一起疑似产气荚膜梭菌腹泻暴发事件实验室检测分析

Laboratory detection and analysis of a suspected diarrhea outbreak caused by Clostridium perfringens

目的分析一起疑似由产气荚膜梭菌导致腹泻暴发事件的实验室检测结果,为产气荚膜梭菌食物中毒实验室检测策略的改进奠定基础。方法采集暴发事件中4例病例肛拭子样本,应用荧光PCR方法检测肛拭子及其增菌液中cpa基因与cpe基因。对肛拭子样本进行产气荚膜梭菌分离培养,对部分分离单菌落进行产气荚膜梭菌毒力基因检测和脉冲场凝胶电泳(PFGE)分子分型。结果4例病例样本中均检测到cpa基因和cpe基因。从病例1样本中挑取并鉴定为产气荚膜梭菌的18个单菌落中获得1个cpe+菌落,构成比为5.56%(1/18);从病例2样本中挑取并鉴定为产气荚膜梭菌的6个单菌落中获得1个cpe+菌落,构成比为16.7%(1/6);病例3未分离到cpe+菌落,病例4未分离到产气荚膜梭菌。11株产气荚膜梭菌菌株包括A型和C型两种,包含5种PFGE带型,分离自病例1和病例2的cpe+阳性菌株PFGE带型一致。结论本次暴发事件可能由产气荚膜梭菌导致,综合使用各种实验室检测方法可在产气荚膜梭菌诊断标准滞后的情况下协助暴发事件分析。

Objective To provide basic data for modification of laboratory testing for outbreaks caused by Clostridium perfringens(C.perfringens),a diarrhea outbreak that may have been caused by polyclonal infection of C.perfringens was analyzed.Methods Anal swab samples of 4 patients with diarrhea were collected.cpa and cpe genes and C.perfringens in original swab samples and enriched samples were detected via real time PCR.Toxin gene test and pulsed field gel electrophoresis(PFGE)were performed for some C.perfringens isolates.Results cpa and cpe genes were positive in samples of 4 patients.One cpe+isolate was obtained from 18 isolates of C.perfringens from patient 1,and the composition ratio was 5.56%(1/18).One cpe+isolate was obtained from 6 isolates of C.perfringens in patient 2,and the composition ratio was 16.7%(1/6).No cpe+isolate was obtained from patient 3,and C.perfringens was not isolated from patient 4.Two types(A type and C type)and 5 PFGE patterns were identified in 11 isolates of C.perfringens.Two cpe+isolates from patient 1 and patient 2 had identical PFGE patterns.Conclusion This outbreak might have been caused by C.perfringens.Considering the delays caused by the implementation of diagnostic standards,comprehensive use of laboratory detection methods can improve the response time of outbreak analysis.