Comparative evaluation of five culture media with triplex PCR assay for detection of methicillin-resistant Staphylococcus aureus

Curr Microbiol. 2010 Jul;61(1):1-6. doi: 10.1007/s00284-009-9567-8. Epub 2009 Dec 24.

Abstract

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) is responsible for nosocomial and community-acquired infections. Hence, rapid and accurate laboratory diagnosis of MRSA is a vital constituent of control measures. The present study evaluated five different methods for the identification of MRSA. A total of 207 S. aureus clinical isolates that consisted of 89 MRSA and 118 methicillin-susceptible S. aureus (MSSA) strains confirmed by PCR were tested. MRSA strains were evaluated by five different methods: chromogenic MRSA agar (CMRSA), oxacillin resistance screening agar base (ORSAB), mannitol salt oxacillin agar (MSO), mannitol salt cefoxitin agar with two different concentrations of cefoxitin [4 microg/ml (MSC-4) and 6 microg/ml (MSC-6)]. The results of the different methods were compared to mecA PCR as the gold standard. MSC-6 showed only six false-positive MRSA in comparison with PCR. The sensitivities and specificities of MSC-6, MSC-4, MSO-4, ORSAB, and CMRSA were as follows: 98.9/94.9%, 100/83.1%, 89.9/87.3%, 97.8/96.6%, and 95.5/94.9%, respectively. In comparison with PCR, it was found that both MSC-6 and ORSAB were relatively the least expensive screening tests ($0.70 and $1.00, respectively). In conclusion, all methods were comparable, but MSC-6 was the least expensive medium for MRSA screening.

Publication types

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

MeSH terms

  • Agar
  • Anti-Bacterial Agents / pharmacology
  • Cefoxitin / pharmacology
  • Culture Media*
  • Humans
  • Methicillin / pharmacology
  • Methicillin Resistance
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Methicillin-Resistant Staphylococcus aureus / growth & development
  • Methicillin-Resistant Staphylococcus aureus / isolation & purification*
  • Microbial Sensitivity Tests
  • Oxacillin / pharmacology
  • Polymerase Chain Reaction / methods
  • Sensitivity and Specificity
  • Staphylococcal Infections / microbiology
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / genetics
  • Staphylococcus aureus / growth & development
  • Staphylococcus aureus / isolation & purification

Substances

  • Anti-Bacterial Agents
  • Culture Media
  • Cefoxitin
  • Agar
  • Methicillin
  • Oxacillin