An inexpensive and reliable method for routine identification of staphylococcal species

Eur J Clin Microbiol Infect Dis. 1998 May;17(5):327-35. doi: 10.1007/BF01709455.

Abstract

The aim of this study was to develop a simple, reliable, and inexpensive in-house system for routine species identification of staphylococci in clinical practice. The system combines 15 key tests (including carbohydrate fermentation) performed in micro-well strips and antimicrobial disk diffusion susceptibility tests performed on standardised paper disk method antibiotic sensitivity medium agar. Twenty-eight staphylococcal reference strains belonging to 18 different species were correctly identified using this in-house system. A total of 291 clinical staphylococci isolates were evaluated with the in-house system and a conventional identification scheme. The in-house system identified 281 (96.6%) of these 291 isolates. Eleven different species were recognised. The five species most frequently identified were Staphylococcus epidermidis (48.6%), Staphylococcus aureus (27.8%), Staphylococcus haemolyticus (8.2%), Staphylococcus hominis (5.7%), and Staphylococcus warneri (5.3%). There was an agreement of 86.3% between the species identification obtained with the in-house system and the conventional identification scheme. All coagulase-negative isolates initially identified as species other than Staphylococcus epidermidis as well as indistinctly identified isolates were also evaluated with a commercial identification system. The agreement between species identification obtained with the in-house system and the commercial system for 101 identified isolates was 73%. Several isolates that were difficult to distinguish with the conventional scheme and/or the commercial system were identified with the aid of the antimicrobial susceptibility test included in the in-house system. The described test scheme should be of value for identification of clinically significant staphylococci species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agar
  • Anti-Bacterial Agents / pharmacology
  • Bacterial Typing Techniques*
  • Carbohydrate Metabolism
  • Coagulase / metabolism
  • Humans
  • Microbial Sensitivity Tests / methods
  • Reagent Kits, Diagnostic
  • Reference Standards
  • Species Specificity
  • Staphylococcal Infections / microbiology*
  • Staphylococcus / classification*
  • Staphylococcus / enzymology
  • Staphylococcus / growth & development
  • Staphylococcus / isolation & purification*

Substances

  • Anti-Bacterial Agents
  • Coagulase
  • Reagent Kits, Diagnostic
  • Agar