| In recent years, with the rapid development of the sheep industry, intensification increased gradually. However, the potential problems are created, increasing the frequency of occurrence and spread of disease, disease prevention and control system is imperfect,feeding and management lags behind, emerging new diseases, disease-causing bacteria is always difficult to be effectively controlled.2014, infectious respiratory diseases appeared in many intensive sheep farms of Ningyang, Wenshang, Laiwu and Tengzhou. The morbidity and mortality of acute diseases were very high, pneumonia lesions severe, making it difficult to determine their pathogens.To better ascertain their virulence factors, the study consists of multiple intensive sheep farm s epidemiological investigation,collection of sick animals lungs, isolation, identification and phylogenetic analysis of important pathogen.The study is divided into three parts:The first part Epidemiological survey in the intensive sheep farmsEpidemiological survey in the intensive sheep farms indicates that prevalence and mortality of infectious diseases in intensive sheep farms are higher than common diseases and parasitic diseases, infectious morbidity and mortality rates were 21.5 % and 4.5%, parasitic disease morbidity and mortality rates were 17.0% and 2.5%, while the average morbidity and mortality rates were 10.0% and 1.5%. Sheep farms poor feeding management and inadequate security system are important causes of increased prevalence of infectious diseases,indicating the formation of safety prevention system and good feeding and management conditions are very important in the production practice.The second part Isolation and identification of intensive sheep farms major pathogensCompound 80, five kinds of pathogens were isolated from 45 copies clinical samples.Streptococcus, Staphylococcus, Klebsiella pneumoniae, Escherichia coli and Mannheimia haemolytwa were found mainly by pathogens Isolation, staining, biochemical tests measuring. Animal challenge trial found that each test group of mice had difficulty breathing,reduced activity, coat against the legislation, reduced feed intake and other symptoms during12-24 hours post challenge. Among them, mice of Mannheimia haemolytica group began and all died after 3 days post challenge, mice of Klebsiella pneumoniae group began and died one after another from the second day post challenge, mice of Escherichia coli group and the control group did not die. Autopsy after the death of the two groups of mice showed severe lung disease. Mannheimia haemolytica, Klebsiella pneumoniae and Staphylococcus group mice mortality rates were 100%, 80% and 60% respectively, and the corresponding pathogenic bacteria are isolated in vivo of death mice. The test results Using 15 kinds of standard bacteria sensitive drugs for the sensitivity test of several bacteria with disk diffusion method showed that the majority of bacteria were strong sensitivity to ofloxacin,nitrofurantoin and cephalosporins. Mannheimia haemolytica was stronger sensitivity to cephalosporins, quinolones and other antibiotics nitrofurantoin than neomycin, kanamycin,gentamicin and other aminoglycoside antibiotics which produced some resistance. Klebsiella pneumoniae, streptococcus, E. coli susceptibility test results showed consistent strong,varying degrees of sensitivity to nitrofurantoin and gentamicin and strong resistance to ephalosporins and quinolones. Staphylococcus aureus was sensitive to most drugs. We must pay attention to the effectiveness and efficiency combine when we use drugs in clinical practiceThe third part the determination of pneumonia pathogens 16 SrRNA gene sequences and phylogenetic analysisThis section showed that Mannheimia haemolytica lead to pneumonia pathogens.Homology analysis by DNAStar with the PA standard strains of bacteria in GenBank showed that homology of Mannheimia haemolytica isolated with the United States, Xinjiang,Guangdong and other places homologous strains were above 99.5%, indicating that between regions and different animal species Mannheimia haemolytica, 16 S sequence mutations less,which facilitates the use of large-scale sheep farm molecular diagnostic techniques to identify them, to take a scientific means of prevention and treatment of Hemolysis mansoni Bacillus disease... |
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