Comparison of phenotypic methods and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry for the identification of aero-tolerant Actinomyces spp. isolated from soft-tissue infections

Eur J Clin Microbiol Infect Dis. 2012 Aug;31(8):1749-52. doi: 10.1007/s10096-011-1496-3. Epub 2011 Dec 6.

Abstract

Aero-tolerant Actinomyces spp. are an under-recognised cause of cutaneous infections, in part because identification using conventional phenotypic methods is difficult and may be inaccurate. Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) is a promising new technique for bacterial identification, but with limited data on the identification of aero-tolerant Actinomyces spp. This study evaluated the accuracy of a phenotypic biochemical kit, MALDI-TOF MS and genotypic identification methods for the identification of this problematic group of organisms. Thirty aero-tolerant Actinomyces spp. were isolated from soft-tissue infections over a 2-year period. Species identification was performed by 16 s rRNA sequencing and genotypic results were compared with results obtained by API Coryne and MALDI-TOF MS. There was poor agreement between API Coryne and genotypic identification, with only 33% of isolates correctly identified to the species level. MALDI-TOF MS correctly identified 97% of isolates to the species level, with 33% of identifications achieved with high confidence scores. MALDI-TOF MS is a promising new tool for the identification of aero-tolerant Actinomyces spp., but improvement of the database is required in order to increase the confidence level of identification.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinomyces / chemistry
  • Actinomyces / classification*
  • Actinomyces / isolation & purification*
  • Actinomyces / physiology
  • Actinomycosis / diagnosis*
  • Actinomycosis / microbiology
  • Bacterial Typing Techniques
  • Bacteriological Techniques / methods*
  • Genes, rRNA / genetics
  • Humans
  • Molecular Typing
  • RNA, Ribosomal, 16S / genetics
  • Sensitivity and Specificity
  • Soft Tissue Infections / diagnosis*
  • Soft Tissue Infections / microbiology
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*

Substances

  • RNA, Ribosomal, 16S