Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 13 1 2021 02 10 31 36 Anitha Madhavan Department of Microbiology, Government TD Medical College, Alappuzha, Kerala, India Arun Sachu Department of Microbiology, Believers Church Medical College, Thiruvalla, Kerala, India Anukumar Balakrishnan Department of Virology, National Institute of Virology, Alappuzha, Kerala, India Anu Vasudevan Department of Biostatistics, Amrita Institute of Medical Sciences and Research Centre, Kochi, Kerala, India Sobha Balakrishnan Department of Microbiology, Government TD Medical College, Alappuzha, Kerala, India Jayalakshmi Vasudevapanicker Department of Microbiology, Government TD Medical College, Alappuzha, Kerala, India 2020 05 03 2020 11 26 Background and Objectives: Resistance to methicillin in methicillin resistant strains of Staphylococcus aureus (MRSA) is due to the presence of mec-A gene ,which encodes a low affinity penicillin binding protein (PBP)-2a or PBP2. Accurate and rapid identification of MRSA in clinical specimens is essential for timely decision on effective treatment. The aim of the study was to compare three different methods for detection of MRSA namely cefoxitin disc diffusion, CHROM agar MRSA and VITEK-2 susceptibility with PCR which is the gold standard reference method and to find the antibiotic susceptibility pattern of these isolates by VITEK-2. Materials and Methods: A Total of 100 non-duplicate S. aureus isolates were collected from different clinical samples among both outpatient and inpatients. Detection of MRSA among these isolates was done by cefoxitin disc diffusion, VITEK-2, CHROM agar MRSA and PCR. Results: The sensitivity and specificity of cefoxitin disc diffusion and Vitek was found to be 97.2% and 100%, while that of CHROM agar was found to be 100% and 78.6%. The overall prevalence of MRSA in our study by PCR was 72%. Conclusion: Based on the findings in our study, isolates which show cefoxitin zone diameter < 22 mm can be reported as MRSA. However, those isolates which have a zone diameter between 22-24 mm, should ideally be confirmed by PCR. https://ijm.tums.ac.ir/index.php/ijm/article/view/2612 https://ijm.tums.ac.ir/index.php/ijm/article/download/2612/1313