Diagnosis Of Turkey Fowl Cholera And Serotyp Identification Of Pasteurella Multocida

Avian pasteurellosis, also known as fowl cholera, is an acute septic infectious disease caused by pasteurella multocida, which can infect all poultry, mostly lethally. It is more common in poultry more than 16-weeks-old, while most common and diseas especialty adult turkeys. This disease is prevalent around the world, which is one of the most important bacterial infectious diseases seriously harming the poultry industry. Pathogens carriers or infected poultry are an important source of infection. This disease is of sudden onset and high fatality, and may cause acute and hemorrhagic septicemia for poultry and wild birds, which causes a great number of economic loss for poultry industry.5 turkeys died in a Changchun zoo in August 2014 after attack, where 2 died in the night, while the rest 3 turkeys had clinical manifestations, including depressed spirit, loose feather had, high body temperature(43.5 ℃), green loose feces, and cramped breathing, etc. Clinical autopsy revealed hepatomegaly, grey dotted hemorrhage on the surface, dotted epicardial hemorrhage, and duodenal catarrhal hemorrhagic inflammation. According to clinical symptoms and pathological changes, the cause of the disease is primarily suspected as turkey fowl cholera. To further verify the diagnosis, an in-depth systemic research was carried out in this study to explore the pathogenesis and pathogen characteristics from the angle of pathology and etiology. The methods concluded histologic examination, bacteriology examination, animal regression test and PCR. And the concrete research content was as follows:1. Pathological diagnosis of turkey fowl choleraPathological materials were collected from dead turkeys and made into pathological sections. Myocardial fibers were fractured, and part of the nucleus were disappeared in the heart; red blood cells were visible in myocardial fiber clearance; interstitial infiltration of inflammatory cells and white blood cells were observel; hepatic veins were congested and expanded, with a large number of red blood cells filled in lumen and sinus; necrosis was found in part of liver cells, with dissolved nucleus and vacuolation; there was remarkable hyperemia and hemorrhage in lamina propria of small intestinal mucosa; villous stroma was invaded by RBC and WBC; and the intestinal villus cells fell off;) catarrhal hemorrhagic enteritis was showed; there was obvious pulmonary congestion, together with a large amount of red blood cells and white blood cells in the enlarged septum.2 Isolation and identification of pasteurella multocidaHeart, blood and liver tissues were taken from dead turkeys. Pathogens were separated and cultured in TSA medium. The isolated strains were identified with staining, biochemical and microbial identification, as well as animal regression test. Red short bacillus in gram staining and dipolar dense stained bacillus in methylene blue staining consisted with biochemical characteristics of pasteurella multocida to. Microbial identification system showed the isolated strains were closest with the pasteurella multocida in fatty acid content. Young bird regression test showed LD50 22 CFU. DNA of isolated strains were further taken for identification of Kmt and 16 s rRNA, and the results showed amplified Kmt genes, and the isolated strain had more than 98% of homology with poultry-derived pasteurella multocida including C48-11. After 16 s rRNA sequencing, comparative analysis also showed the isolated strains had as high as 99% homology with pasteurella multocida ATCC 43137. These confirmed the isolated strains were pasteurella multocida from the molecular level. PCR was used for capsular typing and lipopolysaccharide serotyping. Capsular typing showed this isolated strain was type A pasteurella multocida, while lipopolysaccharide serotyping confirmed it as type L3. Thus it could be seen that the serotype of isolated pasteurella multocida was 3:A or 4:A, which is the major popular serotype of fowl cholera in China.Using doing sensivitu test to screen druges strains had a very high sensitivity to cefotaxime sodium, ceftriaxone, aztreonam, Pipemidic acid,Selection of cefotaxime and ceftriaxone injection, combined with strict disinfection, agaist the occurrence and spread of the disease.