副猪嗜血杆菌流行病学调查及两株分离株耐药性和致病性分析

为了解山东地区副猪嗜血杆菌病的流行情况和流行菌株的生物学特性及致病性,将2016-2018年山东省12个地区送检的103个发病猪的病料进行细菌分离,并对疑似菌株进行形态学观察、PCR鉴定及血清型鉴定,对两株流行菌株进行了培养特性观察、生化特性鉴定、药敏试验及致病性研究。最终分离获得29株副猪嗜血杆菌,分离率为28.16%,其中血清型4型和5型最为流行,其次是1型和12型。该病多发于春秋两季,31~50日龄的仔猪感染率最高。两株流行菌株LZ株和LC株均对青霉素类、头孢类等药物高度敏感,LZ株对庆大霉素、卡那霉素等中度敏感,对林可霉素、链霉素不敏感,LC株对庆大霉素、林可霉素等中度敏感,对卡那霉素、链霉素不敏感;生化特性试验结果显示,LC株和LZ株的硝酸盐还原试验、接触酶试验、葡萄糖发酵试验以及果糖发酵试验的结果均为阳性,吲哚试验、氧化酶试验、甘露醇发酵试验的结果均为阴性;动物致病性试验表明LZ株和LC株均具有较强的毒力,最小发病剂量分别为4.5×10^9 CFU和6.0×10^9 CFU。该研究为副猪嗜血杆菌病的防治提供了重要的参考依据。

Epidemiological Investigation of Haemophilus Parasuis and the Drug Resistance and Pathogenicity Analysis of Two Isolates

In order to find out the latest prevalence of Haemophilus parasuis in Shandong Province,the disease materials of 103 diseased pigs sent from 12 regions of Shandong Province in 2016-2018 were identified by bacterial isolation,and the suspected strains were observed by morphological observation.Besides,the isolated strains were subjected to PCR and serotype identification.These two epidemic strains were researched by observing culture characteristics and biochemical characteristics,testing drug sensitivity and pathogenicity.Finally,29 strains of Haemophilus parasuis were isolated,and the isolation rate was 28.16%.Among them,serotype 4 and serotype 5 were the most popular isolates,followed by serotype 1 and serotype 12.Additionally,Haemophilus parasuis mainly occurred in spring and autumn,the infection rate of piglets with 3l^50 days old was the highest.Both LZ strain and LC strain were highly sensitive to penicillins and cephalosporins,etc.,LZ strain was moderately sensitive to gentamicin,kanamycin,etc.,and was least sensitive to lincomycin and streptomycin,LC strain was moderately sensitive to gentamicin,lincomycin,etc.,and was least sensitive to kanamycin and streptomycin;The results of nitrate reduction test,catalase test,glucose fermentation test and fructose fermentation test of LC strain and LZ strain were all positive,the results of oxidase test and mannitol fermentation test of these two isolates were all negative,respectively;The animal pathogenicity test showed that both LZ strain and LC strain had strong virulence.The minimum doses of LZ strain and LC strain were 4.5×10^9 CFU and 6.0×10^9 CFU,respectively.This study provides an important reference for the prevention and treatment of Haemophilus parasuis.