Distribution of virulence associated genes in isolatedEscherichia coli from avian colibacillosis

BACKGROUND: Colibacillosis is one of the most prevalent diseases in the world that causes multimillion-dollar annual losses. OBJECTIVES: In order to evaluate molecular epidemiology of some virulence associated factors in Escherichia coli, isolated from poultry, the presence of iut A, iss, hly F, omp T, iro N, afa, sfa (S)and pap G (II) were investigated by multiplex PCR assay. METHODS: Two hundred thirty four Escherichia coli isolated 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 was performed using |c 2 test. the p-value was |£|0.05. RESULTS: Among 234 E. coli strains associated with colibacillosis and 54 AFEC strains, 85% of isolates were positive for at least one of the virulence gene. The three most prevalent genes in E. coli isolated from 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 isolates harbored sfa (s) and afa genes. Several combination patterns of virulence genes were detected. Combination of hly F, omp T (70.8%) was the most prevalent pattern. CONCLUSIONS: the prevalence of iss, hly F, omp T, iro N genes in APEC isolates was significantly more than AFEC strains and probably these genes play an important role in the pathogenesis of APEC strains.

Keywords:

Avian pathogenic Escherichia coli , multiplex PCR , virulent factors