Frequency of k99, stx1 and stx2 virulence factors in Escherichia coli isolated from diarrheic and clinically healthy suckling calves in Sistan and Baluchistan province, Iran

Document Type: Original Articles

Authors

1 Faculty of Veterinary Medicine, University of Zabol, Zabol, Sistan & Baluchistan, Iran

2 Department of Pathobiology, Faculty of Veterinary Medicine, University of Zabol, Zabol, Sistan & Baluchistan, Iran

Abstract

Understanding the frequency of virulence factor-encoding genes is essential in assessing the proportion of carriage. It is also required in characterization of major unique antigens that are useful in development of effective immunological-based preventive measures. The aim of the current study was to evaluate the frequency of three encoding-virulence genes associated with Enterotoxigenic and Shigatoxigenic Escherichia coli pathotypes (k99, stx1 and stx2) in North of Sistan and Baluchistan province, Iran. The frequency of k99, stx1, and stx2 was determined via PCR among Escherichia coli (E. coli) isolates collected from feces of the clinically healthy suckling (n=50) and diarrheic calves (n=50). k99 gene was absent in all isolates. The frequency of the E. coli contained either of stx1, stx2, or both stx1 and stx2 was 8, 14, and 4%, respectively, in clinically healthy suckling calves (p>0.05), compared to 24, 16, and 6% in diarrheic animals (p<0.05). Among the three studied genes, frequency of E. coli isolates containing stx1 was statistically different between clinically healthy suckling and diarrheic calves. While findings of our work indicated k99 does not appear to be a major fimbrial antigen-encoding gene in ETEC E. coli population in the region, we assume in any health measure intended to control the pathogen, other genes involved with encoding fimbriae, are also required to be considered. The noticeable high frequency of E. coli isolates bearing stx1 and/or stx2 virulence elements both in clinically-healthy and diarrheic suckling calves in this research is a concern for public health. Further epidemiological work on role of stx1 gene in diarrhea of suckling calves in Sistan and Baluchistan province is recommended.

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