin positive strains of C. difficile trended towards having greater disease severity (11, 88), toxin A- and B-negative but binary toxin positive strains of C. difficile have been shown to be non-lethal in the classic hamster model of infection (55).

               As mentioned, BI/NAP1 strains of C. difficile belong to Toxinotype III which was previously rare, accounting for only 2-3% of C. difficile strains studied in a very large library of clinical isolates (87). Interestingly, other toxinotypes have been identified (e.g., XIV/XV and IX) during the current outbreak period (albeit with low frequency) in community-dwelling patients admitted to hospitals with severe disease (2,69). From the limited data available, they appear to be 64% and 85% related to the epidemic toxinotype III (BI/NAP1) strain, and contain the identified virulence markers (18-base pair tcdC gene delection and binary toxin) (2,69). This leads to the other emerging trend recently identified, that is, purported “community-acquired” CDAD (2). Several studies have investigated this emerging phenomenon. Common themes identified in these community-acquired cases is that a large proportion of patients (59-61%) did not admit to prior antimicrobial exposure and in this subset of patients that apparently lacked exposure to antimicrobials, proton pump inhibitor (PPI) use was more common (38,39,73). Other investigations have implicated the use of PPIs as an independent risk factor for CDAD in patients (5,31,69,98,102) while others have not (84,108). PPI use has been shown to cause colitis with or without specific histologic findings from biopsy specimens obtained during colonoscopy (forms of microscopic colitis such as lymphocytic and collagenous colitis) (112,131). Regardless of whether PPIs increase the risk of CDAD, clinicians should be mindful of the issue as colitis caused by PPIs may cloud the diagnosis of CDAD.

Bartlett JG.  Historical Perspectives on Studies of Clostridium difficile and C. difficile infection.  Clin Infect Dis 2008;46(Suppl 1):S4-S11.

Redelings MD, Sorvillo F, Mascola L. Increase in Clostridium difficile-related Mortality Rates, United States, 1999-2004.  Emerg Infect Dis 2007;13:1417-1419.

Bobulsky GS, Al-Nassir WN, et al. Clostridium difficile skin contamination in patients with C. difficile-associated disease. Clin Infect Dis 2008;46(3):447-50.

Review Article: McMaster-Baxter NL, Musher DM. Clostridium difficile: Recent Epidemiological Findings and Advances In Therapy.  Pharmacotherapy 2007;27(7):1029-1039.

Clinical Manifestations Guided Medline Search

               Infection with Clostridium difficile is associated with a wide spectrum of clinical manifestations ranging from asymptomatic colonization, non-specific watery diarrhea, pseudomembranous colitis to toxic megacolon (53). Typically, C. difficile diarrhea presents as watery diarrhea without visibly bloody stools during or shortly after antimicrobial therapy given for other indications. Fever, crampy abdominal pain, and leukocytosis are common. In the more severe manifestations of C. difficile disease patients may also present with abdominal distention and tenderness and systemic signs of toxicity. Abdominal radiographs may show thickened colonic wall, ascites, or marked colonic dilatation consistent with toxic megacolon. Endoscopic visualization of pseudomembranes in this setting is diagnostic of C. difficile disease. Ironically, patients with severe C. difficile disease often do not have diarrhea and are sometimes misdiagnosed with ischemic bowel or some other intra-abdominal catastrophe.

Laboratory Diagnosis Guided Medline Search

               Diagnosis of C. difficile disease in laboratory is based on detection of the organism or the presence of C. difficile toxins in the stool of symptomatic patients. Because colonization is common among hospitalized patients, detection of C. difficile by culture is only presumptive evidence of associated-disease. Detection of C. difficile toxins by cell culture assay or EIA is more specific for disease, but assessment of clinical symptoms is equally important in making therapeutic decisions. The cytotoxin assay for C. difficile toxins on cell cultures with neutralization by anti- C. difficile toxin antibodies has been replaced in most clinical laboratories with EIA tests for toxin A or toxins A and B. Although the results are more rapidly available with EIA, these tests are inherently less sensitive than the cell culture cytotoxin assay and a widely-disseminated toxin A-negative, B-positive C. difficile variant is not detected with the toxin A EIA kits (66).

Pathogenesis Guided Medline Search

               On the basis of epidemiologic observations we proposed that C. difficile disease is at least a "three-hit" disease (Figure 1) (63). Patients are made susceptible by exposure to antimicrobials (first hit) and if exposed to toxigenic strains of C. difficile (second hit) they may or may not develop symptomatic illness depending on the presence of another factor (third hit) which may relate to host susceptibility factors such as the immune response to toxin A (74) or virulence factors of the pathogen. The level of risk posed by the “first hit” likely varies between specific antimicrobials/antimicrobial classes depending on the inherent in vitro activity possessed by the antimicrobial against the infecting strain of C. difficile (second hit), the magnitude of collateral effects on indigenous bacterial flora, and the persistence of these effects once the antimicrobial has been discontinued. Although not the focus of any one particular study, it is interesting to note that clinical isolates of C. difficile collected during outbreaks for more than 3 decades have revealed the predominance of specific strains (e.g., restriction endonuclease analysis [REA] “J” type strains resistant to clindamycin in the 1970s-80s, REA “BI” type strains resistant to fluoroquinolones identified in the current outbreaks). Depending on the decade, certain antimicrobial classes were also more commonly used (e.g., clindamycin in the 1970s-80s, cephalosporins in the 1980s-90s, and fluoroquinolones in the 1990s-current times).

               C. difficile is a toxin-mediated disease and two, large, single-unit exotoxins are produced by most pathogenic strains. Toxin A, an enterotoxin produces fluid secretion, mucosal damage and inflammation in vivo and toxin B, a potent cytotoxin likely acts in concert with toxin A in the pathogenesis of C. difficile disease. These relatively homologous toxins probably have the same intra-cellular mode of action, but with different cell receptor specificity. Both toxins cause cell rounding as a consequence of glycosylation of small GTP-binding proteins of the Rho subfamily that are involved in the organization of the cell cytoskeleton (134). Subsequent pathogenic events may involve disruption of epithelial cell tight junctions and the pro-inflammatory effects of the toxins on leukocytes and monocytes.

Pepin J, Valiquette L, Gagnon S, Routhier S, Brazeau I.  Outcomes of Clostridium difficile-Associated Disease Treated with Metronidazole or Vancomycin Before and After the Emergency of NAP1/027.  Am J Gastroenterol 2007 Sep 27; [Epub ahead of print].

Johnson, S, Schriever C, Galang M, Kelly CP, Gerding DN.  Interruption of recurrent Clostridium difficile-Associated Diarrhea Episodes by Serial Therapy with Vancomycin and Rifaximin. Clin Infect Dis 2007;44:846-848.

SUSCEPTIBILITY IN VITRO AND IN VIVO Guided Medline Search In Vitro and In Vivo

               Although C. difficile isolates are highly resistant to some agents commonly implicated in precipitating C. difficile diarrhea (e.g., cephalosporins), other implicated antimicrobials (e.g. penicillin G and ampicillin) show marked activity against C. difficile in vitro (41). For other antimicrobial agents, different C. difficile isolates show marked heterogeneity in susceptibility (e.g., clindamycin and erythromycin). Therefore, factors other than antimicrobial susceptibility in vitro are important in determining the risk of C. difficile diarrhea. However, we recently showed that infection with a highly clindamycin-resistant C. difficile strain was associated with clindamycin use in epidemics of C. difficile diarrhea in four different hospitals around the United States (67). Differences in the reported rates of C. difficile diarrhea following clindamycin use may be partially explained by the presence or absence of these strains in the particular hospital environment. Similarly, the 8-methoxy fluoroquinolones demonstrated a high degree of in vitro activity against the most common strains of C. difficile isolated in the 1990s (87). The emergence of the previously uncommon BI/NAP1 strain was documented in several outbreaks starting in 2002. The BI/NAP1 strains were uniformly resistant to the “anti-anaerobic” 8-methoxy fluoroquinolones (gatifloxacin, moxifloxacin) as well as to all other fluoroquinolones while the 8-methoxy fluoroquinolones have retained activity against other C. difficile strains (87). When analyzing the in vitro susceptibility of C. difficile to agents used specifically for treatment of C. difficile diarrhea, one must also consider the achievable antimicrobial concentrations at the site of infection- the colonic mucosa.

Single Drug

               Table 1 lists the relative susceptibilities of C. difficile to various agents used to treat or proposed to treat C. difficile diarrhea. With the exception of rifampin, metronidazole is one of the most active agents available, and is bactericidal over a wide range of concentrations in vitro (78). Almost all isolates are susceptible to metronidazole concentrations of 1µg /ml or less with a typical MIC50 of 0.3 µg/ml (9,27,41,47,52). C. difficile isolates with elevated MIC values have been reported, but these isolates have been recovered from veterinary sources (61), the environment (21), or represent nontoxigenic strains (10,21) and their clinical significance is unknown. One C. difficile isolate with an MIC of >64 µg/ml has been reported in a patient with C. difficile diarrhea (143). Surveillance for resistance to current and investigational treatments among clinical isolates is an important consideration if we are to learn more about patterns of in vitro activity possessed by evolving strains of C. difficile.

               Tinidazole, a related compound, is slightly less active (9,68). C. difficile isolates are somewhat less susceptible to vancomycin (compared to metronidazole) with a typical MIC50 of 1 µg/ml and occasional isolates are found with MICs of 8 or 16 µg/ml (24,41). However, fecal vancomycin concentrations are typically in the 100 - 1000 µg/gm range with oral therapy (65) and there is no evidence that isolates with the higher MIC values exhibit clinical resistance. In vitro kinetic studies have demonstrated that whereas vancomycin was bactericidal for C. difficile at concentrations close to the MIC of the isolate, vancomycin exerted a bacteriostatic effect at higher concentrations typical of those levels demonstrated in the feces during therapy (78). This observation may partially explain the failure to eradicate C. difficile following initially effective therapy. In addition, recurrence of C. difficile diarrhea has not been associated with the development of vancomycin resistance (51). Teicoplanin, a related glycopeptide is somewhat more active in vitro than vancomycin (16,103).

