Genotyping of virulence factors in avian pathogenic E. coli by multiplex PCR.

Colibacillosis caused by pathogenic E. coli strains (Avian Pathogenic Escherichia coli) is one of the main causes of economic losses in poultry breeding industry worldwide. This acute infection of birds may be clinically localized or systemic, several of the lesions in visceral organs are observed. Virulence factors in the E. coli genome, described in various studies, have not clarified prevalence of APEC strains, and their importance in the infection pathogenesis is still unknown. Conducted surveys indicate that the presence of virulence genes in E. coli isolates is the starting point of differentiation and characterization of pathogenic E. coli to those intestinal and opportunistic. A total of 158 E. coli strains were examined for the presence of eight virulence genes: iss, tsh, papC, vat, cvaA/B, iucD, astA, irp2, by means of molecular biology technique PCR-multiplex (Ewers et al. 2004). This study identified significant differences of virulence factors among strains isolated from lesions, compared to those from apparently healthy subjects. iss, responsible for increased serum survival in the E. coli bacteria, was the virulence factor with the highest percentage of detection (42.40%). Virulence genes frequency is considered to be an important indicator of the virulence of E. coli strains. Thus the lack of virulence factors in APEC strains resulted in 27.18%, while in AFEC strains resulted in 61.81%. These data obtained from genetic characterization of avian E. coli strains constitute the first report in Albania for colibacillosis infection outbreak in poultry flocks. The presence, appearance and distribution of virulence genes in poultry flocks provide basic information for the control and eradication of the colibacillosis infection.