[Isolation of avian Escherichia coli and PCR detection of their F1 and HPI genes]

Abstract

To further investigate into the prevalence of F1 fimbriae and high pathogenicity island (HPI) in avian Escherichia coli, a total of 69 bacteria isolates (29 from geese and 40 from chickens) were obtained from deceased poultry and characterized to be Escherichia coli by gram staining, culture characterizing and bio-chemical testing. Two sets of primers were designed or analyzed with DNAStar software based on the F1 and HPI sequences that deposited in GenBank and synthesized by Sangon Biological Engineering Technology and Service Co. Ltd. (Shanghai, P. R. China). All the primers were tested for their specificities by using reference E. coli strains, and it is confirmed that the PCR using primers F1-F and F1-R could identify F1+ E. coli, as well as the PCR using primers irp-F and irp-R could identify HPI+ E. coli. All the isolates were submitted to PCR detection, and the data shows 46 isolates (66.7%) were F1-positive, 10 isolates (14.5%) were F1+ HPI-positive and 2 isolates (20.0%) were HPI-positive. Furthermore analysis indicated that the prevalence of F1 and HPI have no different between the isolates from geese and chickens, and no different among the isolates from different tissue, such as liver, lung and duodenum. In addition, all the 69 E. coli isolates serological typed, and the results show that the isolates from geese were belonged to O26 (25.0%), O78 (12.5%), O18 (12.5%) and O117 (12.5%), while E coli from chickens were fell into O109 (37.5%), O24 (18.75%), O18 (12.5%), O139 (12.5%) and O78 (6.25%). Seven kinds of antibiotics were tested on 11 isolates, and it revealed that most isolates were sensitive to cefazolin, nitrofurantoin and gentamycin, while resistant to lincomycin, tetracycline and polymycin B.