从一起疑似产气荚膜梭菌食源性疾病暴发调查反思实验室依赖的病因筛查思路

Self-examination of lab-dependent way in etiology screening in an investigation of a suspected foodborne outbreak of Clostridium perfringens

目的调查一起急性胃肠炎暴发的原因,并对当前基层疾病预防控制机构在食源性疾病暴发流行病学调查中有关样品和标本采集后,致病因子的筛查思路进行了分析探讨。方法制定病例定义,开展病例搜索和个案调查,采用描述性流行病学方法分析事件特征;开展病例对照研究探讨危险因素和现场卫生学调查追溯原因。采集病例标本和环境样品进行致病菌分离。结果共搜索病例43例,临床表现主要以腹泻(100.0%,43/43)、腹痛(93.0%,40/43)、恶心(32.6%,14/43)等为主。流行曲线符合点源暴发模式,可疑餐次为2013年9月12日午餐,病例对照研究结果提示烧鸭为可疑食物(OR=4.0,95%CI为1.04~15.23)。共采集各类样品和标本36份,在13份病例肛拭子中分离培养出产气荚膜梭菌5份,阳性率为38.5%。结论该事件为一起疑似产气荚膜梭菌食源性疾病暴发,可能危险因素为烧鸭烤熟后在室温下长时间(约5~6 h)缓慢冷却后受污染,且未经重新加热直接进食所致。建议加强对餐饮机构厨师的监督管理,防止类似事件再次发生。基层流行病学调查人员应摒弃"实验室依赖"的惯性思维,加强对各种致病因子"症状流行病学"知识的归纳总结,以降低在各种食源性疾病暴发中,因不熟悉疾病临床特征而导致的误判和漏检。

Objective To investigate an acute gastroenteritis outbreak and discuss the methodology of etiology screening.Methods Cases were identified according to the definition. Descriptive epidemiological approaches and case-control study designs were employed in the analysis. All the samples were tested for common pathogens by isolation. Results A total of43 cases were found. Epidemiological curve suggested that it was a point source outbreak and the major symptoms werediarrhea（ 100. 0%,43/43）,abdominal pains（ 93. 0%,40/43）,nauseous（ 32. 6%,14/43） and so on. Results From the case-control study revealed that the roast duck served at lunch on September 12 was suspectable. A total of 36 samples,including rectal swabs from patients,hand swabs from kitchen workers,leftover food and environmental swabs,were collected. Five samples（ collected from 13 patients） were positive. Conclusion This was a suspected foodborne outbreak of Clostridium perfringens. The possible cause was that the roast duck was contaminated by Clostridium perfringens when stored in the external environment at room temperature for about 5-6 h and was directly ate by patients without reheating. It is necessary to strengthen the supervision and administration of chefs,and improve health consciousness of the public to prevent such case. Investigators should abandon the ＂lab-dependent ＂ way and strengthen the summary of symptoms-based epidemiology related to a variety of agents so as to decreases the rate of erroneous diagnosis and misdiagnosis dued to the unfamiliar of symptoms of various foodborne diseases.