               The Syrian golden hamster has been used to for susceptibility testing of C. difficile in vivo (12,47). C. difficile infection in the hamster is a model of human infection including the susceptibility to colonization at an early age that is lost with establishment of the indigenous flora (113). After two weeks of age, infection (colonization or disease) is totally dependent on antimicrobial exposure. The main site of disease in the antibiotic-treated hamster is the cecum, an organ in rodents that is proportionately much larger than in humans, but which serves functions similar to that served by the human colon, the site of disease in humans. Although the results of in vivo testing are dependent on the strain of C. difficile used and the experimental design (126) several common themes have been documented by most investigators. First, the mortality of untreated C. difficile diarrhea in hamsters is close to 100%. Second, all antimicrobial agents that have shown treatment efficacy in vivo can also be used to precipitate the disease in hamsters. Third, while both vancomycin and metronidazole protect infected hamsters during therapy, once therapy is discontinued the organism and cytotoxin becomes detectable in the stool and the animals succumb within 2 to 9 days (12,47). When strict animal housing/handling methods have been employed in these experiments the mortality rates drop suggesting that these animals are still susceptible following vancomycin treatment and that conventionally housed hamsters re-acquire the organism from their environment (47). More recently vancomycin was shown to protect hamsters in a dose-dependent manner and Tiacumicin B, an investigational macrolide was more active than vancomycin in these experiments (126).

Combination Drugs

               Rifampin has been tested in combination with various agents against C. difficile in vitro. Although the rifamycin derivatives (e.g., rifampin, rifaximin, rifalazil) are the most active drugs tested in vitro, resistance appears to develop quickly (43). When defined as a 4-fold reduction in the MIC for both agents, one study demonstrated synergy with the rifampin/ metronidazole combination in 68% of isolates tested, with rifampin/ vancomycin in 38% of isolates and with vancomycin/metronidazole in 68% of isolates (43). Another study demonstrated only partial synergy with rifampin/metronidazole in 38% of isolates tested and with rifampin/vancomycin in 4% of isolates using a fractional inhibitory concentration (FIC) index of 0.51 to 0.75 as the definition of partial synergy (8). However, full synergy (FIC <0.50) was demonstrated with rifampin/bacitracin in 85% of isolates tested. A study evaluating the combination of metronidazole and rifampin did not result in improved outcomes over metronidazole monotherapy for primary episodes of CDAD (75). Thus, clinical translation of in vitro synergy results remains difficult to interpret.

ANTIMICROBIAL THERAPY Guided Medline Search

[McMaster-Baxter NL, Musher DM. Clostridium difficile: Recent Epidemiological Findings and Advances In Therapy.  Pharmacotherapy 2007;27(7):1029-1039.]

General Considerations and Treatment for 1st and 2nd Episodes

               As is shown in Table 2, metronidazole, vancomycin, teicoplanin, and fusidic acid have all demonstrated >90% efficacy in randomized comparative trials of C. difficile diarrhea treatment. The most clinical experience has been with vancomycin and metronidazole. Metronidazole, unlike vancomycin, is well-absorbed and fecal concentrations are low or absent in treated patients without diarrhea (7,60,65). However, bactericidal fecal concentrations are present in patients with C. difficile diarrhea and decrease as the diarrhea improves, suggesting that metronidazole may diffuse from the serum compartment directly through inflamed colonic mucosa or that increased intestinal transit time results in reduced absorption (18).

               Although vancomycin was originally considered the drug of choice by several experts, metronidazole is the preferred first line agent for most cases of CDAD for several reasons. First, the efficacy of metronidazole has been confirmed in a subsequent prospective randomized trial demonstrating high cure rates and similar clinical recurrence rates when compared with vancomycin and teicoplanin (139). The earlier prospective comparison of metronidazole and vancomycin (128) has been criticized because patients with positive stool cultures and negative stool toxin assays were included in the study and several reviews have cautioned that metronidazole be reserved for less severe cases of C. difficile diarrhea (45). Cure and recurrence rates in the more recent study (92) and in the earlier prospective study (128) were the same when patients with pseudomembranous colitis documented by endoscopy were analyzed separately suggesting that severity of disease does not influence the response to metronidazole. Another report also documented similar cure and recurrence rates, however, the duration of symptoms in this retrospective study was shorter in patients treated with vancomycin than for those who received metronidazole [3 vs. 4.6 days, respectively] (141). Neither of the two prospective studies showed any difference in the time to response between patients treated with these two agents (125,128). Because the response rates to either metronidazole or vancomycin are so high, a prospective study of enormous patient size would be necessary to demonstrate any subtle differences in clinical efficacy. The clinical experience with metronidazole for C. difficile diarrhea was reviewed at one institution over a 10-year period in which metronidazole was emphasized as first-line therapy (70%, 13%, and 17% of patients received metronidazole, vancomycin, and no treatment, respectively) (101). The drug intolerance rate, treatment failure rate, and recurrence rate for 632 metronidazole-treated patients was 1%, 2%, and 6%, respectively.

               Second, metronidazole is the least expensive treatment for C. difficile diarrhea at a cost of $4.00 for a 10-day treatment course (250 mg four times daily) compared to $175.00 or $873.00 for a 10-day course of vancomycin (125 mg or 500 mg four times daily) (local Chicago, IL pharmacy costs). Third, concern over the increase in vancomycin resistance among enterococci and, potentially, other important hospital-acquired pathogens has led to the recommendation that vancomycin use be limited. In particular, the Hospital Infection Control Practices Advisory Committee (HICPAC) has suggested that oral vancomycin be reserved for the treatment of patients who fail to respond to metronidazole or in severe, potentially life threatening illness (42). This recommendation has, in general, received wide-spread acceptance and most experts now recommend metronidazole as the initial specific agent of choice except for particular situations (44,53). Long term follow-up of >700 women who received metronidazole for vaginal trichomoniasis did not demonstrated increased cancer-related morbidity or mortality (14) despite evidence of carcinogenic potential in some rodent studies. The safety of metronidazole in children has not been proven (44) and metronidazole is a pregnancy category B drug. Despite having no FDA approval for this indication, we believe that metronidazole should be considered the drug of choice for C. difficile diarrhea.

               Vancomycin was the first effective therapy for C. difficile diarrhea and has been the drug to which all subsequent therapies have been compared (45). Cure rates close to 100% for vancomycin at a dosage of 500 mg given orally three to four times daily for 10 days have been documented in all the prospective studies reported (Table 2). This response rate drops to 75% when the regimen is decreased to 125 mg orally four times daily for 5 days (Table 2). However, there were no treatment failures when the 'lower dose' vancomycin regimen (125 mg four times daily) was given for 10 days (46). Despite the predictably high fecal levels achieved and its remarkable clinical efficacy, ~15% of treated patients will still have a recurrence (Table 2). Teicoplanin has demonstrated efficacy similar to that achieved with vancomycin and metronidazole in two prospective clinical studies when studied at two different doses given twice a day for 10 days (35,139). Fusidic acid has been studied prospectively and although similar, high cure rates were demonstrated, the clinical recurrence rate was higher than for those treated with teicoplanin (139). Fusidic acid was also associated with at higher rate of side affects (gastrointestinal discomfort) compared with vancomycin and teicoplanin therapy. Clinical cure rates and C. difficile eradication rates with bacitracin are somewhat lower than with vancomycin (40,144) and bacitracin should be considered as a second line agent in the treatment of C. difficile diarrhea. Treatment with the ion-exchange resin, colestipol, is clearly inferior to the agents described above (93) and is not recommended for initial treatment.

               The optimal dosage of most effective treatments for C. difficile diarrhea have not been determined but duration of therapy for 10 days appears necessary to achieve cure rates of 90%. Based on the available data we recommend the following dosages; metronidazole 250 mg orally four times daily or 500 mg three times daily and vancomycin 125 mg orally four times daily. Further studies will be necessary before teicoplanin (1,139) and fusidic acid (30,139) dosage recommendations can be made. All therapies should be administered orally and antiperistaltic agents should not be administered. An early controlled trial indicated that phenoxylate-atropine (Lomotil) used alone was deleterious to patients with C. difficile diarrhea (100) and anecdotal reports suggest that its use may predispose to toxic megacolon (29,50). Loperamide has also been implicated in toxic megacolon (135). A recent retrospective study did not demonstrate any different response in patients who received antimotility agents (usually loperamide or codeine phosphate) in conjunction with specific therapy (141), but carefully designed prospective studies need to be conducted before any general recommendations can be made regarding the use of antimotility agents for C. difficile diarrhea.

               Historically, patients with primary infection due to C. difficile (1st episode) who respond to therapy but develop a 2nd episode have responded to retreatment with the same therapy, an approach also endorsed by previous guidelines (53). A recent study conducted in the era of BI/NAP1 reiterated that 1st and 2nd episodes of CDAD can be effectively treated with metronidazole (107).  However in this study, regardless of choice of therapy (metronidazole or vancomycin), complication rates were higher than previously reported for either drug. Another recent study evaluated the approach of combining rifampin with metronidazole versus monotherapy with metronidazole for 1st episode cases of CDAD (Table 2) (75). This study showed no incremental benefit gained by the addition of rifampin to metronidazole (75).  Also, recent studies utilizing metronidazole as the comparator agent in trials of investigational therapies such as nitazoxanide have demonstrated non-inferiority of the newer therapies to metronidazole (Table 2) (97).  In addition, vancomycin’s efficacy has been re-evaluated as a result of being used as a comparator for investigational therapies such as tolevamer. The efficacy of vancomycin was similar to high-dose tolevamer and superior to low-dose tolevamer (Table 2). Although these recent studies involved relatively small numbers of patients and severely-ill patients were excluded from participation, they do provide some insight into the efficacy of these established treatment options relative to newer agents.

