甲型和乙型副伤寒同时暴发流行事件中菌株分子分型、毒力及耐药特征分析

Analysis of molecular typing,virulence and drug resistance features of bacterial strains in simultaneous outbreaks of paratyphoid fever A and B

目的对一起甲型和乙型副伤寒同时暴发流行事件中菌株的分子分型、毒力及耐药特征进行分析,为不同型别副伤寒同时传播的防治提供参考依据。方法回顾分析2018年9月至11月新疆生产建设兵团医院就诊的副伤寒确诊病例31例。对分离菌株进行血清学分型及药物敏感试验,采用多重PCR、脉冲场凝胶电泳、多位点序列分析进行分子分型,并检测毒力基因及耐药基因。结果31例确诊病例共分离出32株副伤寒沙门菌,血清学分型分为甲型19株、乙型13株,所有菌株对环丙沙星中介率为100%。11株代表菌株的M-PCR分子分型与血清学分型结果一致;甲型与乙型副伤寒沙门菌的PFGE指纹图谱均一致;甲型副伤寒沙门菌MLST为ST85型,乙型副伤寒沙门菌MLST为ST86型;所有菌株均携带毒力岛SPI1~SPI5代表基因invA、sitC、sseL、sifA、mgtC、siiE、sopB和调节基因phoP,甲型副伤寒沙门菌还携带三聚体结构的伤寒毒素(cytolethal distending toxin,CDT)基因cdtB、pltA、pltB,毒力质粒基因pefA、prot6E、spvB检测均为阴性。结论甲型和乙型副伤寒沙门菌同时传播具有致病性强及环丙沙星药物敏感性差的特点,应引起临床及实验室的高度关注。

Objective To investigate the molecular typing,virulence,and drug resistance features of bacterial strains in a simultaneous outbreak of paratyphoid fever A and B,and then provide evidence for the prevention and treatment of the simultaneous transmission of different types of paratyphoid fever.Methods The clinical data of 31 patients confirmed as paratyphoid fever in the Hospital of Xinjiang Production and Construction Corps from September 2018 to November 2018 were retrospectively analyzed.The isolated strains were performed serotyping and drug sensitivity tests.The molecular typing and the detection of virulence and drug resistance genes were carried out by multiplex PCR,pulsed-field gel electrophoresis(PFGE),and multilocus sequence typing(MLST).Results A total of 32 strains of Salmonella paratyphi were isolated from 31 patients,with 19 strains classified as type A and 13 as type B.The intermediate rates of all strains against ciprofloxacin were 100%.The molecular typing and serotyping results of 11 representative strains were consistent.The PFGE fingerprints of Salmonella paratyphi A and B were also consistent.The MLST of Salmonella paratyphi A was ST85,and that of Salmonella paratyphi B was ST86.All strains carried virulence island SPI1-SPI5 representative genes such as invA,sitC,sseL,sifA,mgtC,siiE,and sopB,and regulatory gene phoP.Salmonella paratyphi A also carried cytolethal distending toxin(CDT)genes with trimeric structure such as cdtB,pltA,and pltB.The virulence plasmid genes such as pefA,prot6E,and spvB were all negative.Conclusion The simultaneous transmission of Salmonella paratyphi A and B has the characteristics of high pathogenicity and poor sensitivity to ciprofloxacin,which should be highly concerned by clinical and laboratory personnel.