Co-occurrence of sea, sec, and tst Enterotoxin Genes in Staphylococcus aureus isolates From Clinical Sources

Document Type : Original Articles

Authors

1 Department of Microbiology, Ka.C., Islamic Azad University, Karaj, Iran.

2 Department of Microbiology, Faculty of Medicine, Guilan University of Medical Sciences, Rasht, Iran.

3 Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.

10.32598/ARI.81.1.3362

Abstract

Introduction: Staphylococcus aureus is a Gram-positive bacterium that can cause various diseases in specific conditions by secreting various toxins. Enterotoxins and toxins toxic shock syndrome toxin (TSST) play a major role in pathogenesis. Enterotoxins and TSST are pyrogenic super antigens that react with the MHC II molecule. The aim of this study was to investigate the frequency of the sea, sec, and tst genes in S. aureus isolated from clinical sources.
Materials & Methods: This study was performed on 100 S. aureus isolates from hospitals in Karaj, which were finally identified using biochemical methods. Antibiotics susceptibility testing was performed by disk diffusion on agar, and the multiplex polymerase chain reaction (PCR) method was used to identify sea, sec, and tst genes.
Results: The highest resistance was observed to penicillin (92%), while the lowest resistance was observed to vancomycin (0%), and 48 isolates (48%) were identified as multi-drug resistant (MDR). Although 86 isolates (86%) had at least one of the analyzed genes, only one (1%) isolate showed the presence of all three sea, sec, and tst enterotoxin genes, and 36% of isolates had the sea and tst genes. Among the 86 isolates, 79% contained the sea gene, 5% contained the sec gene, and 43% had the tst gene. Statistical analysis revealed a significant correlation between the presence of the tst gene and MDR isolates.
Conclusion: The presence of relevant genes in clinical isolates should be considered in disease control and management due to the importance of S. aureus enterotoxins and TSST genes and their role in the development and exacerbation of staphylococcal diseases. Additionally, the high prevalence of antibiotic-resistant isolates limits antibiotic treatment.

Keywords

Archives of Razi Institute
Volume 81, Issue 1
January and February 2026
Pages 65-72

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