               Caveats to the general principle of utilizing the same therapy to manage 1st and 2nd episodes of CDAD which may influence the clinician’s decision to use a different agent for the 2nd episode include the presence of markers for severe disease and whether or not the gastrointestinal tract is functioning (e.g., presence of ileus, toxic megacolon). Treatment options for fulminant CDAD and for patients with compromised gastrointestinal function necessitating alternative therapy are discussed later in this chapter.

Recurrent CDAD (≥3rd episode)

               Recurrent disease remains a challenge for clinicians, researchers, and particularly for the patients themselves. It is apparent from Table 2 that most people respond to treatment for C. difficile diarrhea. Recurrence of diarrhea after initially effective therapy is extremely common, however, occurring at rates of 5 to 30% regardless of the initial treatment regimen, similar to the experience with the hamster model of C. difficile diarrhea. As mentioned above, the mechanism of diarrhea recurrence may be different following metronidazole or vancomycin therapy as a result of decreasing metronidazole fecal levels on resolution of diarrhea or the bacteriostatic effect of vancomycin on C. difficile at the high concentrations achieved during therapy (78). In addition, diarrhea recurrence may be due to relapse of the original infecting strain or due to exogenous reinfection with a new strain (62). There is no evidence that recurrence or failure of initial treatment response in the case of metronidazole is due to acquisition of resistance to the initial therapeutic agent (117). A small group of patients suffer multiple recurrences of C. difficile diarrhea, frustrating to the physician as well as to the patient. Typically, these patients respond promptly to treatment after each recurrent episode but redevelop symptoms and positive stool assays within one to two weeks after discontinuation of treatment. As previously mentioned, nearly all cases of C. difficile diarrhea are precipitated by antimicrobial disruption of normal intestinal flora. It is possible that the specific agent used for treatment of the initial episode of diarrhea is the precipitating agent for the recurrent episode.

               Several strategies have been explored for managing patients with multiple recurrences (Table 3). When interpreting the efficacy of these strategies, one must consider a number of pitfalls that cloud the interpretation of the efficacy of the intervention and limits the widespread extrapolation of the results to a broader population. Chief among these are the introduction of type 2 error and investigator bias due in part to small sample sizes and the open-labeled nature of these case reports, case series, and in some cases clinical trials. This being stated, recurrent CDAD remains a significant challenge resulting in nearly continuous treatment with vancomycin in a small number of patients. For these patients, it is helpful to have options. Discussed below is a distillation of studies and case series that may be considered for recurrent CDAD.

               Of the biotherapeutic approaches, treatment with the yeast Saccharomyces boulardii is probably the best studied. In the initial report of 13 patients with multiple diarrhea recurrences who received vancomycin for 10 days and S. boulardii for 28 days, 11 patients had no further recurrences (124). A subsequent randomized, placebo-controlled study showed that S. boulardii in combination with standard therapy was more effective than standard therapy alone in preventing recurrences in patients who had a history of more than one C. difficile diarrhea episode (91). A more recent study in which the standard therapy and therapeutic dose was stratified showed a significant decrease in recurrent episodes among patients treated with high-dose vancomycin (2 gm/day) and S. boulardii compared with to high-dose vancomycin and placebo (125). Neither low-dose vancomycin or metronidazole with or without S. boulardii was effective. Still today, the data to support the use of lactobacillus-containing and S. boulardii-containing regimens are poor and conflicting. The best study supporting the use of S. boulardii (91) did not convince the Food and Drug Administration to approve it for this use (13).  A recent meta-analysis suggested that probiotics are effective; however, because of the heterogeneity of study methodologies and patient populations, it is not scientifically possible to conduct a meta-analysis of the probiotic literature. Critical examinations of an earlier meta-analysis (32) of probiotic use cast similar doubt upon the authors’ conclusions for related reasons (15). A systematic review of probiotic efficacy indicated that the current literature does not support the use of probiotics for CDAD (37). Moreover, the literature is evolving to demonstrate that the so-called non-pathogenic strains of the various fungi and bacteria used in the currently marketed probiotics have caused numerous cases of bacteremias due to Lactobacillus species and fungemias due to S. boulardii in both immunocompetant and immunocompromised hosts (25,42,79,114).

               Other, non-antimicrobial, biotherapeutic approaches tested in open trials include treatment with rectal infusions of feces from normal hosts (20,118) and the infusion of a mixture of bacteria simulating a normal flora (133). A recent review of the eight reports of this approach involving instillation of feces or fecal bacteria was optimistic, indicating a good cure rate without recurrence for most patients (19). Despite the aesthetic concerns of this approach and the potential concern for transmission of other infectious agents, investigators have tried to refine this method using different carrier suspensions and modes of infusion. An additional novel approach that was partially successful in two patients was introduction of a non-toxigenic strain of C. difficile (119).

               Antimicrobial approaches that have been studied in small open trials include combination therapy with vancomycin (125 mg PO qid) and rifampin (600 mg PO bid) given for 7 days (23) and a study of 163 patients evaluating a mixture of strategies including treatment with different vancomycin doses for 10 days, treatment which was followed by tapering doses for a mean of 21 days, or treatment with vancomycin (or no treatment) immediately followed by pulsed dosed vancomycin (a single dose of 125, 250, or 500 mg given every 3 days) for a mean of 27 days (130). High total daily dose (2g/d) vancomycin for 10 days performed slightly better than traditional total daily dose (500 mg/d) vancomycin in terms of reduced recurrence rates. Treatment followed by tapered vancomycin and treatment followed by pulsed vancomycin resulted in a significantly reduced recurrences when compared with treatment alone, with the latter regimen being associated with the least amount of recurrences. Tedesco and colleagues (130) also studied vancomycin tapered regimens in 22 patients. The regimen consisted of: week 1 (500 mg/d), week 2 (250 mg/d), week 3 (125 mg/d), weeks 4-6 (pulsed dosed vancomycin 125 mg every 3 days). Collectively, these descriptive studies demonstrate that tapered and pulsed dosed vancomycin regimens seem to be effective in reducing recurrences and large scale prospective studies are warranted. Metronidazole has also been studied in a pulsed and tapered regimen but too few patients were evaluable to draw any conclusions. The concept of the pulsed regimen takes advantage of the fact that our current treatments (e.g., vancomycin, metronidazole) are only effective against vegetative forms (but not spore forms) of C. difficile. By allowing for a relatively antibiotic-free period in the gastrointestinal tract, it is theorized that spore forms will recrudesce into vegetative forms rendering them susceptible to subsequent therapy.

               Cholestyramine, an anion-exchange binding resin has also been anecdotally reported as useful in this setting (71,95,111,129). However, the efficacy of anion-exchange binding resins in the treatment of primary C. difficile diarrhea has been poor when evaluated under more rigorous conditions (Table 1). The only placebo controlled trial that has evaluated the toxin binding capability of anion exchange resins was conducted using colestipol, which demonstrated that these agents were comparable to placebo in terms of reducing fecal excretion of C. difficile toxins (94).  Animal models have confirmed cholestyramine’s poor toxin binding affinity relative to other toxin binding compounds (72).  Cholestyramine does, however, bind to a variety of drugs (99),  including the very treatments themselves (e.g., vancomycin), resulting in a reduction of biological activity in stool (127). Based on the lack of efficacy data to support the use of cholestyramine and the potential for deleterious effects when combined with oral treatments for C. difficile-associated disease, their use cannot be recommended. Intravenous administration of immune globulin (IVIG) may also benefit a subgroup of patients with multiple recurrences of C. difficile diarrhea (59,77,137). In two of the studies, patients had low levels of serum anti-toxin A IgG (77,137) and the patient in the third study had selective IgG1 deficiency (59). The largest study published to date of IVIG was a retrospective, observational evaluation of 14 patients (92).  Six of 14 patients responded clinically, and no relapse occurred within the timeframe reported. The doses used ranged from 150-400 mg/kg administered as a single-dose (one patient received a second dose). The median response time was 10 days. In another study, 3 of 5 patients treated with doses of IVIG between 300 to 500 mg/kg (usually 400 mg/kg), were deemed successes, with resolution occurring within 11 days (140).  An upside to IVIG is that it may provide therapeutic option for patients with severe/relapsing disease where no other therapeutic options are available. Unfortunately, marginal efficacy, lack of data regarding the optimal dose, cost (~$U.S. 1,500/dose for a 70kg patient) (132) and frequent shortages are significant disadvantages (132). 

               One report suggested that whole bowel irrigation with a polyethylene glycol solution (Golytely) followed by a course of vancomycin was successful in terminating multiple recurrences of C. difficile colitis in two young children (80). A more recent report combined Golytely lavage with administration of donated feces directly through a colonoscope to all segments of the colon (110). The theoretical advantage of this refinement over previous fecal replacement strategies was a more thorough reduction of the resident flora and recolonization of the entire colon. Finally, no treatment with careful observation has also been advocated in selected patients (53).

               Recently, 8 patients ranging in age from 43-88 years with 4-8 prior episodes of CDAD and receiving between 79-372 total days of treatment were placed on an unconventional regimen as described momentarily.  In these patients, a variety of treatment strategies had been previously attempted, including combinations of standard therapy (metronidazole or vancomycin) and rifampin, probiotics, tapered or pulsed vancomycin regimens. Although diarrhea would cease for a period of time, symptoms would invariably return (mean 10.5 days, range 1-59 days). These patients were treated until symptoms resolved and then immediately started on rifaximin 400 to 800 mg daily (divided into 2 to 3 doses) for 2 weeks. In this small sample, 7 of 8 patients remained symptom free for a range of 51 to 431 days. One patient was reported to have a recurrent episode, was retreated with a 2-week course of rifaximin and has remained symptom free for 9 months. One patient developed high-level resistance during therapy (MIC values for the pre- and post-therapy isolates were 0.0078 µg/mL and >256 µg/mL, respectively), although the patient remained asymptomatic. The results of this case series are promising for a very frustrating clinical problem facing many clinicians today; however, it should be kept in mind that this use of rifaximin is considered “off-label” (rifaximin is not approved by the FDA for the treatment of CDAD) and that resistance was clearly documented to occur during exposure to rifaximin.

