Spa Typing and Prevalence of Methicillin-Resistant Staphylococcus aureus Isolated in Retail Meats from Silchar, Assam, India

Background: The study involves the presence of Methicillin-resistant Staphylococcus aureus (MRSA) in animal food origin which is a growing concern as their presence makes them highly pathogenic and difficult to treat. Materials and methods: A total of 414 samples consisting of pork 50 (12.07%), chicken 86 (20.77%), beef 74 (17.87%), mutton 100 (24.15) and fish 104 (25.12%) were randomly purchased from different retail meat shops located at Silchar, Assam, India. All the isolates were tested against cefoxitin (30µg) and oxacillin (1µg) and classified as MRSA isolates. Spa typing of randomly selected 136 MRSA isolates was done followed by antimicrobial susceptibility testing. Results: Overall prevalence rate of MRSA was observed as 38/104 (36.53%) in fish, 33/86 (38.37%) in chicken, 26/74 (35.13%) in beef, 26/100 (26%) in mutton and 13/50 (26%) in pork. Of 136 MRSA isolates, only 12 isolates (8.82%) that harboured the spa gene amplified at 371bp. The frequently found environmental and human associated spa type t021 (clonal complex CC30, 83.33%) and a less frequently found spa type t448 (16.66%) were recovered from chicken, mutton, beef and pork. All tested MRSA isolates were found to be 100% resistant to cefoxitin followed by oxacillin and clindamycin but resistance to other antibiotics were variable. Conclusion: This is the first pilot study to be conducted in Silchar retail meat markets demonstrating the occurrence of MRSA in chicken, mutton, beef, pork and fish, thus, we strongly recommend regular monitoring and surveillance, implementation of good hygienic practices be incorporated to control the dispersion of MRSA to the community.