广东省食品中单核细胞增多性李斯特菌脉冲场凝胶电泳技术分子分型的研究

Molecular typing of Listeria monocytogenes isolated from foodstuff in Guangdong province by pulsed-field gel electrophoresis

目的应用脉冲场凝胶电泳技术（PFGE）对广东省食品中分离的单核细胞增多性李斯特菌（Lm）进行分子分型，并建立PFGE数据库。方法参照美国PulseNet的Lm PFGE分子分型标准方法进行检测。应用BioNumerics软件对不同食物种类、时间和地点的分离株进行比对，分析菌株之间的相关性。结果107株Lm分成41个PFGE型，型别较为分散；从鸡肉中分离的菌株数最多（37株），PFGE分型也最多（19个）；冷藏和冷冻食品的分离率较高，其中有26株菌仅存在1-2个电泳条带的差异，相似度极高；韶关和惠州地区分离的Lm存在着地区特异性；随时间变迁，部分菌株仍存在不同程度的相关性。结论广东省食品中分离的Lm在整体上表现出较大的遗传多样性，但部分菌株有不同程度的相关性。

Objective To establish molecular typing of Listeria monocytogenes isolates by pulsed-field gel electrophoresis （PFGE） for studying the epidemiologic characteristics of Listeria monocytogenes isolated from foodstuff in Guangdong province and to build up PFGE typing database of Listeria monocytogenes isolates for identifying the infectious resource of the outbreaks and other epidemiologic investigation. Methods “Standardized Protocol for Molecular Subtyping of Listeria monocytogenes by PFGE” was followed. BioNumerics software was applied on image analysis, database establishment, comparative and corresponding analysis. Results 107 Listeria monocytogenes isolates were typed by PFGE, 41 PFGE types were observed among the isolates. The PFGE types were dispersive among these isolates. Listeria monocytogenes isolates were most frequently isolated in raw chicken while the most PFGE types were found in this type of food. The positive rate was relatively high in cold and iced foods. Only 1-2 DNA fragment difference occurred in 26 Listeria monocytogenes isolates by PFGE, so high degree of relatedness remained among these isolates. There were unique PFGE patterns in the regions of Shaoguan and Huizhou. From time to time, a number of isolates remained close relationship. Conclusion PFGE typing of the 107 Guangdong Listeria monocytogenes isolates demonstrated relative genetic diversity but a number of the isolates showed close relatedness.