The Study On Biological Characteristic And Pathogensis Of Different Shigella

Shigellosis of chicken is a new infectious disease,which found in recent years. The disease is an acute infections disease caused by Shigella,which can give rise to different species,different age of chicken diarrhea and death of chickling. The current study results show that Shigellosis of chicken was widespread and harmful. At present,the study on the pathogenicity of the chicken to be infected with s.boydii and s.dysenteriae Has done a little.but there has not study on pathogenicity of the chicken to be infected with S.flexneri Because of the spread of Shigellosis,the poultry industry of China has tremendous economic losses.Shigella may cause cross-infection between human and poultry,which led to serious security risks for human public health. Therefore,the study of Shigellosis of chicken not only has important veterinary health significance,but also has great medical public health significance.the different shigella which is S.boydii S.dysentery and S.flexneri.as research material of the project was isolated from chicken, identified and conserved by the laboratory. The study of biology characteristics and pathogenicity was carried, .The results are as follows:First,the study to carry on bacteria appearance,cultivating characteristics and biochemical characteristics in addition to Animal testing In ord to understand that the biology characteristics of different of shigella. finnal indicated that fourteen bacteria belong to Shigellae; Serological typing test were performed that these Strain have differences in species and type.The results revealed that eight strains identified for S. flexneri, Three strains identified for S.boydii, three strains identified for S.dysenteriae infection. The animal experiment suggests that the fourteen Shigella is Pathogenic, but the Virulence is different. The strain from sanmenxia is virulent, morbidity and mortality is 100%. The sensitivity tests to drugs show that most shigellae from chicken sensitive to ampicillin/sulbactam and amikacin, and Serious resistant for other drugs,the sensitiveness is different in different Region for the Shigellae from chicken. This study provide a scientific basis, Shigella bacteria on chicken Diagnosis and treatment of disease and is of great significance and value.Second,we select six virulent strain from the fourteen shigella which is SMX09-2 strains、ZK09-2 strains、JZ09-2 strains、SQ09-2 strains、XZ09-2 strains、ZZ09-2 strains. three-days-old Hy-Line chicks that non-immunity received oral administration and intraperitoneal injection With seven different doses of every strains. we observation on the lesions of the experimental animal after the chicken death and the LD50 of shigella was calculate in 7 days in chicken adopt the Bliss with the SPSS 10.0. and conventional paraffin sectioning was adopt to conduct the tissue after infected with Chicken Shigella and Pathological changes were observed by HE This study indicated the pathological character of diseased chicken The main clinical manifestations included depressed of ill chicken spirit,diarrhea,stool with the blood,Pathoanatomical results showed that mainly in the alimentary canal. Ileum bleeding,bowel wall thinningzed.The Pathological changes indicate that cardiac muscle fibers swelling、fracture. hepatic sinusoidal cells enlarge, Liver was congested, Liver cell had fatty, degeneration or vacuole degeneration. Necrosis and desquamate of intestinal mucosa, hemorrhage,Desquamate and desquamate, inflammatory infiltrate. blood capollary of submucosa had hemorrhage. many lymphocytes necrosised,the cell nucleuses soluted. The virulence with oral administration lower than intraperitioneal injection.the SMX09-1 strains is virulent strain than the other strain.The intraperitoneal injection LD 50 of SMX09-1 in Chicken was 5.47×105,ZK09-2 strains has a poor virulent, the death Rate is lower 50% all the experimental group.the other four strains has strong virulence to chicken,the LD 50 in SQ09-1 strains,XZ09-2 strains,JZ09-2 strains,ZZ09-2 strains were 3.52×10~9,5.73×10~6,1.6×10~8,4.439×10~9 respectly.The virulence with oral administration lower than intraperitoneal injection.