一起介水传播伤寒沙门菌疫情中3种水样前处理方法的初步应用分析

Preliminary application of three water pretreatment methods in a water-borne Salmonella typhi epidemic

目的对2022年北京市某区一起伤寒沙门菌疫情中涉及的饮用水样本,进行3种样本前处理方法的比较,为水样本伤寒沙门菌的检测处理提供参考。方法采集公寓楼供水管道5个位点的水样本各125 L,分别采用浓缩培养基直接增菌法、微生物快速富集法及微生物快速富集联合增菌法进行水样本前处理,然后提取核酸,采用肠道病原体微流体芯片进行初步筛查,初筛阳性样本再采用伤寒沙门菌实时荧光定量PCR方法进行复核,并同时将阳性样本接种于选择性培养基,将分离到的菌株与病人分离的伤寒沙门菌进行病原学分析。结果采用浓缩培养基直接增菌法处理的2号水样本检测到伤寒沙门菌,且测序分析结果与病人分离菌株一致;采用微生物快速富集法处理的2号和3号水样本,检测到除伤寒沙门菌之外的其他肠道病毒和寄生虫;采用微生物快速富集联合增菌法处理的水样本未检测到肠道病原体。结论本次疫情处理过程中,采用浓缩培养基直接增菌法能更好地检测到水体中的伤寒沙门菌。

Objective To compare the differences of 3 pretreatment method of drinking water samples involved in a Salmonella typhi(S.typhi)epidemic occurred in a district of Beijing in 2022,so as to provide a reference for the detection of S.typhi in water samples in the future.Methods The water samples of 125 L were collected from each of five sites in the water supply pipeline of the apartment building.The water samples were pretreated by direct enrichment method with condensed culture medium,rapid microbial concentration method and the rapid microbial concentration combined with enrichment method respectively,and nucleic acids were extracted.The nucleic acids were preliminarily screened by microfluidic chip for intestinal pathogens.The screening positive samples were checked by real-time PCR and the positive samples were inoculated into selective culture media.The etiological analyses were applied for strains isolated from the water samples and the patients.Results S.typhi was detected in No.2 water sample treated by direct enrichment method with condensed culture medium,and the sequencing result was in consistent with those of strains from patients.Some enteroviruses and parasites other than S.typhi were detected in No.2 and No.3 water samples treated by rapid microbial concentration method.No intestinal pathogen was detected in the water samples treated by rapid microbial concentration combined with enrichment method.Conclusions In the process of the epidemic management,the direct enrichment method with condensed culture medium was better in detecting Salmonella typhi in water.