Isolation, Identification And Biological Characterization Of Bacterial Pathogen In Outbreak Of Swie High Fever Disease

Swine "high fever disease" was caused by multiple infection with kinds of pathogens, secondary infection of bacteria usually exacerbates the severity of the disease. So, isolation and identification of bacteria from pigs with"high fever disease"will are favorable for developing effective measure of prevention and control for "high fever disease".A multiplex PCR technology was developed for PCR detection of HPS,Pm,APP with sensitivity of the minimum DNA amount of 60pg,120pg and 50pg. Results demostrated that the multiplex PCR was highly specific, sensitive, and precise in detecting HPS,Pm,APP from infected animals.146 tissue samples of infected pigs were collected from 10 different regions including Feidong, Feixi, Huaibei, Tongcheng, Fuyang, Suzhou, Luan, Lujiang, Xuancheng and Shucheng in Anhui Province. 67 strains of bacteria were isolated with positive percentage of 45.89%, and 20 SS strains,12 HPS strains,16 Pm strains and 2 APP strains were identified with the percentage of 29.85%;17.91%;23.88% and 2.98%. It is sugggested that bacterial secondary infection or mixed infection are one of the important inducement of swine "high fever disease" in Anhui Province. Out of 67 bactria isolates, 12 Pm strains were further identified as serotype A, which stands for the predominant serotype in Anhui; 5 of 20 SS isolate were designated as serotype 2 by using the PCR specific amplication and the PCR-RFLP was developed for further identification of the 12 HPS strains and 5 different genotype. 2 strains of APP belong to serotype 1 due to the biochemistry test. The results confirmed that the infected pigs with"high fever disease"experienced diverse bacteric agents with different serotypes. Results of drug sensitive test showed the isolated strains were resistant to available drugs, but all of isolates were sensitive to Cefotaxime,Amoxicillin,Ciprofloxacin and Chloromycetin.The nucleotide sequences of the tbpA in the HPS strains were amplified and sequenced, and phylogenetic analysis of tbpA gene was consistent with RFLP assay, the isolates of HPS share the homology of Animal regression test and RFLP demostrated that tbpA gene of HPS isolates was closely related with the virulence of HPS.Above all, isolation and identification of bacterial causative agents, predominant serotype, drug susceptibility test lay the foundation for making effective measures for prevention and control of swine "high fever disease".