distribution of virulence associated genes in isolated escherichia coli from avian colibacillosis

background: colibacillosis is one of the most prevalentdiseases in the world that causes multimillion-dollar annuallosses. objectives: in order to evaluate molecular epidemiologyof some virulence associated factors in escherichia coli,isolated from poultry, the presence of iut a, iss, hly f, omp t, iron, afa, sfa (s)and pap g (ii) were investigated by multiplex pcrassay. methods: two hundred thirty four escherichia coliisolated from avian colibacillosis (apec) and fifty four fecal e.coli isolates from the feces of apparently healthy birds (afec)were investigated for presence of some virulence associatedgenes by two panel of multiplex pcr. statistical analysis wasperformed using |c2 test. the p-value was |£|0.05. results:among 234 e. coli strains associated with colibacillosis and 54afec strains, 85% of isolates were positive for at least one of thevirulence gene. the three most prevalent genes in e. coli isolatedfrom colibacillosis were hly f (77.3%), omp t(73%) and iss(68.2%). iut a, iro nand pap g (ii) were detected in 157 (67.4%),152 (65.2%) and 41(17.6%) respectively. none of isolatesharbored sfa (s) and afa genes. several combination patterns ofvirulence genes were detected. combination of hly f, omp t(70.8%) was the most prevalent pattern. conclusions: theprevalence of iss, hly f, omp t, iro n genes in apec isolates wassignificantly more than afec strains and probably these genesplay an important role in the pathogenesis of apec strains.