Molecular detection of enterotoxin genes (sea and sec) in Staphylococcus aureus isolated from dairy products in Karaj, Alborz, Iran
DOI:
https://doi.org/10.24193/subbbiol.2025.1.06Keywords:
dairy products, enterotoxin A, enterotoxin C, polymerase chain reaction, Staphylococcus aureusAbstract
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
References
Abdurrahman, G., Schmiedeke, F., Bachert, C., Bröker, B. M. & Holtfreter, S. (2020). Allergy—a new role for T cell superantigens of Staphylococcus aureus? Toxins, 12(3), 176. https://doi.org/10.3390/toxins12030176
Ali, A. A., Altemimi, A. B., Alhelfi, N. & Ibrahim, S. A. (2020). Application of biosensors for detection of pathogenic food bacteria: a review. Biosens., 10(6), 58. https://doi.org/10.3390/bios10060058
Almutawif, Y., Hartmann, B., Lloyd, M., Lai, C. T., Rea, A. & Geddes, D. (2019). Staphylococcus aureus enterotoxin production in raw and pasteurized milk: The effect of selected different storage durations and temperatures. Breastfeed. Med., 14(4), 256-261. https://doi.org/10.1089/bfm.2018.0227
Al-Nabulsi, A. A., Osaili, T. M., AbuNaser, R. A., Olaimat, A. N., Ayyash, M., Al-Holy, M. A. & Holley, R. A. (2020). Factors affecting the viability of Staphylococcus aureus and production of enterotoxin during processing and storage of white-brined cheese. J. Dairy Sci., 103(8), 6869-6881. https://doi.org/10.3168/jds.2020-18158
Beveridge, T. J (2001). Use of the Gram stain in microbiology. Biotech. Histochem., 76(3), 111-118. https://doi.org/10.1080/bih.76.3.111.118
El-Mokadem, E. A., El-Leboudy, A. A. & Amer, A. A. (2020). Occurrence of Enterobacteriaceae in Dairy Farm Milk. Alex. J. Vet. Sci., 64(2), 66-71. https://doi.org/10.5455/ajvs.254389
Fabijan, A. P., Lin, R. C., Ho, J., Maddocks, S., Ben Zakour, N. L. & Iredell, J. R. (2020). Safety of bacteriophage therapy in severe Staphylococcus aureus infection. Nat. Microbiol., 5(3), 465-472. https://doi.org/10.1038/s41564-019-0634-z
Forouzani‐Moghaddam, M. J., Habibi, S., Hosseini‐Safa, A., Khanaliha, K., Mokarinejad, R., Akhoundzadeh, F. & Oshaghi, M. (2024). Rapid detection of major enterotoxin genes and antibiotic resistance of Staphylococcus aureus isolated from raw milk in the Yazd province, Iran. Vet. Med. Sci., 10(3), e1407. https://doi.org/10.1002/vms3.1407
Grispoldi, L., Karama, M., Armani, A., Hadjicharalambous, C. & Cenci-Goga, B. T. (2021). Staphylococcus aureus enterotoxin in food of animal origin and staphylococcal food poisoning risk assessment from farm to table. Ital. J. Anim. Sci., 20(1), 677-690. https://doi.org/10.1080/1828051X.2020.1871428
Harijani, N., Wandari, A., Effendi, M. H. & Tyasningsih, W. (2020). Molecular Detection of Encoding Enterotoxin C Gene and Profile of Antibiotic Resistance on Staphylococcus Aureus Isolated from Several Dairy Farms in East Java, Indonesia. Biochem. Cell. Arch., 20(1), 3081-3085. http://repository.unair.ac.id/id/eprint/101305
Hu, D. L., Li, S., Fang, R. & Ono, H. K. (2021). Update on molecular diversity and multipathogenicity of staphylococcal superantigen toxins. Anim. Dis., 1(1), 7. https://doi.org/10.1186/s44149-021-00007-7
Lally, R. T., Ederer, M. N. & Woolfrey, B. F. (1985). Evaluation of mannitol salt agar with oxacillin as a screening medium for methicillin-resistant Staphylococcus aureus. J. Clin. Microbiol., 22(4), 501-504. https://doi.org/10.1128/jcm.22.4.501-504.1985
Nouri, A., Ahari, H. & Shahbazzadeh, D. (2018). Designing a direct ELISA kit for the detection of Staphylococcus aureus enterotoxin A in raw milk samples. Int. J. Biol. Macromol., 107, 1732-1737. https://doi.org/10.1016/j.ijbiomac.2017.10.052
Osman, K. M., Pires, Á. D. S., Franco, O. L., Orabi, A., Hanafy, M. H., Marzouk, E. & Elbehiry, A. (2020). Enterotoxigenicity and antibiotic resistance of coagulase-negative staphylococci isolated from raw buffalo and cow milk. Microb. Drug. Resist., 26(5), 520-530. https://doi.org/10.1016/j.yclnex.2017.05.001
Parker, M. T. & Hewitt, J. H. (1970). Methicillin resistance in Staphylococcus aureus. The Lancet, 295(7651), 800-804. https://doi.org/10.1016/S0140-6736(70)92408-6
Pereira, C. T. M., de Oliveira, D. S. V., Veloso, V. S., Silva, S. D. S. P., Santos, L. S., Lima, A. F. & dos Santos Soares, M. J. (2018). Microbiology quality, detection of enterotoxin genes and antimicrobial resistance of Staphylococcus aureus isolated from milk and Coalho cheese. Semin. Ciênc. Agrár., 39(5), 1957-1967. https://doi.org/10.5433/1679-0359.2018v39n5p1957
Reiner, K. (2010), Catalase test protocol. American Society for Microbiology. https://asm.org/getattachment/72a871fc-ba92-4128-a194-6f1bab5c3ab7/Catalase
Sperber, W. Z. & Tatini, S. R. (1975). Interpretation of the tube coagulase test for identification of Staphylococcus aureus. Appl. Microbiol., 29(4), 502-505. https://doi.org/10.1128/am.29.4.502-505.1975
Tilocca, B., Costanzo, N., Morittu, V. M., Spina, A. A., Soggiu, A., Britti, D. & Piras, C. (2020). Milk microbiota: Characterization methods and role in cheese production. J. Proteom., 210, 103534. https://doi.org/10.1016/j.jprot.2019.103534
U.S. Dept. of Health and Human Services, Public Health Service and Food and Drug Admin. Grade “A” Pasteurized Milk Ordinance. 2017 Revision. https://www.fda.gov/media/114169/download
Vargová, M., Zigo, F., Výrostková, J., Farkašová, Z. & Rehan, I. F. (2023). The biofilm-producing ability of Staphylococcus aureus is obtained from the surfaces and milk of mastitic cows. Vet. Sci., 10(6), 386. https://doi.org/10.3390/vetsci10060386
Wang, H., Hecht, S., Kline, D. & Leber, A. L. (2019). Staphylococcus aureus and methicillin resistance detection directly from pediatric samples using PCR assays with differential cycle threshold values for corroboration of methicillin resistance. J. Microbiolog. Meth., 159, 167-173. https://doi.org/10.1016/j.mimet.2019.01.009
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