PRRSV阳性猪源肺炎克雷伯菌的分离鉴定及特性分析OA北大核心CSTPCD

The aim of this study was to investigate the bacterial pathogens and their biological characteristics of secondary infection after clinical infection with porcine reproductive and respi-ratory syndrome virus(PRRSV),and to provide a research basis for the effective prevention and control of PRRSV secondary bacterial infection.The pleural effusion of dead piglets infected with PRRSV was asep-tically collected for bacterial isolation and purification.The isolated bacteria were subjected to morphological identification,molecular biological identification,drug sensitivity test,drug resis-tance gene and virulence gene detection,and the pathogenicity of the isolated bacteria was further evaluated by animal experiments.In result,the strain was gram-negative short bacilli,and the biochem-ical tests of glucose,urea,peptone water,citrate and lysine were positive,and it was preliminarily identified as Klebsiella bacteria.The sequencing results of PCR amplification products of bacterial universal primers showed that the homology between the bacteria and Klebsiella pneumoniae from broiler chickens in Pakistan was 99.77％,and the isolated strain was further identified as Klebsiella pneumo-niae.The results of drug sensitivity test showed that the strain of Klebsiella pneumoniae had strong resistance to tetracycline,erythromycin,azithromycin,penicillin,ampicillin and lincomycin,and was not sensitive to streptomycin and kanamycin.The bacteria carried 3 drug resistance genes and 6 viru-lence genes,and had strong pathogenicity to BALB/c mice.The mortality rate was 100％at 7.0× 108CFU/mL challenge.In conclusion,in this study,a strain of Klebsiella pneumoniae was isolated from dead piglets infected with PRRSV,which had multiple drug resistance and strong pathogenicity.This study shows that Klebsiella pneumoniae is an important secondary pathogen of PRRSV infection,which has im-portant guiding significance for the prevention and treatment of secondary bacterial infection in PRRSV positive pigs.