Distribution of genes encoding virulence factors of Shigella strains isolated from children with diarrhea in southwest Iran


This study aimed to investigate the distribution of virulence factor genes in Shigella strains isolated from children with diarrhea in the southwest, Iran. In this cross-sectional study, 1530 diarrheal stool specimens were collected from children aged under 15 years. The Shigella strains were identified by biochemical methods and polymerase chain reaction (PCR). Subsequently, all Shigella isolates were evaluated by PCR for the presence of nine virulence genes ipaH (responsible for dissemination from cell to cell), ial (responsible for epithelial cell penetration), sat (displays cytopathic activity in several intestinal cell lines), sigA (toxic to epithelial cells), pic (associated with colonization), pet (cytotoxic for epithelial cells), sepA (contribute to intestinal inflammation and colonization), virF and invE (regulatory proteins). A total of 91 isolates including 47 S. flexneri, 36 S. sonnei, and 8 S. boydii were identified. All isolates were positive for the ipaH gene. The other genes include ial, virF, invE, sigA, sat, sepA, pic and pet found in 84.6%, 72.5%, 68.1%, 62.6%, 51.6%, 39.5%, 37.3% and 28.5% of the isolates, respectively. The results showed a high distribution of virulence genes among Shigella strains in our region. It seems that for different Shigella spp. different virulence factors contribute to pathogenesis. The current study provided insights into some baseline information about the distribution of some virulence genes of Shigella isolates in Southwest Iran.

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This work was supported by the Vice-Chancellor for Research grant (Grant No. 98U-603) of Abadan University of Medical Science. The authors of this manuscript would like to acknowledge the laboratory and nursing personnel of children and infants ward in teaching hospitals in Ahvaz, Abadan and Khorramshahr, who assisted to collect the clinical specimens.

Author information




MA developed the original idea and the protocol, performed the experiments, KA was involved in data collection, wrote the preliminary draft and analyzed the data, NJ revised the manuscript.

Corresponding author

Correspondence to Maryam Afzali.

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Ethical approval

The study was approved by the Research Ethics Committee of the Abadan Faculty of Medical Sciences (Ethical code: IR. ABADANUMS.REC1398.073), Abadan, Iran. Written informed consent was obtained from all the children’s parents. Our manuscript has been already submitted to a pre-print platform (Research Square), providing the DOI (https://doi.org/10.21203/rs.3.rs-29988/v1) and licensing information.

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Jomehzadeh, N., Ahmadi, K., Javaherizadeh, H. et al. Distribution of genes encoding virulence factors of Shigella strains isolated from children with diarrhea in southwest Iran. Mol Biol Rep 48, 1645–1649 (2021). https://doi.org/10.1007/s11033-021-06170-x

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  • Shigella
  • Diarrhea
  • Virulence factor
  • Polymerase chain reaction