Prevalence and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus in Milk and Meat of Small Ruminants in Southern Tamil Nadu

Abstract:

Methicillin-resistant Staphylococcus aureus (MRSA) is a widely recognized pathogen of global concern. A total of 120 samples comprising raw milk (n=60) and meat (n=60) were collected from Tirunelveli, Tuticorin, Tenkasi and Kanniyakumari districts to study the prevalence and molecular characteristics of S. aureus in milk and meat of small ruminants. Isolation was performed using Baird Parker Agar followed by Gram’s staining, biochemical tests and confirmation with HiStaph™ test kit. Genomic DNA was extracted and presumptive isolates were confirmed by PCR targeting 16S rRNA and nuc genes. Detection of mecA and femB genes was used to identify MRSA, while enterotoxin genes (sea, seb, sec, sed, see) were screened using multiplex PCR. Out of 120 samples, 31 (25.83%) were positive for S. aureus, including 23 from milk and 8 from meat. Among these, 17 isolates (54.83%) harbored both mecA and fem B genes, confirming MRSA, while enterotoxin genes sea and sed were detected in 6.45% and 3.22% isolates, respectively. A crucial prevalance of MRSA and enterotoxigenic S. aureus in small ruminant derived milk and meat in southern Tamil Nadu, is highlighted in our study. Hence, regular monitoring and implementation of food safety measures are essential to mitigate the threat of antimicrobial resistance transmission through the food chain.