Comparison
of Various Phenotypic
Methods and mecA Based PCR
for the Detection of MRSA
1359-1362
Correspondence
Pramodhini S.
Assistant Professor
Department of Microbiology,
Mahatma Gandhi Medical College and Research Institute,
Pillaiyarkuppam, Pondicherry – 607 402
Phone: +91 9445216145
E-mail: pramo4@yahoo.co.in
Background: Methicillin resistant Staphylococcus aureus (MRSA) is the most commonly emerging pathogen in community and hospital acquired infections. Hence, an accurate detection is not only important for the control of the infection, but also to control the endemicity of MRSA.
Aim: To evaluate the efficacy of various phenotypic methods with mecA based PCR to detect MRSA. We also studied the resistance pattern of the MRSA isolates. Settings and Design: This was a prospective study which was conducted at a tertiary care hospital.
Materials and Methods: A total of 55 S. aureus strains which were isolated from patients with superficial and deep abscesses were included in this study. Methicillin resistance which was determined by oxacillin disc diffusion, cefoxitin disc diffusion and the oxacillin screen agar test was compared with mecA based PCR.
Results: Among the 55 S . aureus isolates, 20 (36.4%) isolates were positive for the mecA gene by PCR. Both the cefoxitin disc diffusion and the oxacillin screen agar test showed 100% sensitivity and 100% specificity, while oxacillin disc diffusion showed 90% sensitivity and 100% specificity. The resistance percentage of the MRSA isolates to erythromycin, ciprofloxacin and amikacin were 80%, 30% and 25%, respectively.
Conclusion: Conventional MRSA detection assays like the cefoxitin disc diffusion test and the oxacillin screen agar test are simple and relatively cheap and can be used as alternatives to PCR for the detection of MRSA in resource constraint settings. Also, most of the MRSA strains in this study showed coresistance to many classes of antibiotics and thus they qualified as multi-drug resistant S. aureus.