Characteristics of enterotoxin Producing methicillin Resistant Staphylococcus aureus Strains Isolated from Meat in Tehran, Iran

Background and Objectives: Methicillin resistant S. aureus (MRSA) strains have been associated with infections in animals, poultry, slaughterhouse workers and veterinarians and, in general, people who are in close contact with these domestic animals or their products. Moreover, MRSA is a leading cause of foodborne bacterial intoxications and has been found in different animals, raw retail meat products and raw chicken meat. In this study, we investigated the clonality, antibiotic susceptibility and presence of different enterotoxins genes among MRSA strains isolated from fresh raw meat samples in Tehran, Iran during 2016. Materials and Methods: A total of 131 fresh raw meat samples (beef, chicken and turkey) were collected from grocery stores in Tehran, Iran, at 6 different time intervals. The susceptibility of 49 MRSA strains to 15 different antibiotics, clonality using biochemical Phene plate typing (PhP), occurrence of staphyloccus cassette chromosome mec (SCCmec) gene types and the presence of different enterotoxin genes among these isolates were studied. Results: Amongst all meat samples, 47, 30 and 27% of beef, chicken and turkey samples were MRSA positive. PhenePlate (PhP typing) revealed the presence of 12 PhP types consisting of 5 common types (CTs) and 7 single types (STs), and 86% of strains harbored staphylococcal cassette chromosome mec (SCCmec) type III and type 3 cassette chromosome recombinases (ccr). Moreover, SCCmec type IVa was positive in all isolates with SGA prophage types. High level resistance to ciprofloxacin, erythromycin, tobramycin and kanamycin was also observed and the rate of resistance to most of the antibiotics tested among chicken samples was higher than the others. Out of 11 different enterotoxins genes found, sea, sek and seq were the dominant ones in all strains. Conclusion: Our results indicate the presence and persistence of highly resistant clonal groups of enterotoxin producing MRSA in the meat samples. These isolates had PhP and SCCmec types and prophage patterns which were similar to the clinical isolates previously reported in Iran, supporting the notion of dissemination of the MRSA in the hospital, community, as well as food products in Iran.