上海市山夫登堡沙门菌流行特征和分子分型研究

Study on the epidemiological characteristics and molecular typing of Salmonella enterica subsp. enterica serovar Senftenberg in Shanghai

目的分析上海市2006—2007年山夫登堡沙门菌分离株的分子流行病学特征。方法追溯2002--2007年山夫登堡沙门菌食品分离株的来源；对2005--2007年从腹泻病例分离的山夫登堡沙门菌进行生化和hilA、invA基因表型鉴定、药敏试验、Riboprinter （RP）核糖体分型和脉冲场凝胶电泳（PFGE）分析。结果2006年山夫登堡沙门菌列上海市非伤寒沙门菌监测确认病例第3位，2002--2005年的食品分离株主要源自猪和牛肉制品。所有腹泻病例分离株除四环素（75．6％）外对其他抗生素均有较高敏感性。经RP和PFGE分子分型将硫化氢和hilA、invA基因全部有和无的两组菌株分别归属两类在遗传学上相对独立的克隆族。34株腹泻病例分离株分为16种PFGE带型，以同源程度较高的4型（4株）、5型（1株）、6型（6株）、7型（1株）共12株菌和11型（3株）、17型（5株）、23型（5株）共13株菌等优势带型聚类成2个克隆族。结论2006年上海市山夫登堡沙门菌感染病例是经过一定时间积累演变，由2个不同表型PFGE克隆族菌株构成较为少见的多点暴发。2007年病例大幅减少和未监测到同一时期食品污染源的结果表明，菌株存在遗传克隆的不稳定性和传播途径的复杂性。

Objective To study the molecular epidemiological characteristics of Salmonella enterica subsp, enterica serovar Senftenberg （Salmonella senftenberg） in Shanghai, from 2006 to 2007. Methods A retrospective analysis in 2006 and 2007 was performed to explore the source of food-borne Salmonella senfienberg. The isolates from diarrhea patients between 2006 and 2007 were identified, including biochemical test, hilA and invA gene phenotyping, drug susceptibility, Riboprinter （RP） and pulsed-field gel electrophoresis （PFGE）. Results Of the diarrhea patients isolates in the monitoring program on non-typhi Salmonella infection in the year of 2006 in Shanghai, number of patients caused by Salmonella senftenberg ranked the third. The stock of Salmonella senfienberg food-born isolates were derived from swine and beef products between 2003 and 2005.All of the strains from diarrhea patients were susceptible to antibiotics except tetracylina （75.6%）. With RP and PFGE molecular typing, the two groups （with hydrogen sulfide and hilA, invA gene or without） could be divided into two different independent clone cluster in genetics. 34 strains of diarrhea were divided into 16 PFGE typing-patten, and among them 12 strains including type 4 （4 strains）, type 5（1 strains）, type 6（6 strains）, type 7（1 strains） and 13 strains including type 11 （3 strains）, type 17 （5 strains）, type 23 （5 strains） were two different dominant clone cluster. Conclusion The epidemic of Salmonella senftenberg within 2006 might have been the result of a long period of case occurrence in Shanghai. This rare outbreak belonged to a cluster of outbreaks caused by two different PFGE clone clusters. Data suggested that the genetic clone of Salmonella senftenberg might have been unstable and the source of contamination were complicated, with the characteristics as the obvious decreasing number of patients, with no food-borne isolates in 2007.