Fulminant CDAD: The hypervirulent C. difficile strain (BI/NAP1) has been associated with more severe disease by some investigators (2,33,87,106,109). A retrospective observational study that included infection with BI/NAP1 strains demonstrated that whether metronidazole or vancomycin was used for 2nd episode cases, the complication rates were higher for both options compared with historical controls (106). However, if severe CDAD is suspected, several determinations should be made. First, is ileus or toxic megacolon suspected?  If so, see section below and early surgical consultation must be emphasized. For severe CDAD (defined as elevated white blood cell count, ascites, and/or hypotension) but in the absence of ileus or toxic megacolon, oral vancomycin may be considered for initial therapy and is recommended by some experts. The patient should be monitored daily for response to therapy, including the number and consistency of bowel movements as well as for markers necessitating surgical evaluation.

Severe Ileus/Toxic Megacolon: The most serious manifestation of C. difficile disease is toxic megacolon which, paradoxically, may present without diarrhea (96,101). Treatment of patients with toxic megacolon or severe illness is difficult and controversial but several attempts have been made to achieve effective antimicrobial concentrations at the site of infection when the oral route is compromised. Some authors advocate treatment with intravenous metronidazole or with intravenous vancomycin at dosages 2 grams per day, placement of a long catheter in the small intestine and instillation of vancomycin (122). Another approach is to administer vancomycin by rectal enema (56,101,104). A strategy used successfully at one institution in six patients with severe ileus included vancomycin administered by nasogastric tube and by retention enema plus intravenous metronidazole (Table 4) (101). If these approaches are unsuccessful surgical intervention or colonic decompression should be considered (see Adjunctive Therapy).

[McMaster-Baxter NL, Musher DM. Clostridium difficile: Recent Epidemiological Findings and Advances In Therapy.  Pharmacotherapy 2007;27(7):1029-1039.]

When Oral Therapy Is Not Possible: Although several options exist for the treatment of C. difficile diarrhea (Table 2), all well-studied regimens employ oral therapy. When the oral route is compromised, intravenous therapy may be considered. Colonic concentrations of vancomycin are negligible after intravenous administration and there is little support for this option. Fecal concentrations of metronidazole, however, are similar when metronidazole is given orally or intravenously in the setting of acute C. difficile diarrhea (18). Anecdotal experience supports intravenous metronidazole therapy for C. difficile diarrhea (18,57,70). A recent retrospective review of 10 patients who received at least two days of intravenous metronidazole as the initial therapy for acute C. difficile colitis in whom oral therapy was not possible showed symptomatic improvement in the majority of patients during therapy without subsequent complications requiring surgical intervention (49). A randomized, prospective study is needed, but this therapy alone may be inadequate in patients with severe adynamic ileus (58). Therefore, in patients with severe manifestations of C. difficile disease, other methods to ensure effective antimicrobial concentrations at the site of infection should also be considered (Table 4).

(Printable Version of Antimicrobial Therapy for Clostridium difficile)

ADJUNCTIVE THERAPY Guided Medline Search

               In patients who have failed medical therapy, two other approaches may be considered. A recent retrospective study reported the experience in one institution with early decompressive colonoscopy in patients with severe pseudomembranous colitis (121). After decompression of the colon in eight patients with ileus and toxic megacolon, a fenestrated tube was positioned over a guidewire and the tube was perfused with a vancomycin solution. Despite the high mortality in this group of patients, this treatment was effective in treating the colitis in most patients and complications such as perforation were not seen.

               Surgical intervention is indicated in patients with toxic megacolon who are not responding to medical treatment or when colonic perforation is suspected (96). Colonic diversions and partial colectomies have been performed but mortality is high (96). Although efficacy has been difficult to assess, subtotal colectomy with sparing of the rectal stump (total abdominal colectomy) appears to be the preferred surgical option (29,96). The experience with colectomy for fulminant C. difficile colitis at one medical center over a 12-year period was recently reviewed and included 64 patients who died or underwent colectomy (33). The mortality in patients who underwent colectomy in this series was 57% and the authors point out the importance of timing of the intervention. Significant predictors of death after operation were preoperative vasopressor requirements and age. Identifying patients who will benefit from colectomy is difficult, but intervention before marked hypotension is present appears important. One clue to impending fulminant colitis is a rapidly rising leukocytosis with band forms. Previous surgical procedures, prior episodes of C. difficile diarrhea and immunosuppression, particularly lung transplantation were common in these patients. The most helpful diagnostic test in this series was abdominal computed tomography (CT), which was useful even without the use of contrast agents.

Juang P, et al.  Clinical outcomes of intravenous immune globulin in severe clostridium difficile-associated diarrhea.  Am J Infect Control 2007;35:131-137.

ENDPOINTS FOR MONITORING THERAPY Guided Medline Search

               The only endpoint useful in monitoring therapy for C. difficile diarrhea is clinical evaluation of patient symptoms. Treatment with specific therapy (Table 2) should be given for 10 days and discontinued. Although no data are available, some clinicians will continue specific therapy for longer than 10 days if the precipitating antimicrobial cannot be discontinued. Continuation of therapy beyond that recommended in those who have responded to treatment is dangerous, for the treatments themselves (metronidazole and vancomycin) are not active against spore forms of C. difficile, they are destructive to normal commensal flora, and these treatments themselves have been implicated as causes of CDAD. In at least one author’s opinion, CDAD should be treated episodically and there is no role for “prophylaxis”. If the patient does not respond after 5 to 6 days of specific therapy, an empirical switch to an alternate drug may be entertained (e.g., vancomycin for metronidazole), but the initial diagnosis should also be reconsidered. Positive stool cultures for C. difficile at the completion of therapy is moderately predictive of recurrence (136), but it is strongly recommended that stool cultures and toxin assays not be performed if the patient’s symptoms have resolved (53). Positive test results alone often lead clinicians to inappropriately prolong therapy or switch therapy to a different agent. Clinical recurrences occur frequently, but final resolution of symptoms in most patients likely depends on reestablishing the normal colonic flora and further antibiotic therapy potentially delays the recovery of the normal flora. In addition, attempts at eradication of the carrier state with metronidazole is ineffective and only temporarily effective with vancomycin and, therefore, treatment of asymptomatic patients is not recommended  (65).

Pepin J, Valiquette L, Gagnon S, Routhier S, Brazeau I.  Outcomes of Clostridium difficile-Associated Disease Treated with Metronidazole or Vancomycin Before and After the Emergency of NAP1/027.  Am J Gastroenterol 2007 Sep 27; [Epub ahead of print].

INVESTIGATIONAL MANAGEMENT OPTIONS

Nitazoxanide: (Alinia®, Romark Pharmaceuticals) is currently approved for the treatment of a variety of parasitic diarrheal illnesses. Nitazoxanide has demonstrated in vitro activity against C. difficile and has undergone a comparative evaluation as a 500 mg twice daily regimen given for either 7- or 10-days versus metronidazole 250 mg 4 times daily for 10 days (97). This was a randomized, double-blind study in adult hospitalized patients, enrolling between 36-40 patients in each of the 3 treatment arms. Response rates after 7 days of treatment and 31 days after beginning treatment for metronidazole, nitazoxanide-7 days, and nitazoxanide-10 days were 82.4, 57.6%; 90, 65.8%; and 88.9, 74%, respectively (97).

Rifaximin: (Xifaxan®, Salix Pharmaceuticals), a non-absorbed rifamycin derivative, is approved for use in traveler’s diarrhea (but not infection due to C. difficile) and has good in vitro activity against C. difficile. In vitro resistance, however, already exists to this compound (3% of strains recently tested) (52). As discussed in the recurrent disease section, the “rifaximin chaser” has been shown to be useful in a limited number of patients with vancomycin-dependent recurrent disease.

PAR-101: Also known as OPT-80, PAR-101 is an 18-membered macrocyclic compound with limited activity against intestinal flora but is highly active against C. difficile (82). Similar to other novel treatments for C. difficile, PAR-101 is minimally absorbed, demonstrates low minimum inhibitory concentration values against C. difficile, and has been shown to be effective in animal models of CDAD (4).

Ramoplanin: (Oscient Pharmaceuticals) was evaluated in a phase II trial compared to vancomycin but has not undergone further evaluation. Ramoplanin demonstrated similar efficacy compared to vancomycin in the clindamycin-induced C. difficile infection model in hamsters (48).

Tolevamer: (Genzyme Corporation) is a liquid polystyrene preparation that binds to C. difficile toxins A and B. The results of a randomized, double-blind, active-controlled phase II study in patients with mild to moderate CDAD were recently reported (83). Two doses of tolevamer (3g/day, 6g/day) were compared with vancomycin (125mg q 6h). Tolevamer 6g/day, but not 3g/day, demonstrated non-inferiority to vancomycin, with a trend toward reduced recurrence in the high-dose tolevamer arm (P=0.05) (83). Because tolevamer lacks antimicrobial activity, commensal microbiota are not impacted and its therapeutic effect is attributed to toxin neutralization. Overall, tolevamer was well tolerated except for hypokalemia, which occurred in 23% of the tolevamer treated patients versus 7% of vancomycin recipients, (P<0.05). As a result of this study, a new liquid formulation of tolevamer that allows for higher doses to be administered and that contains potassium as a counter ion to minimize hypokalemia is progressing through development.

Toxoid Vaccine: (Acambis Pharmaceuticals) is in early developmental stages at the current time. In a very small study of three patients with recurrent CDAD (patients requiring 7-22 months of continuous vancomycin therapy), a parenterally administered C. difficile vaccine containing toxoid A and toxoid B was evaluated (123). Two of the 3 patients demonstrated increased IgG antitoxin A antibodies (3- and 4-fold increases), while an increased IgG antitoxin B antibody response was observed (20- and 50-fold). All three patients discontinued use of vancomycin without further recurrence.

Non-Toxigenic Strains of C. difficile: Other risk reducing methods that have not yet been proven effective, but hold substantial promise in the future include biological prophylaxis of patients receiving antimicrobials through administration of non-toxigenic strains of C. difficile which has been proven to be successful in the hamster model of C. difficile disease and in a limited number of patients (115,119). In addition, vaccines and immunotherapies may also provide preventative options to high risk patients pending the outcomes of ongoing clinical trials.

