Isolation of Enterotoxin Producing Methicillin Resistant Staphylococcus aureus from Chicken Nugget Samples in Isfahan. 2019

Methicillin resistant Staphylococcus aureus (MRSA) harbor genes encoding a broad spectrum of virulence factors such as different enterotoxins which enable them to produce a variety of diseases in humans. These bacteria are found extensively in meat and ready to eat (RTE) meat products. The aim of this study was to assess the presence of enterotoxin producing MRSA isolates in chicken nugget samples in Isfahan.

During May and October 2019 a total of 12 chicken nuggets from 2 different companies were collected in Isfahan. Samples were prepared and cultured on Baird-Parker agar supplemented with oxacillin and black colonies with halo were selected and identified as MRSA using specific primers for nucA and mecA genes. For typing of MRSA strains, SCCmec typing and prophage typing methods using the separate multiplex-PCR assays were employed. Moreover, the presence of different enterotoxin genes was tested by the separate multiplex-PCR assays.

Out of the 12 chicken nuggets, 5 (42%) samples were contaminated with MRSA isolates and a total of 93 strains were identified using specific primers for nucA and mecA. The results of SCCmec typing showed that 3 different types II, III and V were present among MRSA strains, in which type III was the dominant one. Also, 6 different prophage types and 3 prophage patterns were identified among the strains. Moreover, 13 genes encoding different enterotoxins were also detected in which, sea, sek and seq genes were present among all strains.

The results of the present study revealed the high prevalence of enterotoxin producing MRSA strains in chicken nugget samples indicating the importance of hygiene systems for producing of such RTE products