Isolation,Identification,and Analysis Of Related Genes Of HPI Pathogenicity Island Of Escherichia Coli In Calves Diarrhea Disease In Northeast Of China

Calf diarrhea colibacillosis, a digestive disease, is caused by pathogenic Escherichia coli in newborn calve that is one of the most bacterial pathogens causing calf diarrhea. E. coli has many kinds of virulence factors, and their pathogenicity may result from the cooperation of many virulence factors. In recent years, the race of morbidity and mortality of calf diarrhea has been increasing, and their drug resistance are increasing. Pathogenetic E. Coli as an important zoonotic pathogens has seriously endangered human health.In order to investigate the calf diarrhea pathogens, a case study of 153 rectal swab samples from suspected diarrhea calf in northeastern China was conducted from August 2013 to December 2013. Then pathogens were isolated and physicochemical properties, 16 s rDNA and O factor serotype were determined. Moreover, carrying situation of irp2、irp3、irp5、irp8、asn_tRNA_intB、 fyuA、ybtA genes have also been detected.A total of 74 E. coli, 3 Klebsiella pneumoniaeisolates, 7 Enterobacteriaceae(species is not identified), 1 Escherichia, 1 enterobacter sakazakii were isolated using their culture characteristics, physical and chemical identification, and molecular biology.In the present study, a total of 8 single serotypes, namely O2, O9, O14, O15, O36, O78, O101 and O137, were identified including two mixed serotypes(O14-O15 and O14-O137). Among them, O14, O36, O14-O15 and O14-O137 were the predominant serotypes. All of the pathogenetic E. coli was infection, and 28 of them had high pathogenicity.In the present study, a total of 8 single serotypes, namely O2, O9, O14, O15, O36, O78, O101 and O137, were identified, with two mixed serotypes(O14-O15 and O14-O137). Among them, O14, O36, O14-O15 and O14-O137 were the predominant serotypes. Pathogenetic E. coli is responsible for 83% of all E. coli infection, and 28 of them had high pathogenicity.At last, IHP pathogenicity island of E. coli identified in this study, had also been tested. The positive rate of irp2 was 74%(55/74). Moreover, the positive rates of fyuA, irp3, irp5, irp8, asn-tRNA-intB and ybtA was 32%(18/55), 23%(13/55), 12%(7/55), 27%(15/55), 10%(6/55) and 23%(13/55), were respectively.In conclusion, the present study preliminarily explores the distribution of serotype and virulence factor of E. coli in cattle in northeastern China, and could also provide data for clinically reasonal administration of drugs and, prevention and control of colibacillosis in cattle.