PREVENTION Guided Medline Search

Infection Control Measures

               Strategies employed to control and prevent C. difficile diarrhea can be classified into methods that prevent transmission and methods that reduce the risk of clinical illness if the patient is exposed. Numerous methods have been proposed or employed in attempts to prevent transmission including barrier precautions, gloving, handwashing, environmental disinfection, replacement of electronic rectal thermometers and treatment of asymptomatic carriers of C. difficile. Although handwashing and possibly barrier precautions may be effective, data showing decreased rates of C. difficile diarrhea have only been demonstrated for glove use (64), replacement of electronic thermometers with single use disposables (22), and replacement of quaternary ammonium solution with unbuffered 1:10 hypochlorite solution for environmental disinfection (6,86). Handwashing with soap and water is preferred over alcohol hand rubs, as recommended by the CDC, when caring for patients with CDAD during outbreaks. Differences in hand-to-hand transmission of C. difficile were noted between the two methods favoring the use of handwashing with soap and water over alcohol hand rubs (76).  It is important to note that alcohol hand sanitizers have improved compliance with hand hygiene policies in healthcare settings and should continue to be encouraged when caring for patients without C. difficile. However, complete prevention of transmission may be impossible because of compliance with barrier methods, practical issues with hypochlorite disinfectants, and other unidentified factors. Nonetheless, a “bundled” approach to the prevention of CDAD (analogous to the ventilator-associated pneumonia prevention bundle recommended by the IHI, for instance) is most likely necessary to impact institutional rates of CDAD due to the multifactorial nature of C. difficile’s transmission dynamics. Since many patients are either treated as outpatients or are initially treated in an acute care facility and then discharged when clinically improved, patients should be advised regarding proper hand hygiene and environmental cleaning (with regard to their bathrooms at home).

Antimicrobial Stewardship

               Even if prevention of transmission is incomplete, methods that reduce risk of disease are often more easily implemented and potentially more effective. Control of antimicrobial use, and control of clindamycin in particular, has been dramatically successful in reducing rates of C. difficile diarrhea and interrupting local epidemics caused by J-type C. difficile strains. Restriction of clindamycin in these settings was repeatedly shown to be effective (28,105) where heavy clindamycin use and the presence of highly clindamycin-resistant strains was likely (67). Control of second and third generation cephalosporins can also be effective, particularly when replaced with apparent less-predisposing antimicrobials, such as piperacillin-tazobactam (120). In contrast to previous outbreak strains, BI/NAP1 demonstrates variable susceptibility to clindamycin and uniform resistance to fluoroquinolones (69,81,87) In addition to clindamycin and cephalosporins, fluoroquinolones have emerged as significant risk factors for CDAD due to BI/NAP1 strains (69,81,108). Currently, fluoroquinolones are among the most commonly prescribed antimicrobials in the United States to both inpatients and outpatients. Programs that encourage diversity in antimicrobial use, and reduce unnecessary use (by eliminating redundant antimicrobials, promoting shorter courses of therapy, using a “careful watch and wait” approach to outpatient upper respiratory tract infections, as examples) may be part of a “bundled” strategy for healthcare facilities or clinics to adopt. A recent Cochrane Review highlighted that one of the major benefits to antimicrobial stewardship interventions was an association with reduced CDAD rates (34). Guidelines for establishing a programmatic approach to enhance antimicrobial stewardship were recently published jointly by the IDSA and SHEA (36).

COMMENTS

               In summary, it should be remembered that C. difficile diarrhea and colitis are complications of antimicrobial therapy and that the indigenous bacterial flora of the intestinal tract provide a critical element of host defense against this pathogen. Once C. difficile diarrhea is suspected on clinical grounds (patient has recently received antimicrobial therapy, particularly if they are or have been recently hospitalized) the following general principles of therapy should be considered (53). First, discontinue the offending antibiotic, if possible. This may be the only intervention necessary in some patients (101,128), but with the increasing disease severity it is likely to not be the only intervention necessary. Patients should be started on empirical therapy if the clinical suspicion for CDAD exists while awaiting the results of toxin assay results. If the patient is hospitalized, barrier precautions and isolation should be instituted, and handwashing with soap and water should take place before and after patient contact. Second, specific therapy should be administered orally. Third, nearly all patients respond to specific therapy, but the mean time to response is 2 to 4 days (Table 2), and maybe slightly longer if metronidazole is used. Fourth, treat for 10 days and do not perform test of cure assays if the patient has responded. Finally, until better data become available, avoid antiperistaltic agents and proton pump inhibitors (if at all possible).

TABLES

Table 1.  In Vitro Susceptibility of Clostridium difficile to Potential Therapeutic Antimicrobial Agents (Data Selected from Representative Studies).

Table 2.  Randomized, Comparative Trials of Oral Therapy for Clostridium difficile Diarrhea*   [Download PDF]

Table 3.  Empirical treatment strategies for patients with multiple recurrences of C. difficile diarrhea

Table 4. Empirical Treatment Protocol for Clostridium difficile-Infected Patients with Severe Ileus*

Table 5.  Potential Future Treatment Options

Figure 1: Three Hit Disease

REFERENCES

1. Treatment of Clostridium difficile associated diarrhea and colitis with an oral preparation of teicoplanin; a dose finding study. The Swedish CDAD Study Group. Scand J Infect Dis 1994;26(3):309-316. [PubMed]

2. Severe Clostridium difficile-associated disease in populations previously at low risk--four states, 2005. MMWR Morb Mortal Wkly Rep 2005;54(47):1201-1205. [PubMed]  

3. Aas J, Gessert CE, Bakken JS. Recurrent Clostridium difficile colitis: case series involving 18 patients treated with donor stool administered via a nasogastric tube. Clin Infect Dis 2003 ;36(5):580-585. [PubMed] 

4. Ackermann G, Loffler B, Adler D, Rodloff AC. In vitro activity of OPT-80 against Clostridium difficile. Antimicrob Agents Chemother 2004 June;48(6):2280-2282. [PubMed]

5. Al-Tureihi FI, Hassoun A, Wolf-Klein G, Isenberg H. Albumin, length of stay, and proton pump inhibitors: key factors in Clostridium difficile-associated disease in nursing home patients. J Am Med Dir Assoc 2005;6(2):105-108. [PubMed]

6. Apisarnthanarak A, Zack JE, Mayfield JL, Freeman J, Dunne WM, Little JR et al. Effectiveness of environmental and infection control programs to reduce transmission of Clostridium difficile. Clin Infect Dis 2004;39(4):601-602. [PubMed] 

7. Arabi Y, Dimock F, Burdon DW, exander-Williams J, Keighley MR. Influence of neomycin and metronidazole on colonic microflora of volunteers. J Antimicrob Chemother 1979 ;5(5):531-537. [PubMed]

8. Bacon AE, McGrath S, Fekety R, Holloway WJ. In vitro synergy studies with Clostridium difficile. Antimicrob Agents Chemother 1991;35(3):582-583. [PubMed

9. Bannatyne R, Jackowski J. Susceptibility of Clostridium difficile to metronidazole, its bioactive metabolites and tinidazole. Eur J Clin Microbiol 1987;6(4):505-506.  [PubMed]

10. Barbut F, Decre D, Burghoffer B, Lesage D, Delisle F, Lalande V et al. Antimicrobial susceptibilities and serogroups of clinical strains of Clostridium difficile isolated in France in 1991 and 1997. Antimicrob Agents Chemother 1999;43(11):2607-2611. [PubMed]

11. Barbut F, Decre D, Lalande V, Burghoffer B, Noussair L, Gigandon A et al. Clinical features of Clostridium difficile-associated diarrhoea due to binary toxin (actin-specific ADP-ribosyltransferase)-producing strains. J Med Microbiol 2005;54(Pt 2):181-185. [PubMed]

12.  Bartlett JG. Treatment of antibiotic-associated pseudomembranous colitis. Rev Infect Dis 1984;6 Suppl 1:S235-S241. [PubMed]

13. Bartlett JG. New drugs for Clostridium difficile infection. Clin Infect Dis 2006;43(4):428-431.[PubMed]   

14.  Beard CM, Noller KL, O'Fallon WM, Kurland LT, Dahlin DC. Cancer after exposure to metronidazole. Mayo Clin Proc 1988;63(2):147-153. [PubMed]

15. Beckly J, Lewis S. Probiotics and antibiotic associated diarrhoea. The case for probiotics remains unproved 1. BMJ 2002;325(7369):901. [PubMed]

16. Biavasco F, Manso E, Varaldo PE. In vitro activities of ramoplanin and four glycopeptide antibiotics against clinical isolates of Clostridium difficile. Antimicrob Agents Chemother 1991;35(1):195-197. [PubMed]  

17.  Boero M, Berti E, Morgando A, Verme G. Treatment of pseudomembranous colitis: a randomized controlled trial with rifaximine vs vancomycin. Microbiologia Medica 1990;5:74-77. [PubMed]

18. Bolton RP, Culshaw MA. Faecal metronidazole concentrations during oral and intravenous therapy for antibiotic associated colitis due to Clostridium difficile. Gut 1986;27(10):1169-1172.  [PubMed]

19.  Borody TJ. "Flora Power"-- fecal bacteria cure chronic C. difficile diarrhea. Am J Gastroenterol 2000 November;95(11):3028-3029. [PubMed]

20. Bowden TA, Jr., Mansberger AR, Jr., Lykins LE. Pseudomembraneous enterocolitis: mechanism for restoring floral homeostasis. Am Surg 1981;47(4):178-183. [PubMed]

21. Brazier JS, Fawley W, Freeman J, Wilcox MH. Reduced susceptibility of Clostridium difficile to metronidazole. J Antimicrob Chemother 2001;48(5):741-742. [PubMed]

