1起非O1/非O139群霍乱弧菌感染性腹泻暴发疫情的病原学分析

Etiological analysis on an outbreak of non-O1/ non-O139 Vibrio cholerae infectious diarrhea

目的 对1起非O1/非O139群霍乱弧菌感染性腹泻疫情进行病原体分离,分析菌株的病原学特征、毒力因子和同源性。方法 选择2021年8月3日广州市某区某中学报告的1起霍乱弧菌感染性腹泻疫情病例资料,采集20份未痊愈学生病例的肛拭子样本,选择性增菌与培养分离致病菌,并对分离菌株进行形态特征分析、生化鉴定、血清学鉴定、毒力基因检测,进行基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)分析与聚类分析。结果 12株分离菌株形态特征与霍乱弧菌相符,生化鉴定、血清学鉴定为非O1/非O139群霍乱弧菌。实时荧光PCR检测霍乱弧菌O1群与O139群均为阴性,霍乱毒素ctxA阴性,霍乱溶血素hlyA阳性。细菌蛋白质谱比对结果表明,12株非O1/非O139群霍乱弧菌在(4 275±5)、(5 119±5)、(6 161±5)、(6 272±5)、(7 157±5)m/z区间均采集到特征性质谱峰,质谱图相似。菌株蛋白质谱聚类分析提示301、01、303、302、307、309、310、02和308等9株非O1/非O139群霍乱弧菌相似度高于90%,归属同一类。结论 此次腹泻疫情的病原体为非O1/非O139群霍乱弧菌,均携带hlyA,未检出ctxA。

Objective To isolate pathogens from a non-O1/non-O139 group Vibrio cholerae-infected diarrhea outbreak and analyze strains for pathogenic characteristics,virulence factors,and homology.Methods Case data of vibrio cholera diarrhea reported from a middle school in a district of Guangzhou city on August 3,2021 was selected.A total of 20 anal swab samples from unhealed students were collected for selective enrichment and culture to isolate pathogenic bacteria.Morphological characteristics,biochemical identification,serological identification and virulence gene detection were carried out on the isolated strains,and matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF MS) analysis and cluster analysis were carried out.Results The 12 isolated strains were identified as non-O1/non-O139 Vibrio choleraeby biochemical and serological identifications.The results of real-time fluorescent PCR were negative for Vibrio cholerae O1 group and O139 group,negative for cholera toxin ctxA,positive for cholera hemolysin hlyA.The comparison of bacterial protein spectra showed that 12 strains of non-O1/non-O139 Vibrio cholerae were detected in the range of(4 275±5),(5 119±5),(6 161±5),(6 272±5),(7 157±5) m/z,and their characteristic spectral peaks were similar.The protein spectrum cluster analysis indicated that 301,01,303,302,307,309,310,02 and 308 strains of non-O1/non-O139 group Vibrio cholera were more than 90% similar and belonged to the same category.Conclusion The pathogens in this diarrhea outbreak are non-O1/non-O139 group Vibrio cholerae,all of which carried hlyA and no ctxA was detected.