oa Molecular Diagnosis and Vaccines - Comparative evaluation of mecA gene detection with phenotypic conventional testing for methicillin resistant Staphylococcus aureus
Early detection of methicillin resistant Staph. aureus (MRSA) is critical for both the management of infected patients and the timely institation of appropriate infection control measures. To compare conventional phenotypic methods for detection of MRSA in routine laboratory practice with the wellestablished molecular method, mecA gene detection, this study was conducted on 50 patients with pyogenic infections. Samples were cultured on selective media and isolated Staph. aureus was identified using standard methods. MRSA isolates were identified using disc diffusion, salt agar screen test and BBL crystal MRSA ID system. Polymerase Chain Reaction (PCR) with primers specific for mecA gene was done for all isolates. MRSA was identified in 33.3% of the isolates by mecA-PCR as compared to 25%, 27.8% and 27.8 by the disc diffusion and agar screen and BBL crystal methods respectively. When mecA was used as gold standard the sensitivity was 75%, 83.3% and 83.3% for the disc diffusion, salt agar screen and BBL crystal method respectively and the specificity was 100% for all. It is concluded that although mecA-PCR is a reliable method for diagnosis of methicillin resistance Staph. aureus, the rapid and cheap conventional tests offer an acceptable alternative for smaller, non reference laboratories and reduce the dependency on PCR in larger laboratories for routine confirmation.
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