Investigation Of Toxin Gene, Adhesin, O Serotype And Drug Resistant Of Cattle Escherichia Coli

Escherichia coli, the member of Escherichia coli, Escherichia, was found by Escherich in 1885. It has been long regarded as a kind of normal microflora in intestinal tract, which can not cause diseases. By the middle of the 20 th.century, it was found that some serotypes of E. coli has certain pathogenesis in animals and people, especially in young animals and babies. It can cause diseases including severe diarrhea and sepsis. Both in developed countries or developing countries, the diarrhea caused by Escherichia coli remains a serious threat to human’s health, causing bradygenesis for ill animal, depressing production performance, and even death. All of these will lead to serious damage to the breeding industry.This research collected diarrheal faeces from 108 heads of calves within the different cattle camps in different regions of Heilongjiang province. Via co-cultivation of macconkey nutrition agar and EMB medium and using 16 S r RNA universal primers for PCR detection, we evaluated the E. coli by sequencing comparison, combining the traditional biochemical test evaluation methods, then, we separated and identified 88 strains of E. coli, and made the detections of Toxin genes( Eae+Stx1+Stx2+bfp A+LT+Sta+Stb+), Stick genes(k88+k99+F17+F6+F18+F41+), Type O blood serum screening, drug resistance analysis.Through these results, we can know that there are 38 strains of E. coli can be detected the toxin genes with the rate of 43.18%. And they can be divided as 11 types of toxins. The main types are eae, sta, stb and bfp A4 with the amount of 13, 8, 15 and 16 strains respectively. On the basis of genotype, the E. coli can be divided into five types: ETEC, atypical EPEC, typical EPEC, ETEC/EPEC and ETEC/EHEC. Among these 15 strains of ETEC were detected as 39.47% of the toxin gene positive strains. A total of 60 strains can express one or more adhesion with the detection rate of 68.18%. Through this research we detected 11 kinds of adhesion types, which are given priority to with F18 and K88 adhesion element types which account for 53.33% and 20% respectively in positive adhesion strains. And the serum agglutination test is used for 19 kinds of common pathogenic serotype, then we checked out 14 kinds of serotype with the superiority serotypes of O2, O125 and O128. Through the medicine sensitive experiment we can know that the isolated strains were multiple antimicrobial resistance to three or more antibiotics. Among the results, the isolated strains are highly resistant to the rifampicin(96.6%), amoxicillin(97.7%) and ampicillin(97.7%), and are resistant to the gentamicin(30.7%), ofloxacin(30.7%), ciprofloxacin(33.0%) and nalidixic acid(37.5%).This research shows that in Heilongjiang province there the types of pathogenic E.coli. are diversified which are given priority to ETEC, EPEC. And the serotype are distributing scattered and are highly resistant.