Molecular investigation of Tsst, Eta, and Etb Genes in Staphylococcus aureus isolated from impetigo patients among children in Al-Diwaniyah city, Iraq

Document Type : Research Paper

Authors

1 Department of Pathological Analysis, College of Science, University of Al-Qadisiyah, Iraq

2 Department of Biology, College of Education, University of Al-Qadisiyah, Iraq

10.22103/jab.2025.25015.1682

Abstract

Objective
Staphylococcus aureus is a versatile and opportunistic pathogen responsible for a broad spectrum of human diseases ranging from superficial skin infections to life-threatening systemic situations. Among its many clinical manifestations, impetigo a contagious skin infection primarily affecting children is commonly related with S. aureus as a principal causative agent. The prevalence of S. aureus in skin and soft tissue infections has become a growing public health concern, especially in pediatric populations and in regions with restricted access to advanced healthcare resources. The current investigation aimed to investigate the molecular presence of the tsst, eta, and etb genes in S. aureus isolates achieved from children diagnosed with impetigo in Al-Diwaniyah City,. By combining 16S rRNA gene amplification with virulence gene profiling, this research contributes to a deeper understanding of the molecular epidemiology and pathogenic traits of S. aureus in a vulnerable patient population.

Materials and methods
This investigation was managed on clinical isolates achieved from children diagnosed with impetigo and attending dermatology clinics in Al-Diwaniyah City, Iraq. Totally 21 swab samples were gathered from infected skin lesions applying sterile cotton swabs. Genomic DNA was extracted from affirmed S. aureus isolates. To affirm the identity of the isolates, PCR was carried out targeting the 16S rRNA gene. The presence of tsst, eta, and etb genes was identified by conventional PCR applying gene-specific primers.
Results
All Staphylococcus aureus isolates demonstrated a distinct 1,500 bp band upon PCR amplification of the 16S rRNA gene, affirming successful amplification of the target gene. This result also indicated the high quality of the extracted bacterial DNA and the specificity of the primers applied. The conserved nature of the 16S rRNA gene reinforces its reliability as a molecular marker for bacterial identification. In addition, the presence of exfoliative toxin genes (eta, etb, and tsst-1) was evaluated applying PCR. Each gene generated a distinct amplification pattern. Among the 21 clinical isolates, 11 were positive for the tsst-1 gene. The eta and etb genes were also detected but in varying frequencies, suggesting differential distribution of these virulence factors among the isolates.

Conclusions
This investigation highlights the molecular presence of key virulence genes (tsst-1, eta, and etb) in Staphylococcus aureus isolates from impetigo cases in children. The detection of these toxin genes, particularly the high prevalence of tsst-1, underscores the pathogenic potential of circulating strains and reinforces the importance of molecular screening in clinical diagnostics and infection control strategies.

Keywords

References

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Agricultural Biotechnology Journal
Volume 17, Issue 2
May 2025
Pages 325-342

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