Prevalence,phenotypes and virulence factors characteristics of Escherichia coli O157 strains in Yuxi city

Objectives:To determine and analyse the carrier rate and characteristics of Escherichia coli O157 in milk cattle, pigs, chickens and patients who suffered from diarrhea; and provide scientific information for the prevention and treatment of infections of E. coli O157 as well as establishing the check techniques of E.coli O157. Methods:Surveillance spots were set up at one biggest milk cattle feedlot, one pigs slaughterhouse, two chickens markets and the laboratory department of Yuxi city hospital in Yuxi city, to collect feces of cattle, pigs, chickens, patients with diarrhea, the numbers of specimen were 70,250,350 and 400 respectively, to isolate and culture for E.coli O157 with immunomagnetic separation and immunochromatography technology were carried out. The purified strains were cultured and examined by 3 differential media as well as France biomerieux AMS VITEK 32 GNI+s or identification system for Enterobacteriaceae API 20E strips, serological tests, polymerase chain reactions(PCR), phage type. Results: 11 strains of E.coli O157 were separated from 70 cattle feces, 250 pigs feces and 400 patients feces. Obtained 4 strains of E.coli O157∶H7, 6 strains E.coli O157∶Hund and 1 strain of E.coli O157∶H NM . The overall carrier rate was 1.5%. The Carrier rates of cattle, pigs, chickens and patients with diarrhea were 1.4%, 2.0%, 0 and 1.2% respectively. Understanded the morphologies, biochemistries, serologies, virulence factors, phage types, tellurite resistance of 11 strains of E.coli O157.Conclusions:Multiple strains of E.coli O157 exist in a single crowd or a single flock of animals and a single animal or patient shed two strains or more simultaneously. The phenotypes and virulence factors characteristics of E.coli O157 strains exist difference to a certain extent. Genetic fingerprinting techniques can define and identify further the differences among the strains.