RAPID DETECTION OF METHICILLIN AND VANCOMYCIN RESISTANCE IN STAPHYLOCOCCUS AUREUS BY DETECTION OF MECA, VANA, VANB GENES BY PCRR. SHARMA, B. MALHOTRA AND R.S. BEDWAL
Staphylococcus aureus are major human pathogens capable of causing a wide range of infections. Genotypic method is now being used to rapidly detect MRSA and vancomycin resistance. Objectives of the work were to study the occurrence of methicillin and vancomycin resistance in Staph by genotypic and phenotypic methods. Four hundred and fifteen isolates of Staphylococci obtained from clinical samples. MRSA were detected by culture on oxacillin salt agar with 4% NaCl and 6 μg/mL of oxacillin and VRSA with 6 μg/mL vancomycin. PCR amplification of mecA and vanA, vanB gene was done at ADRL of SMS Medical College. 107/205 (52.19%) S. aureus isolates were classified as MSSA and 98/205 (47.80%) as MRSA. All the MRSA (98) isolates were positive for mecA gene by PCR. 3 MSSA were also positive for mecA gene detected by PCR. All VISA (7) were negative for vanA and vanB gene. All 4 VRSA were negative for vanA gene but 1VRSA from pus was positive for vanB gene and 3 were negative for vanB gene. In the current study except one strain from pus was positive for vanB gene, all strains of VRSA and VISA strains were negative for vanA/vanB gene by PCR. The absence of vanA/B genes in the present isolates does not rule out that these strains are not VRSA or VISA as thickening of cell wall may also be responsible for the development of vancomycin resistance.
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