一起弗劳地柠檬酸杆菌引起的食物中毒病原鉴定及耐药性分析

目的 对一起突发食物中毒事件进行病原检测及耐药性分析,为突发食物中毒事件的应急处置提供参考。方法 对采集的样本按照GB 4789等标准方法进行致病菌检测,分离株采用VITEK2和基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）进行菌株鉴定,同时采用微量肉汤稀释法进行细菌药物敏感性试验,并对不同来源分离株进行脉冲场凝胶电泳（PFGE）分子分型,以BioNumerics软件分析菌株之间的相关性。结果 13份剩余食物和3份腹泻患者粪便经分离鉴定,有7份剩余食物样本的菌落总数、大肠菌群全部超标,有5份剩食物和2个病例的粪便中检出弗劳地柠檬酸杆菌,药敏试验结果显示,7株弗劳地柠檬酸杆菌对环丙沙星、四环素、氯霉素、庆大霉素、阿米卡星、头孢噻肟和美罗培南均敏感,但对氨苄西林完全耐药,无多重耐药现象;检出的7株弗劳地柠檬酸杆菌,经脉冲场凝胶电泳（PFGE）检测结果为：7株弗劳地柠檬酸杆菌的PFGE条带一致、同源性100%,显示为同一克隆。结论 本起食物中毒事件是由弗劳地柠檬酸杆菌导致的,通过飞行质谱方法可以快速、准确确定食物中毒的病原,利于感染性疾病的早期诊疗,建议加大相应的管理力度,提高食品安全意识,预防类似事件的发生。

Etiologic identification and drug susceptibility analysis of a Citrobacter freundii food poisoning event

Objective In order to provide reference for emergency treatment of a sudden food poisoning incident, pathogen detection and drug resistance analysis were carried out. Methods Diarrheal stool and surplus food samples were detected by GB 4789 and the isolates were identified by VITEK2 and matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), at the same time, the bacterial drug sensitivity test was carried out by using the method of microbroth dilution, and the isolates from different sources were molecularly classified by pulsed field gel electrophoresis (PFGE), and the correlation between the strains was analyzed by BioNumerics software. Results Totaly 13 leftovers and 3 diarrhea patients were isolated and identified, The total number of colonies and coliforms in 7 leftovers samples all exceeded the standard, and Citrobacter freundii was detected in 5 leftovers and 2 stools. The results of drug sensitivity test showed that seven strains of Citrobacter freundii were sensitive to ciprofloxacin, tetracycline, chloramphenicol, gentamicin, amikacin, cefotaxime and meropenem, but completely resistant to ampicillin, and there was no multiple drug resistance. The results of pulsed field gel electrophoresis (PFGE) showed that 7 strains of Citrobacter freundii had the same PFGE bands and 100% homology, showing the same clone. Conclusions This food poisoning incident was caused by Citrobacter freundii. The pathogen of food poisoning can be quickly and accurately determined by MALDI-TOF MS, which is beneficial to the early diagnosis and treatment of infectious diseases. It is suggested to strengthen the corresponding management, improve food safety awareness and prevent similar incidents.