Immunochemical and PCR analysis of Staphylococcus aureus Enterotoxin B (SEB) in milk and fruit juices collected in Lahore, Pakistan

Enterotoxins secreted by S. aureus are known as a food-poisoning agent that is associated with various gastro-intestinal pathological conditions. In this study, a one-step immunodetection method was devised for routine checking of SEB in milk and fruit juices available locally. Antibodies against recombinant SEB were raised, purified, and cross reactivity was checked against clinically important bacteria (Shigella flexneri, Streptococci, Salmonella typhi, Klebsiella and Bacillus subtilis). Purified anti-SEB antibodies were conjugated with gold nanoparticles (Ab-GNPs) for direct detection of SEB in samples. SEB (33%, 4.76% and 15%) was found in non-sterilized milk (118), sterilized milk (42) and juices (60), respectively. Coagulase, MSA tests and PCR amplification of 725 bp of the SEB gene confirmed the presence of S. aureus in the collected samples positive for SEB. Immunoassay is easy, reliable and less time consuming and will be helpful to detect the SEB in food samples at local level