Molecular Detection of the Virulence Genes in Escherichia coli Isolated from Healthy and Diarrheic Calves in Southern Iraq

Aim: To investigate the stx1, stx2, hly, cnf2, sfa/foc, afaI, papC, and afaC virulence-associated genes of pathogenic Escherichia coli, isolated from diarrheic and non-diarrheic calves.

Materials and Methods: The genes to be investigated were first isolated from the stool samples obtained from 150 diarrheic and non-diarrheic calves, between the ages of one day and six months, during the period 2016 to 2017. Rectal swabs were aseptically and randomly collected from several herds, from different regions in the province of Basra.

Results of Research: The polymerase chain reaction (PCR) results showed that pathogenic E. coli were detected in a total of 34 out of 41 (82.9%) distributed as 23 out of 26 (88.5%) and 11 out of 15 (73.3%) of the diarrheagenic and non-diarrheagenic calves, respectively. The results also showed that stx1, hlyA, and stx2genes showed a higher incidence of distribution in both diarrheagenic and non-diarrheagenic calves, in a percentage rate of 69.6%, 65.2%, 56.5% and 63.6%, 63.6%, 45.5%, respectively. Moreover, eight different virulence gene profiles were established in the present study. Most of the isolates analyzed had at least two or three gene arrangements and only four isolates were seen in a combination of four genes stx1, stx2, hlyA, and afaI.

Conclusion: It is concluded that E. coli isolates from healthy and diarrheic calves that carried various virulence genes, of which the most frequent were stx1, stx2, and hlyA. A high percentage of these isolates are found in both diarrheic and non-diarrheic calves.