Genotypic and Phenotypic-Based Assessment of Antibiotic Resistance and Profile of Staphylococcal Cassette Chromosome in the Methicillin-Resistant Recovered from Raw Milk.

BACKGROUND

Multidrug resistant methicillin-resistant (MRSA) bacteria are determined to be one of the chief causes of foodborne diseases around the world.

PURPOSE

This research was done to assess the genotypic and phenotypic profiles of antibiotic resistance and distribution of Staphylococcus cassette chromosome (SCC) types amongst the MRSA bacteria recovered from raw milk.

METHODS

Five-hundred and ninety raw milk samples were collected and examined. MRSA bacteria were recognized using susceptibility evaluation toward oxacillin and cefoxitin disks. Profile of antibiotic resistance genes and SCC types were determined using the PCR. Antibiotic resistance pattern of isolates was examined using the disk diffusion.

RESULTS

Thirty-nine out of 590 raw milk samples (6.61%) were positive for . Twenty-eight out of 39 (71.79%) bacteria were defined as MRSA bacteria. Raw buffalo (80%) milk samples had the maximum incidence of MRSA, while raw camel (33.33%) had the minimum. MRSA bacteria harbored the maximum incidence of resistance toward penicillin (100%), tetracycline (100%), erythromycin (82.14%), gentamicin (78.57%) and trimethoprim-sulfamethoxazole (78.57%). Incidence of resistance toward more than eight classes of antibiotic agents was 28.57%. The most frequently distinguished antibiotic resistance markers were (100%), (85.71%), (71.42%), (67.85%), (50%) and (42.85%). SCC IVa (29.62%), V (25%), III (14.81%) and IVb (11.11%) were the most frequently distinguished types.

CONCLUSION

Raw milk of dairy animals maybe sources of multidrug resistant MRSA which pose a hygienic threat concerning the consumption of raw milk in Iran. Nevertheless, further investigations are necessary to understand supplementary epidemiological features of MRSA in raw milk.