22.  Brooks SE, Veal RO, Kramer M, Dore L, Schupf N, Adachi M. Reduction in the incidence of Clostridium difficile-associated diarrhea in an acute care hospital and a skilled nursing facility following replacement of electronic thermometers with single-use disposables. Infect Control Hosp Epidemiol 1992;13(2):98-103. [PubMed]

23. Buggy BP, Fekety R, Silva J, Jr. Therapy of relapsing Clostridium difficile-associated diarrhea and colitis with the combination of vancomycin and rifampin. J Clin Gastroenterol 1987;9(2):155-159. [PubMed]

24. Burdon DW, Brown JD, Youngs DJ, Arabi Y, Shinagawa N, exander-Williams J et al. Antibiotic susceptibility of Clostridium difficile. J Antimicrob Chemother 1979;5(3):307-310. [PubMed]

25. Cassone M, Serra P, Mondello F, Girolamo A, Scafetti S, Pistella E et al. Outbreak of Saccharomyces cerevisiae subtype boulardii fungemia in patients neighboring those treated with a probiotic preparation of the organism. J Clin Microbiol 2003;41(11):5340-5343. [PubMed]

26. Clabots CR, Johnson S, Olson MM, Peterson LR, Gerding DN. Acquisition of Clostridium difficile by hospitalized patients: evidence for colonized new admissions as a source of infection. J Infect Dis 1992 September;166(3):561-567.[PubMed]

27. Clabots CR, Shanholtzer CJ, Peterson LR, Gerding DN. In vitro activity of efrotomycin, ciprofloxacin, and six other antimicrobials against Clostridium difficile. Diagn Microbiol Infect Dis 1987;6(1):49-52. [PubMed]

28. Climo MW, Israel DS, Wong ES, Williams D, Coudron P, Markowitz SM. Hospital-wide restriction of clindamycin: effect on the incidence of Clostridium difficile-associated diarrhea and cost. Ann Intern Med 1998;128(12 Pt 1):989-995. [PubMed].

29. Cone JB, Wetzel W. Toxic megacolon secondary to pseudomembranous colitis. Dis Colon Rectum 1982;25(5):478-482. [PubMed]

30. Cronberg S, Castor B, Thoren A. Fusidic acid for the treatment of antibiotic-associated colitis induced by Clostridium difficile. Infection 1984;12(4):276-279. [PubMed]

31. Cunningham R, Dale B, Undy B, Gaunt N. Proton pump inhibitors as a risk factor for Clostridium difficile diarrhoea. J Hosp Infect 2003 July;54(3):243-245. [PubMed]

32. D'Souza AL, Rajkumar C, Cooke J, Bulpitt CJ. Probiotics in prevention of antibiotic associated diarrhoea: meta-analysis. BMJ 2002;324(7350):1361. [PubMed]

33. Dallal RM, Harbrecht BG, Boujoukas AJ, Sirio CA, Farkas LM, Lee KK et al. Fulminant Clostridium difficile: an underappreciated and increasing cause of death and complications. Ann Surg 2002;235(3):363-372. [PubMed]

34. Davey P, Brown E, Fenelon L, Finch R, Gould I, Hartman G et al. Interventions to improve antibiotic prescribing practices for hospital inpatients. Cochrane Database Syst Rev 2005;(4):CD003543. [PubMed]

35. de Lalla LF, Nicolin R, Rinaldi E, Scarpellini P, Rigoli R, Manfrin V et al. Prospective study of oral teicoplanin versus oral vancomycin for therapy of pseudomembranous colitis and Clostridium difficile-associated diarrhea. Antimicrob Agents Chemother 1992;36(10):2192-2196. [PubMed]  

36. Dellit TH, Owens RC, McGowan JE Jr, Gerding DN, Weinstein RA, Burke JP et al. Infectious diseases society of america and the society for healthcare epidemiology of america guidelines for developing an institutional program to enhance antimicrobial stewardship. Clin Infect Dis 2007;44(2):159-177. [PubMed]

37. Dendukuri N, Costa V, McGregor M, Brophy JM. Probiotic therapy for the prevention and treatment of Clostridium difficile-associated diarrhea: a systematic review. CMAJ 2005;173(2):167-170. [PubMed]

38. Dial S, Alrasadi K, Manoukian C, Huang A, Menzies D. Risk of Clostridium difficile diarrhea among hospital inpatients prescribed proton pump inhibitors: cohort and case-control studies. CMAJ 2004;171(1):33-38. [PubMed]

39. Dial S, Delaney JA, Barkun AN, Suissa S. Use of gastric acid-suppressive agents and the risk of community-acquired Clostridium difficile-associated disease. JAMA 2005;294(23):2989-2995. [PubMed]

40. Dudley MN, McLaughlin JC, Carrington G, Frick J, Nightingale CH, Quintiliani R. Oral bacitracin vs vancomycin therapy for Clostridium difficile-induced diarrhea. A randomized double-blind trial. Arch Intern Med 1986;146(6):1101-4. [PubMed]

41.  Dzink J, Bartlett JG. In vitro susceptibility of Clostridium difficile isolates from patients with antibiotic-associated diarrhea or colitis. Antimicrob Agents Chemother 1980;17(4):695-698. [PubMed]

42. Enache-Angoulvant A, Hennequin C. Invasive Saccharomyces infection: a comprehensive review. Clin Infect Dis 2005;41(11):1559-1568. [PubMed] 

43. Ensminger PW, Counter FT, Thomas LJ, Lubbehusen PP. Susceptibility, resistance development, and synergy of antimicrobial combinations against Clostridium difficile. Curr Microbiol 1982;7:59-62. [PubMed]

44. Fekety R. Guidelines for the diagnosis and management of Clostridium difficile-associated diarrhea and colitis. American College of Gastroenterology, Practice Parameters Committee. Am J Gastroenterol 1997;92(5):739-750.[PubMed]

45. Fekety R, Shah AB. Diagnosis and treatment of Clostridium difficile colitis. JAMA 1993 January 6;269(1):71-75. [PubMed]

46. Fekety R, Silva J, Kauffman C, Buggy B, Deery HG. Treatment of antibiotic-associated Clostridium difficile colitis with oral vancomycin: comparison of two dosage regimens. Am J Med 1989;86(1):15-19. [PubMed]

47. Fekety R, Silva J, Toshniwal R, Allo M, Armstrong J, Browne R et al. Antibiotic-associated colitis: effects of antibiotics on Clostridium difficile and the disease in hamsters. Rev Infect Dis 1979;1(2):386-397. [PubMed]

48.  Freeman J, Baines SD, Jabes D, Wilcox MH. Comparison of the efficacy of ramoplanin and vancomycin in both in vitro and in vivo models of clindamycin-induced Clostridium difficile infection. J Antimicrob Chemother 2005;56(4):717-725. [PubMed]

49. Friedenberg F, Fernandez A, Kaul V, Niami P, Levine GM. Intravenous metronidazole for the treatment of Clostridium difficile colitis. Dis Colon Rectum 2001;44(8):1176-1180.[PubMed] 

50. George WL, Rolfe RD, Finegold SM. Treatment and prevention of antimicrobial agent-induced colitis and diarrhae. Gastroenterology 1980 August;79(2):366-372. [PubMed]

51. George WL, Volpicelli NA, Stiner DB, Richman DD, Liechty EJ, Mok HY et al. Relapse of pseudomembranous colitis after vancomycin therapy. N Engl J Med 1979;301(8):414-415. [PubMed]

52. Gerding DN, Johnson S, Osmolski JR, Sambol SP. In vitro activity of ramoplanin, rifalazil, rifaximin, metronidazole, and vancomycin against 110 unique toxigenic Clostridium difficile clinical isolates. [Abstract E-1439]. In: Program and abstracts of the 45th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington, DC, December 16-19, 2005.Washington, DC: American Society for Microbiology, 2005,171. [PubMed]

53. Gerding DN, Johnson S, Peterson LR, Mulligan ME, Silva J, Jr. Clostridium difficile-associated diarrhea and colitis. Infect Control Hosp Epidemiol 1995;16(8):459-477. [PubMed]

54. Gerding DN, Olson MM, Johnson S, Peterson LR, Lee JT, Jr. Clostridium difficile diarrhea and colonization after treatment with abdominal infection regimens containing clindamycin or metronidazole. Am J Surg 1990;159(2):212-217. [PubMed]

55. Geric B, Carman RJ, Rupnik M, Genheimer CW, Sambol SP, Lyerly DM et al. Binary toxin-producing, large clostridial toxin-negative Clostridium difficile strains are enterotoxic but do not cause disease in hamsters 1. J Infect Dis 2006;193(8):1143-1150. [PubMed]

56. Goodpasture HC, Dolan PJ, Jr., Jacobs ER, Meredith WT. Pseudomembranous colitis & antibiotics. Kans Med 1986;87(5):133, 146. [PubMed]

57. Gorschluter M, Glasmacher A, Hahn C, Schakowski F, Ziske C, Molitor E et al. Clostridium difficile infection in patients with neutropenia. Clin Infect Dis 2001 September 15;33(6):786-791. [PubMed]

58. Guzman R, Kirkpatrick J, Forward K, Lim F. Failure of parenteral metronidazole in the treatment of pseudomembranous colitis. J Infect Dis 1988;158(5):1146-1147. [PubMed]

59. Hassett J, Meyers S, McFarland L, Mulligan ME. Recurrent Clostridium difficile infection in a patient with selective IgG1 deficiency treated with intravenous immune globulin and Saccharomyces boulardii. Clin Infect Dis 1995 June;20 Suppl 2:S266-S268. [PubMed]

60. Hoverstad T, Carlstedt-Duke B, Lingaas E, Midtvedt T, Norin KE, Saxerholt H et al. Influence of ampicillin, clindamycin, and metronidazole on faecal excretion of short-chain fatty acids in healthy subjects. Scand J Gastroenterol 1986 June;21(5):621-626. [PubMed]

61. Jang SS, Hansen LM, Breher JE, Riley DA, Magdesian KG, Madigan JE et al. Antimicrobial susceptibilities of equine isolates of Clostridium difficile and molecular characterization of metronidazole-resistant strains. Clin Infect Dis 1997 September;25 Suppl 2:S266-S267. [PubMed]

