Abstract: The purpose of this study was to determine the presence of selected virulence genes in Avian Pathogenic Escherichia coli (APEC). We examined 12 APEC isolates which belonged to the most common serotypes in Iran. All 12 isolates were tested for the presence of stx1, stx2, eae, espB and hly genes by multiplex polymerase chain reaction in two protocols. In the first protocol the isolates were tested with EC and with hly primers,
and in the second protocol the isolates were examined with eae, stx1, stx2 and espB primers. Seventy five percent (9) of the isolates carried only stx2 gene sequence and just one isolate had both stx1 and stx2 genes. Furthermore, 2 isolates (16.66 %) possessed eae sequence and 3 isolates carried espB (25%). The hly gene was not detected in any of the isolates.
The findings of this study indicated that the Stx2 may be widespread among APEC in Iran. J.Vet.Res. 62,2:37-42,2007.