Author/Authors :
Dastmalchi Saei, H Department of Microbiology - Faculty of Veterinary Medicine and Department of Cellular and Molecular Biotechnology - Institute of Biotechnology - Urmia University,Urmia , Ayremlou, N Graduated from Faculty of Veterinary Medicine - Urmia University, Urmia
Abstract :
Background and Objectives: Shiga toxin-producing Escherichia coli (STEC) have emerged as human pathogens and
contamination of foods of animal origin has been a major public health concern. The aim of the present study was to
determine the dissemination of STEC in healthy and diarrheic calves in Urmia region which is located in West Azerbaijan
province, Iran.
Materials and Methods: In the current study, a total of 124 Escherichia coli isolates from clinically healthy (n = 73)
and diarrheic calves (51) belonging to 6 different farms located in West Azerbaijan province, Iran, were screened by the
polymerase chain reaction (PCR) assay for the presence of virulence genes characteristic for STEC, that is, Shiga-toxin
producing gene(s) (stx1, stx2), intimin (eaeA) and enterohemolysin (hlyA).
Results: STEC isolates were recovered from 21.92% (16/73) in healthy calves, and 19.6% (10/51) in diarrheic calves.
Overall, PCR results showed that 6 (23.1%) isolates carried stx1 gene, 7 (26.92%) possessed stx2 gene while 13 isolates
(50%) gave positive amplicon both for stx1 and stx2 genes. All stx positive isolates were assayed further to detect eaeA
and hlyA sequences. Seven out of the 26 (26.92%) Shiga toxin gene positive isolates were positive for the eaeA gene, and
15 (57.69%) were positive for the hlyA gene. Both virulence genes (eaeA and hlyA) in the same isolate were observed in 5
(19.23%) of the stx+ isolates. In total, diverse virulence gene profiles were detected, from which isolates with the genetic
profile stx1 stx2 hlyA was the most prevalent. In addition, eaeA gene was more evident in isolates from diarrheic calves than
in healthy calves.
Conclusion: There was no significant difference in detecting STEC isolates between healthy and diarrheic calves. It seems
that calves to be the reservoir of STEC within the herds and calf management may represent specific control points for
reducing STEC spread within dairy units.
Keywords :
Shiga toxin , E. coli , calves , Iran
