Abstract
The aim of the current study was to characterize E. coli isolates belonging to several serotypes in samples from different animal sources. The genetic diversity among the isolates was evaluated by multiplex PCR. Out of 30 suspected isolated E. coli which were identified microscopically, culturally and biochemically examined by VITEK2 and serologically identified there were 8 isolates showing low discrimination for E. coli and were non-typeable while 22 isolates positive, showing excellent level of identification for E. coli and were identified serologically. Thirteen different serogroups were identified, O26:H11, O91:H21, O78, O111:H2, O125:H21, O146:H21, O1:H7, O44:H18, O55:H7, O119:H6, O121:H7, O128:H2 and O159. Findings of multiplex PCR of virulence genes showed that the eaeA gene was successfully amplified in O26:H11; stx1 gene was successfully amplified in O26:H11, O55:H7, O91:H21, O111:H2, O119:H6, O128:H2 and O146:H21 serogroups but stx2 gene was successfully amplified in O1:H7, O26:H11, O78, O91:H21, O111:H2, O119:H6 and O125:H21. O91:H21, O111:H2 and O119:H6 serogroups carried both (stx1 and stx 2) genes, O26:H11 serogroup carried (stx 1, stx 2 and eae) genes and O44:H18, O121:H7 and O159 serogroups were negative for these genes. Findings of multiplex PCR of β-lactamase antimicrobial resistance genes showed that blaOXA gene was successfully amplified in O26:H11 only; blaCTX-M1 gene was successfully amplified in O78 and O121:H7 serogroups but blaTEM gene was successfully amplified in O26:H11, O91:H21, O111:H2 and O125: H21. O26:H11 serogroup carried both (blaOXA and blaTEM) genes and O1: H7, O44:H18, O55:H7, O119:H6, O128:H2, O146:H21 and O159 serogroups were negative for (blaOXA, blaCTX-M and blaTEM) genes. In conclusion, animals and animal products could be a significant reservoir of diverse E. coli virulence and antimicrobial resistance genes which is potentially hazardous to public health.

Key words: E. coli, VITEK2, serotyping, PCR, virulence genes, β-lactamase resistance genes.