62. Johnson S, Adelmann A, Clabots CR, Peterson LR, Gerding DN. Recurrences of Clostridium difficile diarrhea not caused by the original infecting organism. J Infect Dis 1989;159(2):340-343. [PubMed]

63. Johnson S, Gerding DN. Clostridium difficile--associated diarrhea. Clin Infect Dis 1998 May;26(5):1027-1034. [PubMed]

64. Johnson S, Gerding DN, Olson MM, Weiler MD, Hughes RA, Clabots CR et al. Prospective, controlled study of vinyl glove use to interrupt Clostridium difficile nosocomial transmission. Am J Med 1990;88(2):137-140. [PubMed]

65. Johnson S, Homann SR, Bettin KM, Quick JN, Clabots CR, Peterson LR et al. Treatment of asymptomatic Clostridium difficile carriers (fecal excretors) with vancomycin or metronidazole. A randomized, placebo-controlled trial. Ann Intern Med 1992;117(4):297-302. PubMed]

66. Johnson S, Kent SA, O'Leary KJ, Merrigan MM, Sambol SP, Peterson LR et al. Fatal pseudomembranous colitis associated with a variant clostridium difficile strain not detected by toxin A immunoassay. Ann Intern Med 2001;135(6):434-438. [PubMed]

67. Johnson S, Samore MH, Farrow KA, Killgore GE, Tenover FC, Lyras D et al. Epidemics of diarrhea caused by a clindamycin-resistant strain of Clostridium difficile in four hospitals. N Engl J Med 1999;341(22):1645-1651.  [PubMed]

68. Jokipii AM, Jokipii L. Comparative activity of metronidazole and tinidazole against Clostridium difficile and Peptostreptococcus anaerobius. Antimicrob Agents Chemother 1987;31(2):183-186.  [PubMed]

69. Kazakova SV, Ware K, Baughman B, Bilukha O, Paradis A, Sears S et al. A Hospital Outbreak of Diarrhea Due to an Emerging Epidemic Strain of Clostridium difficile. Arch Intern Med 2006;166(22):2518-2524. [PubMed]

70. Kleinfeld DI, Sharpe RJ, Donta ST. Parenteral therapy for antibiotic-associated pseudomembranous colitis. J Infect Dis 1988;157(2):389. [PubMed]

71. Kunimoto D, Thomson AB. Recurrent Clostridium difficile-associated colitis responding to cholestyramine. Digestion 1986;33(4):225-228. [PubMed]

72. Kurtz CB, Cannon EP, Brezzani A, Pitruzzello M, Dinardo C, Rinard E, et al. GT160-246, a toxin binding polymer for treatment of Clostridium difficile colitis. Antimicrob Agents Chemother 2001 August;45(8):2340-2347.[PubMed]  

73. Kutty P, Benoit S, Woods C, Sena A, Naggie S, Frederick J et al. Emerging Clostridium difficile-associated disease in the community and the role of non-antimicrobial risk factors. [Abstr. LB-28]. In: Program and abstracts of the 44th Annual Infectious Diseases Society of America, Toronto, Ontario, CA. 242. [PubMed]

74. Kyne L, Warny M, Qamar A, Kelly CP. Asymptomatic carriage of Clostridium difficile and serum levels of IgG antibody against toxin A. N Engl J Med 2000;342(6):390-397. [PubMed]

75. Lagrotteria D, Holmes S, Smieja M, Smaill F, Lee C. Prospective, randomized inpatient study of oral metronidazole versus oral metronidazole and rifampin for treatment of primary episode of Clostridium difficile-associated diarrhea. Clin Infect Dis 2006;43(5):547-552. [PubMed]

76. Leischner J, Johnson S, Sambol S, Parada J, Gerding DN. Effect of alcohol hand gels and chlorhexidine hand wash in removing spores of Clostridium difficile from hands.[Abstract KB-29] In: Program and Abstracts of the 45th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy.Washington, D.C. December 2005. Interscience Conference on Antimicrobial Agents and Chemotherapy, 45th Annual Meeting. [PubMed]

77. Leung DY, Kelly CP, Boguniewicz M, Pothoulakis C, LaMont JT, Flores A. Treatment with intravenously administered gamma globulin of chronic relapsing colitis induced by Clostridium difficile toxin. J Pediatr 1991;118:633-637.[PubMed]

78. Levett PN. Time-dependent killing of Clostridium difficile by metronidazole and vancomycin. J Antimicrob Chemother 1991;27:55-62. [PubMed]

79. Lherm T, Monet C, Nougiere B, Soulier M, Larbi D, Le GC et al. Seven cases of fungemia with Saccharomyces boulardii in critically ill patients. Intensive Care Med 2002;28:797-801. [PubMed]

80. Liacouras CA, Piccoli DA. Whole-bowel irrigation as an adjunct to the treatment of chronic, relapsing Clostridium difficile colitis. J Clin Gastroenterol 1996;22:186-189. [PubMed]

81. Loo VG, Poirier L, Miller MA, Oughton M, Libman MD, Michaud S et al. A predominantly clonal multi-institutional outbreak of Clostridium difficile-associated diarrhea with high morbidity and mortality. N Engl J Med 2005;353:2442-2449. [PubMed] 

82. Louie TJ. Treatment of first recurrences of Clostridium difficile-associated disease: waiting for new treatment options. Clin Infect Dis 2006;42:765-767. [PubMed]

83. Louie TJ, Peppe J, Watt CK, Johnson D, Mohammed R, Dow G et al. Tolevamer, a novel nonantibiotic polymer, compared with vancomycin in the treatment of mild to moderately severe Clostridium difficile-associated diarrhea. Clin Infect Dis 2006;43:411-420. [PubMed]

84. Lowe DO, Mamdani MM, Kopp A, Low DE, Juurlink DN. Proton pump inhibitors and hospitalization for Clostridium difficile-associated disease: a population-based study. Clin Infect Dis 2006;43:1272-1276. [PubMed]

85. Manabe YC, Vinetz JM, Moore RD, Merz C, Charache P, Bartlett JG. Clostridium difficile colitis: an efficient clinical approach to diagnosis. Ann Intern Med 1995;123:835-840. [PubMed]

86.  Mayfield JL, Leet T, Miller J, Mundy LM. Environmental control to reduce transmission of Clostridium difficile. Clin Infect Dis 2000;31:995-1000. [PubMed]

87.  McDonald LC, Killgore GE, Thompson A, Owens RC, Jr., Kazakova SV, Sambol SP et al. An epidemic, toxin gene-variant strain of Clostridium difficile. N Engl J Med 2005;353:2433-2441.  [PubMed] 

88. McEllistrem MC, Carman RJ, Gerding DN, Genheimer CW, Zheng L. A hospital outbreak of Clostridium difficile disease associated with isolates carrying binary toxin genes. Clin Infect Dis 2005 January 15;40(2):265-272.

89. McFarland LV, Elmer GW, Surawicz CM. Breaking the cycle: treatment strategies for 163 cases of recurrent Clostridium difficile disease. Am J Gastroenterol 2002;97:1769-1775. [PubMed]

90. McFarland LV, Mulligan ME, Kwok RY, Stamm WE. Nosocomial acquisition of Clostridium difficile infection. N Engl J Med 1989;320:204-210. [PubMed]

91. McFarland LV, Surawicz CM, Greenberg RN, Fekety R, Elmer GW, Moyer KA et al. A randomized placebo-controlled trial of Saccharomyces boulardii in combination with standard antibiotics for Clostridium difficile disease. JAMA 1994;271:1913-1918. [PubMed]

92. McPherson S, Rees CJ, Ellis R, Soo S, Panter SJ. Intravenous immunoglobulin for the treatment of severe, refractory, and recurrent Clostridium difficile diarrhea. Dis Colon Rectum 2006;49:640-645. [PubMed]  

93. Mogg GA, Arabi Y, Youngs D, Johnson M, Bentley S, Burdon DW et al. Therapeutic trials of antibiotic associated colitis. Scand J Infect Dis Suppl 1980;:41-45. [PubMed]

94. Mogg GA, George RH, Youngs D, Johnson M, Thompson H, Burdon DW et al. Randomized controlled trial of colestipol in antibiotic-associated colitis. Br J Surg 1982;69:137-139. [PubMed]

95. Moncino MD, Falletta JM. Multiple relapses of Clostridium difficile-associated diarrhea in a cancer patient. Successful control with long-term cholestyramine therapy. Am J Pediatr Hematol Oncol 1992;14:361-364. [PubMed]

96. Morris JB, Zollinger RM, Jr., Stellato TA. Role of surgery in antibiotic-induced pseudomembranous enterocolitis. Am J Surg 1990;160:535-539. [PubMed]

97. Musher DM, Logan N, Hamill RJ, Dupont HL, Lentnek A, Gupta A et al. Nitazoxanide for the treatment of Clostridium difficile colitis. Clin Infect Dis 2006;43:421-427. [PubMed]

98. Muto CA, Pokrywka M, Shutt K, Mendelsohn AB, Nouri K, Posey K et al. A large outbreak of Clostridium difficile-associated disease with an unexpected proportion of deaths and colectomies at a teaching hospital following increased fluoroquinolone use. Infect Control Hosp Epidemiol 2005;26:273-280. [PubMed]

99. Nakai A, Nishikata M, Matsuyama K, Ichikawa M. Drug interaction between simvastatin and cholestyramine in vitro and in vivo. Biol Pharm Bull 1996;19:1231-1233. [PubMed]

100. Novak E, Lee JG, Seckman CE, Phillips JP, DiSanto AR. Unfavorable effect of atropine-diphenoxylate (Lomotil) therapy in lincomycin-caused diarrhea. JAMA 1976;235:1451-1454. [PubMed]

101. Olson MM, Shanholtzer CJ, Lee JT, Jr., Gerding DN. Ten years of prospective Clostridium difficile-associated disease surveillance and treatment at the Minneapolis VA Medical Center, 1982-1991. Infect Control Hosp Epidemiol 1994;15:371-381. [PubMed]

