| In recent years, the impact of chicken colibacillosis for the poultry industry is getting worse and worse with the development of the poultry industry. The disease often happens together with many other bacterial and viral diseases and having the characters of complicated antigens, diverse serotypes, clinical symptoms and varied pathological changes. Antimicrobial agents are used unreasonably, resulting in the continual emergence of drug-resistant strains of E. coli, and creating a vicious cycle. The prevalence of E. coli disease in Jinan is still relatively vague. Therefore, it is necessary to carry out this study due to the lack of systematic study of drug resistance in pathogenic strains In this thesis, at first, epidemiological investigations of Jinan chicken industry was conducted and present conditions and hazards of the chicken E. coli epidemic were studied. On this basis, the research on the isolation and identification of pathogenic E. coli strains, determination its main serotypes, and conducting the drug sensitive test, were carried out and selecting effective clinical drugs for the clinic to find the most appropriate treatment. It is hoped that a scientific basis for effective control of n chicken colibacillosis in Jinan can be provided and some favors can be done for the well development of poultry industry through this experiment. This paper is divided into three parts:1. Epidemiological investigation A detailed understanding has been obtained with incidence of E. coli disease in chickens, popular features, etiology, pathogenesis Day age, etc. through the investigation of the prevalence of E. coli disease in recent years from the dozens of chicken farm and culturist in the 10 counties of Jinan zone. The factors of the diseases is very complicated. The incidence rate was 24.14%, the mortality rate was 43.12 %, and there was an increasing trend. The age of 15-35 days are dominate, accounting for 50-60 % of the total incidence of E. coli disease. Egg layers tend to start disease in time of before and after producing eggs as well as the summit period of laying eggs and less in incubation times. Local E. coli disease occurs with marked seasonal characters and closely with the local farming technology. The incidence of E. coli disease in the cold of winter(December to the next January) and hot and rainy wet season(July to August) and the temperature varied season(April to May) are in main proportion, accounting for the total of about 80 %.2. Separation and Identification of pathogeny and drug sensitive test The test extracts 41 fatal colibacillosis out of 50 types of the chicken and broiler patient compounds with the separation rate of 82 % in Jinan using conventional bacterial isolation, identification methods. 8 serotypes of O78, O1, O11, O88, O18, O5, O26, O111 are separated and identified by E. coli O antigen. O78, O1, O11 serotypes are dominate accounting for 75% of typing strains, and O78 serotype is the dominant serotype and for 45 %. The drug sensitive test of bacteria shows that amikacin, cefotaxime, cefazolin and florfenicol are high sensitive, Ciprofloxacin, gentamicin, kanamycin, ofloxacin and norfloxacin are moderately sensitive, and streptomycin, neomycin, chloramphenicol, tylosin, erythromycin, lincomycin, ampicillin, amoxicillin, tetracycline and doxycycline are less sensitive.3. Prevention and control of chicken E. coli disease in Jinan Amikacin, florfenicol, cefotaxime, cefazolin being selected by drug sensitivity level were used for the the diagnosed diseased chickens in field immunity test. The cure rate was 98.9 % for amikacin, 98.8 % for florfenicol, 98.9 % for cefotaxime and 98.9 % for cefazolin. The results show that high sensitivity of these four drugs have a good influence on the prevention and control of E. coli disease. |
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