上海市蒙得维的亚沙门菌流行特征研究

Molecular epidemiology and drug susceptibility of Salmonella Montevideo in Shanghai

目的研究蒙得维的亚沙门菌的耐药及分子流行病学特征。方法基于上海市针对人群和食源、环境沙门菌的监测基线,分析蒙得维的亚腹泻和食源环境株的耐药表型和分子型特征。结果蒙得维的亚在本地区的人源和食源沙门菌型数据库中列第24位（32株）和32位（13株）。经实验室确诊的28例蒙得维的亚病例均符合食源性感染特征,易感人群为5岁以下儿童和20~60岁男性,城郊地区高发。人源和食源株均发现对三代头孢（头孢他啶）耐药株,近5年中食源株的多重耐药（MDR）明显增多,28.1%的人源株对环丙沙星处于耐药临界值,来自境外动物制品的蒙得维的亚菌株对抗生素多数敏感。32株人源和13株食源株的分型聚类提示存在优势克隆簇,包括3起经回顾性鉴别诊断的蒙得维的亚的成人暴发,其中2起为多重耐药（MDR-ACSSuT）的克隆暴发。MDR-ACSSuT的人源流行株与甲鱼株之间存在高度的遗传同源性,与境外输入菌株间的耐药和分子型特征差异较大,2个不同克隆簇之间存在遗传进化关系。结论蒙得维的亚尚未在本地区成为优势种型,但其已通过贸易等方式不断输入国内,逐渐定殖于沿海地区的甲鱼养殖产业链和人群的消费食物链中,最终进化成稳定的MDR和非MDR克隆容易形成分散而隐蔽的食源性暴发。

Objective To study the molecular epidemiological characteristics and antibiotic susceptibility of Salmonella enterica serovar Montevideo（ S. Montevideo）. Methods The analysis was conducted by using the surveillance data in Shanghai Collect and analyze Salmonella surveillance database in Shanghai. Results S. Montevideo ranked 24th（ 32 isolates）among all Salmonella serotypes from human and 32nd（ 13 isolates） from food source in Shanghai,respectively. Twenty eight foodborne infections of S. Montevideo were laboratory confirmed among diarrheal cases. Children under 5 years old and male adults aged 20-60 years were more susceptible,and the incidence in suburb area was high. Antibiotic susceptibility test showed that both foodborne and human isolates were resistant to the third-generation cephalosporin（ Ceftazidime）. Moreover,m ulti drug resistant（ MDR） foodborne isolates increased significantly in recent five years,and 28. 1% of hum an sourced S. Montevideo isolates were interm ediate to ciprofloxacin. However,the isolates from foreign anim al products were m ostly sensitive to antibiotics. PFGE indicated that prevalent clones of S. Montevideo strains existed in Shanghai,including MDRACSSu T which caused two of three outbreaks in adults. MDR-ACSSu T isolates from human and turtles shared high homology,but quite different from foreign isolates. Phylogenetic relationship existed between the two different clone clusters. Conclusion S. Montevideo is not predominant in Shanghai,but it has been transmitted to China through trade and gradually colonized in coastal turtle cultivation and food chain. The MDR clones and non-MDR strains might cause sporadic outbreaks,which are difficult to detect.