北京市昌平区食源性单增李斯特菌特征分析

Characteristics of Listeria monocytogenes isolated from foods in Changping district of Beijing

目的了解北京市昌平区食源性单增李斯特菌(Lm)的毒力基因携带情况、抗生素敏感性及分子特征。方法对2010-2016年12类食品中分离的22株Lm进行血清型、毒力基因、抗生素敏感性、多位点序列分型(MLST)和脉冲场凝胶电泳(PFGE)分析。结果 22株Lm分为5种血清型(以1/2c、3a血清型为主);19种毒力基因携带谱(T1~T19),毒力基因阳性数为6~12个;对氨苄西林、青霉素、美罗培南、复方新诺明、万古霉素和环丙沙星敏感,出现对四环素、红霉素耐药菌株;分为8个序列型(ST)(包括7个新型STA1~STA7),STA3为主要型别;分为17种PFGE带型,其相似系数为63.5%~100.0%,PTⅠ为主要PFGE带型。结论昌平区食源性Lm以1/2c、3a血清型为主,STA3为主要型别,PTⅠ为主要PFGE带型,其毒力基因的携带具有差异性,出现对四环素、红霉素耐药株,为食源性Lm的研究提供了参考。

Objective To understand the virulence genes,antibiotic resistances and molecular characteristics of Listeria monocytogenes. Methods A total of 22 L. monocytogenes strains isolated from 12 kinds of foods between 2010 and 2016 in Changping were used for serotyping,virulence genes detection,antibiotic susceptibility test,multi-locus sequence typing（MLST）and pulsed-field gel electrophoresis（PFGE）. Results The 22 L. monocytogenes strains belonged to5 serotypes,1/2 c and3 a were the predominant serotypes. A total of 19 virulence gene profiles（T1-T19）were found,and most strains carried 6-12 kinds of virulence genes. All the L. monocytogenes isolates were sensitive to ampicillin,penicillin,meropenem,sulfamethoxazde,vancomycin and ciprofloxacin,and a few strains were resistant to tetracycline and erythromycin. The result of MLST showed 8 different sequence types,including 7 new STs,i.e. STA1-STA7,and the predominant ST was STA3.Seventeen PFGE patterns were found with a similarity coefficient from 63.5%-100.0%,and the PTⅠwas predominant.Conclusion Most L. monocytogenes isolates isolated in Changping belonged to serotype 1/2 c and 3 a,STA3 and PTⅠstrains were predominant. Most strains had different virulence genes profiles. Resistance to tetracycline and erythromycin were found in a few L. monocytogenes isolates. Our data provides a reference for the study of foodborne Listeria spp.