102. Owens RC. Clostridium difficile-associated disease: an emerging threat to patient safety: insights from the Society of Infectious Diseases Pharmacists. Pharmacotherapy 2006;26:299-311. [PubMed]

103.  Pantosti A, Luzzi I, Cardines R, Gianfrilli P. Comparison of the in vitro activities of teicoplanin and vancomycin against Clostridium difficile and their interactions with cholestyramine. Antimicrob Agents Chemother 1985;28:847-848.[PubMed]

104. Pasic M, Jost R, Carrel T, Von SL, Turina M. Intracolonic vancomycin for pseudomembranous colitis. N Engl J Med 1993;329:583. [PubMed]

105. Pear SM, Williamson TH, Bettin KM, Gerding DN, Galgiani JN. Decrease in nosocomial Clostridium difficile-associated diarrhea by restricting clindamycin use. Ann Intern Med 1994;120:272-277. [PubMed]

106. Pepin J, Alary ME, Valiquette L, Raiche E, Ruel J, Fulop K et al. Increasing risk of relapse after treatment of Clostridium difficile colitis in Quebec, Canada. Clin Infect Dis 2005;40:1591-1597. [PubMed]

107. Pepin J, Routhier S, Gagnon S, Brazeau I. Management and outcomes of a first recurrence of Clostridium difficile-associated disease in Quebec, Canada. Clin Infect Dis 2006;42:758-764. [PubMed]

108. Pepin J, Saheb N, Coulombe MA, Alary ME, Corriveau MP, Authier S, et al. Emergence of fluoroquinolones as the predominant risk factor for Clostridium difficile-associated diarrhea: a cohort study during an epidemic in Quebec. Clin Infect Dis 2005;41:1254-1260. [PubMed]

109. Pepin J, Valiquette L, Cossette B. Mortality attributable to nosocomial Clostridium difficile-associated disease during an epidemic caused by a hypervirulent strain in Quebec. CMAJ 2005;173:1037-1042.  [PubMed] 

110. Persky SE, Brandt LJ. Treatment of recurrent Clostridium difficile-associated diarrhea by administration of donated stool directly through a colonoscope. Am J Gastroenterol 2000;95:3283-3285. [PubMed]

111. Pruksananonda P, Powell KR. Multiple relapses of Clostridium difficile-associated diarrhea responding to an extended course of cholestyramine. Pediatr Infect Dis J 1989;8:175-178. [PubMed]

112. Rammer M, Kirchgatterer A, Hobling W, Knoflach P. Lansoprazole-associated collagenous colitis: a case report. Z Gastroenterol 2005;43:657-660. [PubMed]

113. Rolfe RD, Iaconis JP. Intestinal colonization of infant hamsters with Clostridium difficile. Infect Immun 1983;42:480-486.  [PubMed]

114. Salminen MK, Rautelin H, Tynkkynen S, Poussa T, Saxelin M, Valtonen V et al. Lactobacillus bacteremia, clinical significance, and patient outcome, with special focus on probiotic L. rhamnosus GG. Clin Infect Dis 2004;38:62-69. [PubMed]

115. Sambol SP, Merrigan MM, Tang JK, Johnson S, Gerding DN. Colonization for the prevention of Clostridium difficile disease in hamsters. J Infect Dis 2002;186:1781-1789. [PubMed]

116. Samore MH, DeGirolami PC, Tlucko A, Lichtenberg DA, Melvin ZA, Karchmer AW. Clostridium difficile colonization and diarrhea at a tertiary care hospital. Clin Infect Dis 1994;18:181-187.  [PubMed]

117. Sanchez JL, Gerding DN, Olson MM, Johnson S. Metronidazole susceptibility in Clostridium difficile isolates recovered from cases of C. difficile-associated disease treatment failures and successes. Anaerobe 1999;5:205-208.[PubMed]

118. Schwan A, Sjolin S, Trottestam U, Aronsson B. Relapsing Clostridium difficile enterocolitis cured by rectal infusion of normal faeces. Scand J Infect Dis 1984;16:211-215. [PubMed]

119.  Seal D, Borriello SP, Barclay F, Welch A, Piper M, Bonnycastle M. Treatment of relapsing Clostridium difficile diarrhoea by administration of a non-toxigenic strain. Eur J Clin Microbiol 1987;6:51-53. [PubMed]

120.  Settle CD, Wilcox MH, Fawley WN, Corrado OJ, Hawkey PM. Prospective study of the risk of Clostridium difficile diarrhoea in elderly patients following treatment with cefotaxime or piperacillin-tazobactam. Aliment Pharmacol Ther 1998;12:1217-`1223. [PubMed]

121. Shetler K, Nieuwenhuis R, Wren SM, Triadafilopoulos G. Decompressive colonoscopy with intracolonic vancomycin administration for the treatment of severe pseudomembranous colitis. Surg Endosc 2001;15:653-659. [PubMed]

122. Silva J, Jr. Update on pseudomembranous colitis. West J Med 1989;151:644-648. [PubMed]

123. Sougioultzis S, Kyne L, Drudy D, Keates S, Maroo S, Pothoulakis C et al. Clostridium difficile toxoid vaccine in recurrent C. difficile-associated diarrhea. Gastroenterology 2005;128:764-770.  [PubMed]

124. Surawicz CM, McFarland LV, Elmer G, Chinn J. Treatment of recurrent Clostridium difficile colitis with vancomycin and Saccharomyces boulardii. Am J Gastroenterol 1989;84:1285-1287. [PubMed]

125. Surawicz CM, McFarland LV, Greenberg RN, Rubin M, Fekety R, Mulligan ME et al. The search for a better treatment for recurrent Clostridium difficile disease: use of high-dose vancomycin combined with Saccharomyces boulardii. Clin Infect Dis 2000;31:1012-1017. [PubMed]

126. Swanson RN, Hardy DJ, Shipkowitz NL, Hanson CW, Ramer NC, Fernandes PB et al. In vitro and in vivo evaluation of tiacumicins B and C against Clostridium difficile. Antimicrob Agents Chemother 1991;35:1108-1111. [PubMed]

127. Taylor NS, Bartlett JG. Binding of Clostridium difficile cytotoxin and vancomycin by anion-exchange resins. J Infect Dis 1980;141:92-97.  [PubMed]

128. Teasley DG, Gerding DN, Olson MM, Peterson LR, Gebhard RL, Schwartz MJ et al. Prospective randomised trial of metronidazole versus vancomycin for Clostridium-difficile-associated diarrhoea and colitis. Lancet 1983;2:1043-1046. [PubMed]

129. Tedesco FJ. Treatment of recurrent antibiotic-associated pseudomembranous colitis. Am J Gastroenterol 1982;77:220-221. [PubMed]

130. Tedesco FJ, Gordon D, Fortson WC. Approach to patients with multiple relapses of antibiotic-associated pseudomembranous colitis. Am J Gastroenterol 1985;80:867-868. [PubMed]

131. Thomson RD, Lestina LS, Bensen SP, Toor A, Maheshwari Y, Ratcliffe NR. Lansoprazole-associated microscopic colitis: a case series. Am J Gastroenterol 2002;97:2908-2913. [PubMed]

132.  Thorpe CM, Gorbach SL. Update on Clostridium difficile. Curr Treat Options Gastroenterol 2006;9:265-271. [PubMed]

133. Tvede M, Rask-Madsen J. Bacteriotherapy for chronic relapsing Clostridium difficile diarrhoea in six patients. Lancet 1989;1:1156-1160. [PubMed]

134. von Eichel-Streiber C, Boquet P, Sauerborn M, Thelestam M. Large clostridial cytotoxins--a family of glycosyltransferases modifying small GTP-binding proteins. Trends Microbiol 1996;4:375-382. [PubMed]

135.  Walley T, Milson D. Loperamide related toxic megacolon in Clostridium difficile colitis. Postgrad Med J 1990;66:582. [PubMed]

136. Walters BA, Roberts R, Stafford R, Seneviratne E. Relapse of antibiotic associated colitis: endogenous persistence of Clostridium difficile during vancomycin therapy. Gut 1983;24:206-212. [PubMed]

137. Warny M, Denie C, Delmee M, Lefebvre C. Gamma globulin administration in relapsing Clostridium difficile-induced pseudomembranous colitis with a defective antibody response to toxin A. Acta Clin Belg 1995;50:36-39. [PubMed]

138. Warny M, Pepin J, Fang A, Killgore G, Thompson A, Brazier J et al. Toxin production by an emerging strain of Clostridium difficile associated with outbreaks of severe disease in North America and Europe. Lancet 2005;366:1079-1084. [PubMed]

139. Wenisch C, Parschalk B, Hasenhundl M, Hirschl AM, Graninger W. Comparison of vancomycin, teicoplanin, metronidazole, and fusidic acid for the treatment of Clostridium difficile-associated diarrhea. Clin Infect Dis 1996;22:813-818.  [PubMed]

140. Wilcox MH. Descriptive study of intravenous immunoglobulin for the treatment of recurrent Clostridium difficile diarrhoea. J Antimicrob Chemother 2004;53:882-884. [PubMed]

141. Wilcox MH, Howe R. Diarrhoea caused by Clostridium difficile: response time for treatment with metronidazole and vancomycin. J Antimicrob Chemother 1995;36:673-679. [PubMed]

142. Wilson KH. The microecology of Clostridium difficile. Clin Infect Dis 1993;16 Suppl 4:S214-S218.[PubMed]

143. Wong SS, Woo PC, Luk WK, Yuen KY. Susceptibility testing of Clostridium difficile against metronidazole and vancomycin by disk diffusion and Etest. Diagn Microbiol Infect Dis 1999;34:1-6. [PubMed]

144. Young GP, Ward PB, Bayley N, Gordon D, Higgins G, Trapani JA, et al. Antibiotic-associated colitis due to Clostridium difficile: double-blind comparison of vancomycin with bacitracin. Gastroenterology 1985;89:1038-1045.[PubMed]