2017年我国4个省份屠宰场猪链球菌的分离鉴定及耐药性分析

Identification and antimicrobial resistance of Streptococcus suis in slaughterhouses from four different provinces of China

为研究我国不同地区屠宰场猪链球菌的流行情况,本研究于2017年分别从河南、黑龙江、广东、宁夏4个地区大型屠宰场采集健康猪肺脏样品578份,进行猪链球菌的分离鉴定、血清型分型;通过微量肉汤稀释法测定分离株的最小抑菌浓度(MIC);PCR方法检测分离菌的耐药基因和毒力基因;通过脉冲场凝胶电泳(PFGE)技术分析不同来源分离株间的亲缘关系。结果显示,从4省市共分离到猪链球菌46株,包括12种血清型和3种荚膜新型血清型,其中猪链球菌血清7型分离率最高,为30.4%,但不同地区血清型交叉密度较低。分离菌株表现出广泛耐药性,其中对红霉素、阿奇霉素、多西环素的耐药率较高,分别为91.30%、86.96%、86.96%,但分离株均对万古霉素敏感。红霉素类耐药基因erm和四环素类耐药基因tet的检出率均较高,其中erm(B)为97.83%,tet(O)为89.13%。PFGE结果显示不同地区分离菌株PFGE谱型差异明显,而同一地区分离菌株PFGE谱型相似或相同,提示同一地区猪链球菌存在克隆传播现象。本研究揭示了我国不同地区猪链球菌流行情况,为猪链球菌病的防控提供参考依据。

To investigate the prevalence of Streptococcus suis(S.suis)in slaughterhouses from different regions of China.A total of 578 healthy pig lung samples were collected from four commercial slaughterhouses distributed in Henan,Heilongjiang,Guangdong and Ningxia provinces,respectively in China in 2017.Then,the isolation and serotyping of S.suis were performed.The antimicrobial susceptibility test was carried out by microbroth dilution method.Antimicrobial resistance genes and virulence genes were detected by PCR.The relationship of all strains was analyzed by pulsed field gel electrophoresis(PFGE).The results showed that 46 S.suis strains were isolated and purified,including 12 serotypes and 3 novel capsular types.Among them,the isolation rate of S.suis serotype 7 was the highest(30.43%),but the cross density of serotypes was low in different regions.Most strains exhibited high resistance rates to erythromycin(91.30%),azithromycin(86.96%),doxycycline(86.96%),but all of them were sensitive to vancomycin.The detection rates of erythromycin and tetracycline resistance genes are higher,among which erm(B)and tet(O)were 97.83% and 89.13%,respectively.The results of PFGE showed that there were significant differences between the strains from different regions,but the relationship of isolates from the same region were closely related,with the same spectrum type,and suggested clonal transmission was existed in the same region.This study revealed the prevalence of S.suis in different regions of China and provided reference basis for the prevention and control of S.suis disease.