Studia Universitatis Babeș-Bolyai. Biologia (Jun 2025)
Molecular detection of enterotoxin genes (sea and sec) in Staphylococcus aureus isolated from dairy products in Karaj, Alborz, Iran
Abstract
Staphylococcus aureus, a significant bacterial agent of food poisoning, particularly the strains producing enterotoxins, is a topic of paramount importance. The prevalence of these enterotoxins in the dairy industry, especially in regions like Karaj city, Alborz province, Iran, with its numerous industrial and traditional dairy companies, is a matter of great concern for public health. This study aims to evaluate the frequency of sea and sec genes among dairy products in Karaj, Iran. We collected 100 samples of industrial and traditional dairy products, including 25 samples of pasteurized milk, 25 samples of pasteurized ice cream, 25 samples of raw milk, and 25 samples of traditionally made ice cream, throughout Karaj, then transferred them into the laboratory, then cultured on the media containing mannitol salt agar and Brad Parker agar. Second, enzymatic tests, such as catalase and coagulase tests and biochemical and bacterial assessments, including mannitol fermentation and Gram staining methods, were employed to detect S. aureus contamination. Besides, the presence of sea and sec genes was assessed by PCR. Finally, the data were statistically analyzed using SPSS software. The results demonstrated that enzymatic and biochemical methods could detect 54 contaminated samples by S. aureus among 100 samples. However, as a reliable molecular technique, PCR detected 57 S. aureus-contaminated samples among all the tested samples. Moreover, it is indicated that 12 and 6 PCR-positive samples contained enterotoxin A and C types, respectively. In brief, the huge amounts of dairy products in Karaj are significantly contaminated by enterotoxin-producing strains of S. aureus, especially type A and C. Article history: Received 25 August 2024; Revised 25 October 2024; Accepted 17 January 2025; Available online 25 June 2025
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