Prevalence of Shiga Toxin-Producing and Enteropathogenic Escherichia coli in Wild and Pet Birds in Iran

A Koochakzadeh,M Askari Badouei,Mr Ehsan,M Soltani,T Zahraei Salehi,S Aghasharif

doi:10.1590/1516-635x1704445-450

Abstract

The aim of this study was to investigate the prevalence of Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) strains and to identify the stx gene types in wild captive and companion birds. In total,657 E. coli isolates from 219 birds belonging to 38 different species were investigated for the presence of STEC and EPEC strains. It was shown that five birds (2.28%) carried strains positive for one or more of the virulence factors investigated. The results indicated that 1.8% (n=4) and 0.45% (n=1) of the birds carried STEC and EPEC strains, respectively. All STEC strains harbored the stx2f and eae genes and this finding reveals the role of other birds, in addition to pigeons, as reservoirs of STEC. The only EPEC strain in this study was isolated from a Myna. Based on our knowledge, this is the first report of Stx2f-producing STEC in Geese, Duck and Lesser kestrel. In conclusion, the results indicate a low frequency of STEC carriage in wild and companion birds, and point out the need of additionally screening for the presence of stx2f in all the eae-harboring strains from birds.

Highlights

Escherichia coli belongs to the intestinal bacterial flora in most animal species
Among the 657 E. coli isolates investigated for the presence of the eae gene, five isolates, which were originated from five different birds belonging to four different species, resulted positive (Figure 1; Table 1)
Four E. coli strains were isolated from four birds belonging to three different species including harbored both stx2f and eae genes, while one isolate obtained from a Myna harbored only the eae (Figure 1; Table 1)

Summary

Introduction

Escherichia coli belongs to the intestinal bacterial flora in most animal species. most E. coli strains are nonpathogenic, some strains may cause diarrhea and other intestinal diseases (Law, 1988). EPEC strains may express the outer membrane protein intimin (94-97 KDa), which is encoded by the eae gene and causes the attaching and effacing lesions in the epithelial cells of the intestine and resulting diarrhea in humans (Adu-Bobie et al, 1998). Shiga toxin-producing Escherichia coli strains (STEC) harbor Shiga toxin (stx) genes (Kobayashi et al, 2002) and are able to cause diarrhea in humans and some animal species. They are linked to hemorrhagic colitis (HC), hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) in humans, which require hospitalization and intensive care with considerable mortality in children and elderly patients (Gyles, 2007). The ability of STEC strains to cause serious diseases in humans is related to the production of one or more Shiga toxins (Stx, Stx, or their variants), which inhibit protein synthesis in host cells leading to cellular damage (O’Brien et al, 1992)

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Results

Conclusion