Molecular Identification of Enterotoxigenic Genes from Staphylococcus Aureus Isolates of Soy Milk Sold in Enugu Metropolis

Soy milk is an excellent food beverage and at the same time harbors pathogenic bacteria due its nutritional contents. Staphylococcus aureus as one of the pathogens produces enterotoxins that cause food poisoning which are of public health importance. The study aimed at determining the molecular identification of enterotoxigenic genes from Staphylococcus aureus isolates of soy milk sold in Enugu Metropolis. The isolates were identified and characterized using standard microbiological and molecular methods. A total of fifty (50) soy milk samples were collected within Enugu metropolis. The average total viable counts ranged from 4.1×10 2 cfu/ml to 1.0×10 2 cfu/ml. Out of fifty (50) soy milk samples collected, 42 (84%) were Staphylococcus aureus while 8 (16%) were negative. Out of 42 (84%) positive samples, 30 (60%) were coagulase -positive Staphylococcus aureus and 12 (24%) were coagulase-negative Staphylococcus aureus . Polymerase chain reaction (PCR) revealed the presence of Staphylococcus aureus using 16SrRNA gene at 1500bp and classical enterotoxin genes (SEA-SEE) respectively in all the three isolates examined. It was observed that the isolate A had 94.14% pairwise similarity with Staphylococcus strain KKP3462, isolate B had 92.32% similarity with Staphylococcus strain 2288 and isolate C had 94.8% similarity with Staphylococcus strain IDS-GIS36. The phylogenetic relatedness revealed that the isolates are related genotypically. Although the soy milk samples had low bacterial counts, the presence of enterotoxigenic Staphylococcus aureus highlights potential public health risks. These findings emphasize the need for continuous monitoring, strict hygienic practices and effective quality control measures in soy milk production to ensure consumer safety.