上海市单核细胞增生李斯特菌基因分型及耐药性研究

Characterization,antimicrobial resistance and genetic traits of Listeria monocytogenes in Shanghai,China

目的了解上海市单核细胞增生李斯特菌(Listeria monocytogenes,LM)食品和临床分离株的毒力特点、耐药性及其基因特征。方法采用试管凝集法对89株LM食品和临床分离株进行血清分型,采用聚合酶链反应(PCR)方法对LM中7个毒力基因进行检测,采用琼脂扩散(K-B)法对其进行药敏试验,采用脉冲场凝胶电泳法(PFGE)对89株LM分离株进行分型研究。结果血清分型结果显示1/2a和1/2c是LM优势血清型。只有4株LM食品分离株对四环素显示耐药,其余均为敏感。89株LM食品和临床分离株都含有7种毒力基因。89株食品和临床分离株经双酶切分型可得40条不同的条带,且1株临床菌株的PFGE分型显示其为食品分离株的亚型。结论上海市LM分离株的耐药性并不严重,但是其均为产毒株,且PFGE分型结果显示临床菌株与食品分离株之间有较近的亲缘关系,这提示上海市LM分离株对公共卫生具有潜在的危险,需要对其加强监测。

Objective Listeria monocytogenes （L. monocytogenes） causes invasive diseases in humans and farm animals and is frequently isolated from numerous food types. The aim of the present study was to observe the antimicrobial resistance and genetic traits of L. monocytogenes isolated from food and seven clinical samples. Methods The serotypes of 89 strains of L. monocytogenes were performed by using the tube agglutination test. Virulence genes were analyzed by PCR K-B test was used to determine the antimicrobial resistance and pulsed field gel electrophoresis （PFGE） was used to analyze the gene traits. Results The serotyping analysis revealed that 1/2a and 1/2c were the predominant serotypes. Only 4 strains （4.50/00） isolated from food were resistant to tetracycline. All isolates from food and clinical samples were positive for seven virulence genes. The isolates were grouped into 40 pulse types （PTs） according to PFGE analysis. Certain types were relatively widely disseminated within all food-types and one clinical isolate was identified as a subtype of a food isolate. Conclusions These findings indicate that L. monocyotgenes strains isolated in Shanghai pose a potential public health risk, therefore require an intensive epidemiological and ecological monitoring to ensure safety.