Comparative Evaluation of Five Culture Media with Triplex PCR Assay for Detection of Methicillin-Resistant Staphylococcus aureus

• Published in: Current microbiology 2010-07, Vol.61 (1), p.1-6
• Main Authors: Al-Talib, Hassanain, Yean, Chan Yean, Al-khateeb, Alyaa, Singh, Kirnpal-Kaur Banga, Hasan, Habsah, Al-Jashamy, Karim, Ravichandran, Manickam
• Format: Article
• Language: English
• Subjects: Agar; Anti-Bacterial Agents - pharmacology; Biomedical and Life Sciences; Biotechnology; Cefoxitin - pharmacology; Cell culture; Comparative studies; Culture Media; Drug resistance; Humans; Life Sciences; 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; Microbiology; Nosocomial infection; Oxacillin - pharmacology; Polymerase chain reaction; 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; Staphylococcus infections
• ISSN: 0343-8651; 1432-0991
• DOI: 10.1007/s00284-009-9567-8

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 μg/ml (MSC-4) and 6 μg/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.