波摩那沙门菌耐药及分子流行病学特征研究

Study on the molecular epidemiology and antibiotic resistance of Salmonella enterica serovar Pomona

目的 研究波摩那沙门菌的耐药分子流行病学特征.方法 基于上海市网络实验室连续性监测腹泻病例和环境食品及广西地区爬行动物监测的波摩那沙门菌进行抗菌药物耐药和脉冲场凝胶电泳（PFGE）分析.结果 2005-2012年上海市网络实验室诊断临床病例分离沙门菌4 553株,居前10位的20个血清型均为A～F群,波摩那沙门菌在少见的非A～F群中仅次于旺兹沃思沙门菌排第2位,并对低年龄组人群普遍易感,症状有血样便和二次感染现象.确认食源环境沙门菌1 805株,前10位血清型明显比人源株更具多样性,波摩那沙门菌在少见型中列第3位,多源自甲鱼、海水贝壳类和爬行动物.波摩那沙门菌非人源分离株耐药性显著高于人源株,PFGE结果分属A和B不同克隆簇.克隆A为非流行株的多重耐药株,菌株多源自淡水养殖鱼类;克隆B为不耐药的流行株,分为B-Ⅰ（分离自低年龄组）和B-Ⅱ（分离自成年组）2个亚簇,前者与海水贝壳类动物、陆龟、蜥蜴分离株同源,后者与海水贝壳类动物分离株同源,其中1例人源株对8种抗生素呈多重耐药.结论 波摩那沙门菌属少见菌型,但对婴幼儿有较高致病性.上海市近期分离的波摩那沙门菌与2005年病例菌株存在遗传进化关系,需要对致病克隆加强监测并预警进食海鲜和爬行动物的感染风险.

Objective To study the epidemiological characteristics and antibiotic resistance of Salmonella enterica serovar Pomona （S.Pomona）.Methods Antimicrobial susceptible testing （AST） and pulsed field gel electrophoresis （PFGE） methods were used to analyze on S.Pomona strains that were isolated from diarrhea cases through the diarrhea network monitoring program,environment and food samples in Shanghai as well as from reptiles in Guangxi Zhuang Autonomous Region.Results 4 553 clinic Salmonella （S.） strains were isolated from the Shanghai network laboratories from 2005 to 2012.The top 10 serotypes would include 20 serotypes all belonged to A-F groups,while S.Pomona was next to S.Wandsworth,according to the non-A-F groups.Young children seemed to be susceptible to S.Pomona,and might cause bloody stools and super-infection.The top 10 serotypes from 1 805 foodborne Salmonella strains were significantly more extensive than those from the human S.Pomona strains,followed by those rare serotypes which were mostly isolated from turtle,sea-shellfish and reptiles.Antibiotic resistance of S.Pomona strains from other sources were significantly more severe than those from human samples,and belonged to A and B clones by means of PFGE.Clone A strains were non-epidemic strains which showed multi-drug resistance （MDR） to antimicrobials.Clone B was the main epidemic-causing strain that not resistant to drugs,which consisting B-Ⅰ from young-age-groups and B-Ⅱ were from the seniors.B-Ⅰ strains were homologous to those from shellfish,tortoises and lizards,while B-Ⅱ strains only showing homology to those from shellfish.One S.Pomona strain—MDR,isolated from human was homologous to 8 antimicrobials.Conclusion S.Pomona was a quite common serotype among those rare serotypes,which showed higher pathogenicity to infants while genetic evolution might take place when comparing them with the strains isolated from the clinics in 2005.Surveillance programs should be intensified along with the early warnings systems on infections which were from seafood and reptiles.