Isolation And Characterization Of The Pathogenic E.Coli And Prevention And Control Of Avian Colibacillosis In Nanyang District

Colibacillosis is an important disease,which harms poultry industry acutely.By statistics,cases of colibacillosis are the first disease occur in poultry yards of NanYang city.Prevention and cure to the pathogen can not be easy,because of diverse serotype and increasing drug resistance.Therefore,it is necessary to isolate the avian pathogenic E.coli from septicemic poultry in NanYang city,and examine the antimicrobial resistance,also the distribution of virulence associated genes,to find out the regularity of invasion and tomake out scientific possible measure of prevention and cure.E.coli strains were isolated from sick chicken in a number of poultry yards in NanYang city,and then they were cultured,purified and tested under microscope by common method,and the result of physiology and biochemistry test twenty-nine strains with culturing were morphological characters were isolated.Serotype appreciation of 29 strains were made and classified as 3 serotypes.The main serotypes were as follows:4 strains of O1,3 strains of O2,7 strains O78,which were presumed the dominant serotype,and 14 strains of were serotyped occupied 48.3%of total isolates.29 isolated strains were used to challenge young chicken.Both clinical symptome and pathological changes of dissection fitted typical characters of the pathogen.The strains of high pathogenicity occupied 44.8%,the middle ones did 31% and the low ones did 24.2%.Kieby-Bauer paper method was adopted to make susceptibility test to 29 isolated strains with 22 kinds of susceptibility test paper slip.The results of susceptibility tests showed that the medicine resistance of the isolated strains was rather strong,the bacteria only showed high sensitivity to Ceftriaxone sodium,Neomycin sulfate, amikacin and spectinomycin.The isolates were investigated for the presence of 6 virulence associated genes described for avian pathogenic E.coli.Three genes were significantly distributed among high pathogenicity APEC strains,including iucD(76.92%),iss(92.31%),and irp2(61.54%).These findings provide novel insights into the presence and distribution of virulence-associated genes in avian pathogenic E.coli field strains.In this study,self-made extinguishable vaccine of E.coli selected from the experimental farm was producted,with other protective method to protect sensitive chicken block,resulting a significant decreasing sickness rate.The ideal effects were also made in infected flocks using the vaccine with sensitivity medicine and Chinese herb medicine JunXiaoSan.Moreover,the synthesized methods of prevention and cure should be improved to prevent the pathogen,such as management of feeding and degermation.