Detection of Staphylococcus Aureus Enterotoxins in milk, milk products as well as milk handlers in Sharkia governorate [electronic resource].
الكشف عن السموم المعوية لميكروب ستافيلوكوكس أوريس في الألبان ومنتجاتها والقائمين بتداولها في محافظة الشرقية.
- p.417-426.
Includes references.
Staphylococus aureus may contain one or more genes that encode staphylococcal enterotoxins (SE) that cause food poisoning. The previously known toxins were the five major classical types; however, with the extensive analysis of the Staph. aureus genome, new genes encoding enterotoxia-like superantigens have been identified. Milk and dairy products are frequently contaminated with enterotoxigenic Staph. aureus, which is often involved in staphylococcal food poisoning; these contaminations are either from animal or human sources. This work aimed to detect types of enterotoxins produced by Staph, aureus isolated from milk, kariesh cheese and ice-cream samples and from nasal swabs got from food handlers, the sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and PCR was used. In this work, 450 samples of Milk, ice-cream, kariesh cheese and nasal swabs from food handlers were examined for the presence of Coagulase positive Staph. aureus, using Mannitol salt agar, Baird-Parker agar, tube coagulase test, and latex agglutination test for protein A and capsular polysaccharides. Confirmed Staph. aureus isolates were examined for the production of SEs using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), and the type of SE genes by polymerase chain reaction (PCR). The Coagulase positive Staph. aureus isolates were detected in 84% of Staph colonized raw milk, 87.5% of Staph colonized ice-cream and 92.8% of Staph colonized kariesh cheese samples and 50% of Staph colonized nasal swabs, with 62.5% of total staph colonization which exceeds the Egyptian Standards. Collectively, 49.5% of coagulase positive Staph. aureus isolates were enterotoxigenic and the highest percentages were detected in raw milk taken directly from animals (68.7%) and kariesh cheese from street distributors (65.7%). In all samples, the major classical enterotoxin genotype was SEA which was detected in 33 isolates of toxigenic isolates. SEC was detected in 17 isolates and SED in II isolates. SEB could not be detected. For the newly described genes, SEG was detected in II isolates and SEH in 8 isolates. Mixed forms were found in 25 isolated of toxigenic isolates and four strains can’ied undescribed genes. Therefore we concluded that: Raw milk and some dairy products in the markets in Sharkia Governorate, Egypt are contaminated with enterotoxigenic Staph. aureus. The most common type in both milk and dairy products as well as in nasal swabs was SEA which is known to be less common among strains from animal origin than from human. Nasal carriage in human food handlers is considered a primary source of contamination of milk and dairy products.