Detection and identification of staphylococcus aureus enterotoxins in some milk products and their handlers
EJMM-Egyptian Journal of Medical Microbiology [The]. 2013; 22 (2): 101-111
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| ID: emr-188940
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EMRO
Background: 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 S. aureus genome, new genes encoding enterotoxin-like superantigens have been identified. Milk and dairy products are frequently contaminated with enterotoxigenic S. aureus, which is often involved in staphylococcal food poisoning; these contaminations are either from animal or human sources
Aim of the work: To detect the presence and prevalence of coagulase positive S. aureus in milk, kariesh cheese and ice-cream samples and in nasal swabs and stool samples from milk handlers, and to detect types of S. aureus enterotoxins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis [SDS-PAGE], and to detect the type of enterotoxins genes by PCR
Material and Methods: 250 samples of Milk, ice-cream, kariesh cheese, nasal swabs and stool samples from milk 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 S. 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]
Results: Coagulase positive S. aureus isolates were detected in 82% of Staph colonized raw milk, 80% of Staph colonized ice-cream and 82.3% of Staph colonized kariesh cheese samples and 86.6% of Staph colonized nasal swabs, and 60% of Staph colonized stool samples; with 70.9% of total samples staph colonization exceeds the Egyptian standards. Collectively, 44.3% of coagulase positive S. aureus isolates were enterotoxigenic and the highest percentages were detected in raw milk taken directly from animals [75%] and kariesh cheese from street distributors [66.6%]. In all samples, the major classical enterotoxin genotype was SEA which was detected in 44.4% of toxigenic isolates. SEC was detected in 22.2% of isolates and SED in 18.5% of isolates. SEB could not be detected. For the newly described genes, SEG was detected in 7.4% of isolates and SEH in 7.4% of isolates
Conclusions: Raw milk and some dairy products in the markets in Assuit Governorate rural areas-Egypt, are contaminated with enterotoxigenic S. aureus. The most common type in both milk and dairy products as well as in nasal swabs and stool samples was SEA which is known to be less common among strains from animal origin than from human. Nasal and fecal carriage in human milk handlers is considered a primary source of contamination of milk and dairy products
Aim of the work: To detect the presence and prevalence of coagulase positive S. aureus in milk, kariesh cheese and ice-cream samples and in nasal swabs and stool samples from milk handlers, and to detect types of S. aureus enterotoxins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis [SDS-PAGE], and to detect the type of enterotoxins genes by PCR
Material and Methods: 250 samples of Milk, ice-cream, kariesh cheese, nasal swabs and stool samples from milk 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 S. 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]
Results: Coagulase positive S. aureus isolates were detected in 82% of Staph colonized raw milk, 80% of Staph colonized ice-cream and 82.3% of Staph colonized kariesh cheese samples and 86.6% of Staph colonized nasal swabs, and 60% of Staph colonized stool samples; with 70.9% of total samples staph colonization exceeds the Egyptian standards. Collectively, 44.3% of coagulase positive S. aureus isolates were enterotoxigenic and the highest percentages were detected in raw milk taken directly from animals [75%] and kariesh cheese from street distributors [66.6%]. In all samples, the major classical enterotoxin genotype was SEA which was detected in 44.4% of toxigenic isolates. SEC was detected in 22.2% of isolates and SED in 18.5% of isolates. SEB could not be detected. For the newly described genes, SEG was detected in 7.4% of isolates and SEH in 7.4% of isolates
Conclusions: Raw milk and some dairy products in the markets in Assuit Governorate rural areas-Egypt, are contaminated with enterotoxigenic S. aureus. The most common type in both milk and dairy products as well as in nasal swabs and stool samples was SEA which is known to be less common among strains from animal origin than from human. Nasal and fecal carriage in human milk handlers is considered a primary source of contamination of milk and dairy products
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Indice:
IMEMR
Type d'étude:
Diagnostic_studies
langue:
En
Texte intégral:
Egypt. J. Med. Microbiol.
Année:
2013