出入境动物源性食品中单增李斯特菌的多位点序列分型分析

对出入境动物源性食品中分离的单增李斯特菌进行多位点序列分型（mutilocus sequence typing，MLST）分析，了解其序列型分布特点及不同菌株之间的亲缘关系。提取单增李斯特菌基因组DNA，选择其7 个管家基因进行聚合酶链式反应扩增并测序。将测序结果截成标准序列的长度后上传到MLST数据库进行比对分析，获得7 个管家基因的等位基因谱和序列分型编码，并将结果采用不加权算术平均组对（unweighted pair group method usingarithmetic averages，UPGMA）法进行聚类分析。89 株单增李斯特菌共获得51 个STs，其中26 个为新获得的STs（STnew1～STnew26）；数量最多的5 个STs为ST8（9.0%），ST121（9.0%）、ST7（5.6%）、ST87（5.6%）及新发现的STnew3（7.8%）；其中ST456、ST34、ST343、ST19、ST517、ST201、ST98、ST330和ST73为在国内首次获得。采用UPGMA算法得到的进化树可将89 株菌株分为3 大类群，分类的结果与单增李斯特菌血清学家系分类结果一致。MLST结果对了解出入境动物源性食品中分离的单增李斯特菌的亲缘关系及流行病学溯源有重要意义。

Multilocus Sequence Typing of Listeria monocytogenes Isolated from Imported and Exported Animal-Derived Foods

This study was devised to understand the sequence types (STs) and the genetic and evolutionary relationship ofdifferent Listeria monocytogenes isolated from imported and exported animal-derived food samples. Seven house-keepinggenes were selected as target genes for PCR amplification. Sequencing, analysis and comparison of the 7 housekeepinggenes were conducted. Their alleles and STs codes were obtained, and their evolutionary relationships were analyzed byunweighted pair group method using arithmetic average (UPGMA). A total of 51 STs were obtained from 89 strains bymultilocus sequence typing (MLST), among which 26 were novel. The 5 most common STs were ST8 (9.0%), ST121(9.0%), ST7 (5.6%) and ST87 (5.6%) as well as the novel STnew 3 (7.8%). ST456, ST34, ST343, ST19, ST517, ST201,ST98, ST330 and ST73 were found for the first time in China. The evolutionary relationship analyzed by UPGMA methodshowed that the isolates were grouped into 3 clusters, which were consistent with three lineages classified by serotype ofL. monocytogenes. MLST is a useful method to evaluate genetic evolution. This method is applicable to study the populationstructure and epidemiological traceability of L. monocytogene isolates from imported and exported animal-derived food samples.