单增李斯特菌动物源性食品分离株对苯扎氯铵的抗性及分子特征分析

Analysis of resistance to benzalkonium chloride and molecular characteristics of Listeria monocytogenes isolates from animal origin food samples

目的了解不同血清型、ST型单增李斯特菌动物源性食品分离株对苯扎氯铵抗性及携带耐消毒剂基因情况。方法采用多重PCR结合血清凝集法对单增李斯特菌动物源性食品分离株进行血清分型,用多位点序列分型(MLST)技术进行分子分型,用平板法检测苯扎氯铵对单增李斯特菌的最小抑菌浓度(MIC),使用PCR检测其耐消毒剂相关基因qacH、bcrABC、MdrL、emrE。结果58株单增李斯特菌动物源性食品分离株包含4种血清分型,以1/2a血清型为主;可分为2个谱系,10个克隆群(CC),ST9、ST8、ST87为主要序列型;8株菌株的苯扎氯铵MIC为15μg/mL,其中6株为1/2a血清型,5株序列型为ST8。48株菌株的苯扎氯铵MIC为10μg/mL。75.86%菌株携带MdrL基因,1.72%菌株携带qacH基因。未检出耐消毒剂基因bcrABC、emrE。结论单增李斯特菌动物源性食品分离株对苯扎氯铵的敏感性下降,其中血清型1/2a、序列型ST8的单增李斯特菌对苯扎氯铵的MIC值更高。

Objective To investigate the resistance to benzalkonium chloride of different serotypes and ST type of Listeria monocytogenes isolated from animal origin food samples and the carrying of disinfectant resistance genes.Methods Multiple PCR combined with serum agglutination method was used for serotyping of Listeria monocytogenes isolated from animal origin food samples.Multilocus-sequence typing(MLST)technology was used for molecular typing.The minimum inhibitory concentration(MIC)of benzalkonium chloride against Listeria monocytogenes was detected by plate method.The disinfectant resistance related genes qacH,bcrABC,MdrL,emrE were detected by PCR.Results 58 strains of listeria monocytogenes isolated from animal origin food samples contained 4 serotypes,mainly 1/2 a serotype;they could be divided into 2 lineages and 10 clonal complexes(CC),and ST9,ST8 and ST87 were the main sequence types;MIC of benzalkonium chloride of 8 strains was 15μg/mL,of which 6 strains were 1/2 a serotype and 5 strains were ST8 sequence type.MIC of benzalkonium chloride of 48 strains was 10μg/mL.75.86%of the strains carried MdrL gene and 1.72%carried qacH gene.No disinfectant resistant genes bcrABC and emrE were detected.Conclusion The susceptibility of Listeria monocytogenes isolated from animal origin food samples to benzalkonium chloride decreases,and the MIC of Listeria monocytogenes with serotype 1/2 a and sequence type ST8 to benzalkonium chloride is higher.