Open Veterinary Journal (Sep 2020)
Isolation of enterotoxigenic Staphylococcus aureus harboring seb gene and enteropathogenic Escherichia coli (serogroups O18, O114 and O125) from soft and hard artisanal cheeses in Egypt
Abstract
Background: Soft and hard artisanal cheeses are regularly consumed in Egypt. These products are usually processed from raw milk which may harbor many pathogenic and spoilage microorganisms. Aim: Evaluate the safety of some artisanal cheeses in Egypt such as Ras, Domiati and Mish through chemical and microbiological examination. Methods: One hundred and fifty random samples of traditional Ras, Domiati and Mish cheeses (50 each) were microbiologically and chemically analyzed. Counts of total bacteria, presumptive coliform, staphylococci, yeast and mold were estimated. Furthermore, isolation of Escherichia coli and Staphylococcus aureus was performed followed by PCR confirmation, isolates of E. coli were examined for presence of virulence genes on the other hand detection of the five classical enterotoxin genes of S. aureus was performed using multiplex PCR. Regarding chemical analysis moisture, salt and acidity content were measured. Correlations between chemical and microbial findings were investigated. Results: Mean counts of total bacteria, presumptive coliform, staphylococci, yeast and mold were (2×108, 3×106 and 1×107 ), (3×105, 5×10 and 5×102), (1×106, 4×105and 1×105), (3×105, 1×105 and 5×105) and (7×103, 4×103 and 3×104) for Ras, Domiati and Mish cheeses, respectively. Serological identification of suspected E. coli revealed that E. coli O125 was isolated from Ras and Domiati samples, E. coli O18 was recovered from Ras samples, while E. coli O114 was isolated from Mish samples. PCR results revealed that all detected isolates of E. coli were positive for both iss (increased serum survival) and fimH (type 1 fimbriae) genes. Concerning isolated S. aureus all examined products were harboring S. aureus enterotoxigenic strains with seb and sed genes were most common. The mean values of moisture, salt and acidity were (30.03, 56.44 and 58.70), (3.30, 6.63 and 7.56) and (0.65, 0.68 and 0.50) for Ras, Domiati and Mish cheeses, respectively. Conclusion: Enterotoxigenic S. aureus harboring seb gene and enteropathogenic E. coli (serogroups O18, O114 and O125) were frequently isolated from soft and hard artisanal cheeses in Egypt. Therefore, strict hygienic measures should be applied during their manufacture, handing and distribution.
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