Table 1.  In Vitro Susceptibilities Cardiobacterium hominisa

 

 

Antimicrobial agent

 

n

Representative MIC (µg/ml)b

 

 

Breakpointc

 

n (%) susceptible

 

Penicillin

22

0.05

 

22 (100%)

 

Ampicillin

16

<0.4

 

15 (94%)

 

Oxacillin

3

NAd

 

2 (67%)

 

Carbenicillin

5

<1.6

£16

4(100%)

 

Cephalothin

11

<0.4

£8

11 (100%)

 

Chloramphenicol

17

1.25

£8

17 (100%)

 

Colistin

2

NA

 

2 (100%)

 

Trimethoprim-sulphamethoxazole

 

3

NA

£2/38

2 (100%)

 

Sulfonamide

1

NA

 

0 (0%)

 

Tetracycline

19

0.25

£4

19 (100%)

 

Erythromycin

14

NA

£0.5

11 (79%)

 

Gentamicin

9

<0.8

£4

8 (89%)

 

Kanamycin

6

<0.8

£16

1 (17%)

 

Streptomycin

14

1.6

 

14 (100%)

 

Tobramycin

2

NA

£4

2 (100%)

 

Rifampin

1

NA

£1

1 (100%)

 

Vancomycin

3

25

£4

1 (33%)

 

Clindamycin

2

5

£0.5

0 (0%)

 

a  Modified from Wormser GP, Bottone EJ. Cardiobacterium hominis: review of microbiological and clinical features. Rev Infect Dis 1983; 5:680-691.

b  MIC50, MIC90 and MIC Range not reported.

c  NCCLS interpretive standards for susceptibility (µg/ml) (52).

d  NA = Data not available

 

 

 

Table 2: In Vitro Susceptibility Testing of HACEK Organismsa 

 

Susceptible (µg/ml)

Intemediate (µg/ml)

Resistant (µg/ml)

Ampicillin

<1

2

>4

Ampicillin/sulbactam

<2/1

-

>4/2

Amoxycllin/clavulanic acid

<4/1

-

>8/2

Penicillin

<1

3

>4

Ceftriaxone / Cefotaxime

<2

-

-

Imipenem/meropenem b

<0.5

1

>2

 a Clinical and Laboratory Standards  Institute. Methods for antimicrobial dilution and disk susceptibility testing of infrequently isolated or fastidious bacteria. Approved standard M45-A. Wayne, PA: Clinical and Laboratory Standards Institute 2006.

 b unless  Haemophilus spp. isolates; susceptible: 4 µg/ml, intermediate: 8 µg/ml, resistant: 16 µg/ml

 

Table 3: Therapy for Both Native and Prosthetic Valve Endocarditis Caused by HACEK Microorganismsa

 

Regimen

Dosage and route

Native valve

Duration, wk

Prosthetic valve

Duration, wk

Comments

Ceftriaxone

2g/24h IV/IM in 1 dose

4

6

Cefotaxime or another third or fourth generation cephalosporin may be substituted

or

 

 

 

 

Ampicillin-sulbactam

 

4

6

 

or

 

 

 

 

Ciprofloxacin

 

1000mg/24h PO or 800mg/24 IV in 2 equally divided doses

4

6

Only for patients unable to tolerate cephalosporin and ampicillin therapy

Levofloxacin, gatifloxacin or moxifloxacin may be substituted.

Fluoroquinolones not generally recommended for patients <18 y old.

 a Modified from Baddour L, Wilson W, Bayer A et al. Infective endocarditis: diagnosis, antimicrobial therapy, and

management of complication: a statement for healthcare professionals from the Committee on Rheumatic Fever,

Endocarditis and Kawasaki Disease, Council on Cardiovascular Disease in the Young and the Councils on Clinical

Cardiology, Stroke, and Cardiovascular Surgery and Anesthesia, American Heart Association: endorsed by the Infectious

Diseases Society of America. Circ 2005; 111: e394-434.