Phylogenetic clustering and virulence-associated genes of avian pathogenic Escherichia coli in some areas of eastern China

Sixty-six strains of avian pathogenic Escherichia coli( APEC) were isolated from dead chickens in some poultry farms of eastern China. PCR methods were used to perform phylogenetic clustering and to detect 9 virulence-associated genes. The APEC isolates distribute in the different phylogenetic groups,including groups A( 22 /66),B1( 21 /66),B2( 9 /66) and D( 14 /66). The results of virulence genes showed that the distribution percentages of aatA,aatB,ibeA,vat,tsh,ireA,vgrG,clpV1 and ybtX were 59. 1%,13. 6%,7. 58%, 37. 9%,36. 4%,25. 8%,6. 06%,21. 2% and 42. 4%,respectively. Six genes including aatA,tsh,vat,ybtX,ireA and clpV1 were widely distributed among different groups,while ibeA only appeared in group B2. This study is helpful to further understand the molecular ep- idemiology of avian colibacillosis and provides the basis for the prevention and control of the disease.