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Prevalence of Shiga Toxin-Producing Escherichia coli in a Diarrheagenic Tunisian Population, and the Report of Isolating STEC O157:H7 in Tunis

Current Microbiology volume 53, pages 483–490 (2006)Cite this article

Abstract

In Mellassine (a major city in the state of Tunis) and Ben Arous state (south east of Tunis), a total of 212 stool samples were collected from children and adults (symptomatic and asymptomatic groups) between November 2001 and November 2004. Three hundred and twenty-seven E. coli strains were isolated and studied, to look for shiga toxin-producing Escherichia coli (STEC) strains, which were further analysed to investigate and determine clonal relationship among Tunisian STEC strains isolated from different sources (diarrheal cases and food products). They were analysed to characterize their serotypes, virulence genes by PCR, cytotoxic effect on Vero cell, plasmid profiles, and pulsed-field gel electrophoresis (PFGE) patterns. Eleven isolates (10 nontypeable, one O157:H7) carried stx gene and shared Stx restriction fragment length polymorphism (RFLP) patterns (stx1 +, stx2 +). Seven of these strains were isolated from acute diarrheal cases, and four were isolated from a control group (among which the only isolated STEC O157:H7). Two of the STEC strains harboured both eae and ehxA genes. Analysis of the cytotoxic effect on Vero cells showed that a correlation exists between carrying stx1 +, stx2 + genes and cytotoxicity. Also a correlation was noticed between STEC strains recovered from different sources regarding plasmid profiles and PFGE patterns. All stool samples positive for STEC were nonbloody. None of the STEC-positive patients developed severe diseases. These data demonstrate that although STEC is not a major cause of acute diarrhea in Tunis, it should not be overlooked. Measures should be taken to improve the detection and isolation of STEC from acute diarrheal cases as well as carriers.

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Acknowledgments

We thank Dr. Fessi Safwan (Service régional de l’hygiène du Ben Arous), Dr. Chadlia Koubaa (PMI Mellassine), Dr. Noureddine Ben Jemmaa (CSB du gouvernorat de Ben Arous), Pr. Amel Kechrid (Hôpital d’enfants), and Pr. Taoufik ben Chaâbane (Hôpital la Rabta-service infectieux) for their contribution in collecting the samples. We further thank Pr. Assia Ben Hasen (Centre National de Greffe de Moelle Osseuse, Tunis, Tunisia) for her technical assistance. We are grateful to Dr. Francine Grimont, directeur adjoint du Centre National de Référence des Escherichia coli et shigella, Unité Biodiversité des bactéries Pathogènes Emergentes- Paris, France, for supplying the reference strains.

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Affiliations

  1. Laboratoire de Contrôle des Eaux et Denrées Alimentaires, Institut Pasteur de Tunis, Tunis, Tunisia

    Nazek Al-Gallas & Ridha Ben Aissa

  2. Laboratoire de Virologie Clinique, Institut Pasteur de Tunis, Tunis, Tunisia

    Olfa Bahri

Authors
  1. Nazek Al-Gallas
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  2. Olfa Bahri
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  3. Ridha Ben Aissa
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Corresponding author

Correspondence to Ridha Ben Aissa.

Additional information

This work was conducted in Laboratoire de Contrôle des Eaux et Denrées Alimentaires de l’Institut pasteur de Tunis, Tunis, Tunisia.

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Al-Gallas, N., Bahri, O. & Aissa, R.B. Prevalence of Shiga Toxin-Producing Escherichia coli in a Diarrheagenic Tunisian Population, and the Report of Isolating STEC O157:H7 in Tunis. Curr Microbiol 53, 483–490 (2006). https://doi.org/10.1007/s00284-006-0184-5

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  • DOI: https://doi.org/10.1007/s00284-006-0184-5

Keywords

  • Stool Sample
  • Hemolytic Uremic Syndrome
  • Shiga Toxin
  • Acute Diarrhea
  • Plasmid Profile