Phylogenetic Diversity of sea and seb Gene Encoding Enterotoxin in Staphylococcus aureus Isolated from Animal-Origin Foods

Abstract

Staphylococcus aureus is an opportunistic pathogen that causes multiple diseases in both humans and animals. It is considered a major cause of foodborne illnesses. The study was designed to investigate the prevalence and phylogenetic diversity of sea and seb gene encoding enterotoxin in Staphylococcus aureus isolated from animal-origin foods. A total of 150 samples were collected, including bovine milk, poultry meat, and chevon. The samples were subjected to cultural isolation and identification on Baird-Parker medium, followed by molecular detection of the thermonuclease (nuc) gene. The confirmed S. aureus isolates were further screened for Staphylococcal enterotoxin (SE) genes by singleplex PCR and studied the genetic relationship of the strain. S. aureus isolated on Baird-Parker medium accounted to 44% (66/150). A total of 16/50 (32%) milk samples, 18/50 (36%) poultry meat and 21/50 (42%) chevon were positive by the nuc gene. The frequency of SE genes in bovine milk, poultry meat and chevon was found to be 37.5% (6/16), 50% (9/18) and 28.57% (6/21), respectively. The prevalence of the enterotoxin gene sea and seb was 23.63% and 14.54 %, respectively. Phylogenetic analysis showed homology with Homo sapiens, which indicated the possibility of zoonotic transmission. These entero-toxigenic genes might transfer genes from animal foods to humans. Based on these findings, our data confirms the widespread proliferation of enterotoxigenic S. aureus strains in foods of animal origin in Nagpur and highlights major public health risks linked to the consumption of these enterotoxin gene-contaminated S. aureus foods, such as bovine milk, poultry meat, and chevon, emphasizing the need for surveillance and molecular characterization of these virulence genes to mitigate foodborne health risk.