Prevalence, Multidrug Resistance and Molecular Typing of MRSA in Retail Meat from Punjab, India.

OBJECTIVE: This study reports the prevalence of Methicillin-Resistant S. aureus (MRSA) in meat samples taken from Punjab, India.

METHODS: Classical microbiological methods were applied to isolate and identify the Staphylococcus aureus. These isolates were further subjected to Epsilometer test. PCR and sequencing were used to identify and characterize the antibiotic-resistant genes. The SCCmec typing, MLST and spa typing was done on the MRSA isolates.

RESULTS: A total of 408 meat and 101 swabs samples were processed for isolation of S. aureus. The phenotypic resistance of S. aureus isolates to penicillin was highest (90.97%), followed by ciprofloxacin (61.80%), tetracycline (45.14%), and erythromycin (11.11%). Isolates from chicken samples showed significantly (P <0.05) higher MIC for tetracycline than chevon and pork; and significantly higher MIC for trimethoprim-sulfamethoxazole and gentamicin than chevon and swab samples (P <0.05). None of the isolates was phenotypically resistant to vancomycin (MIC 0.5-2μg/ml). Most of the isolates (52.78%, 95%CI 44.63-60.93) were Multi-drug resistant (MDR) and carried resistance genes; penicillin (blaZ), oxacillin (mecA), gentamicin (aacA-aphD), erythromycin (ermB, ermC) and tetracycline (tetK, tetL, tetM). MRSA was found only in chicken samples (2.72%, 4/147). Seven S. aureus (5.34%) isolates were borderline oxacillin resistant (BORSA) with MIC ranging from 4-8μg/ml. All MRSA isolates in this study were SCCmec type V, pvl positive and spa type t442, but among these, three isolates were ST5. Their genotypic profile was mecA+ , blaZ+ , aacA-aphD+ , tetK+ , ermC+/- . Among the erythromycin-resistant isolates, 25% were MRSA. Out of them, 12.5% isolates expressed inducible macrolide lincosamide and streptogramin (MLSB ) phenotype (ERY+/CLI-, D+).

CONCLUSION: Our data confirm the presence of ST5, spa type t442 MRSA-SCCmecV-pvl+ and iMLSB- MRSA in meat samples indicating a potential role of meat in the dissemination of MDR S. aureus strains and successful MRSA lineages in Punjab.