一起布利丹沙门菌食物中毒的调查

Study on an outbreak of food poisoning caused by Salmonella blegdam

目的查明导致本次食物中毒事件的食物种类、致病因子及传染源。方法在临床诊断病例中，随机抽取50例作为病例组，随机选择参加宴席且无任何临床症状的50人作为对照组，开展病例对照研究，并分析导致本次事件的危险食物。结果本次食物中毒的罹患率为43．4％（132／304），86．0％（43／50）的病例和34．0％（17／50）的对照食用过猪头肉凉拌粉条（OR=12．0，95％CI：4．4～32），进一步对食用过猪头肉凉拌粉条者分析其剂量反应关系，趋势X^2=21．06，P=0．00。94．0％（47／50）的病例和68．0％（34／50）的对照食用过蘑菇炖鸡（OR=7．4，95％CI：2．0～27），不存在剂量反应关系。病例组和对照组食用其余食物的差异无统计学意义（P〉0．05）。对猪头肉凉拌粉条和蘑菇炖鸡与发病之间的关系进行又生分析，以两种食物均未食用者作为参照，结果表明，单食用两种食物之一者发病危险度的点值估计均升高，但差异均无统计学意义；而两种食物均食用者发病风险大大增加（0R=38，95％CI：4．5～320），差异有统计学意义。19份标本检测肠道致病菌中3份病例肛拭子和1份猪头肉凉拌粉条检出布利丹沙门菌。结论该事件是因参加宴席的人食用被布利丹沙门菌污染的猪头肉凉拌粉条或蘑菇炖鸡引起的细菌性食物中毒，其原因可能为食品加工过程不规范所致。

Objective To identify the bacterial pathogen in food and the source of infection that might be responsible for a food poisoning outbreak. Methods All the probable cases that had attended the banquet in a villige of Sichuan province who had developed fever （ ~37.5 ~C ）, diarrhea （ ~3 times/day） and vomiting since August 1, 2009, were identified. A case-control study was conducted to identify the foods that might be responsible for this food poisoning event. 50 cases were randomly selected from the probable cases and 50 controls were randomly selected from those without the symptoms. Results The attack rate of this food poisoning event was 43.4% （132/304）. 86.0% （43/50） of the cases and 34.0% （17/50）of the controls had eaten pork-mixed-vermicelli （OR= 12.0, 95%CI： 4.4-32）. Data from further tests showed that dose-effect relation existing between eating pork mixing vermicelli behavior and the incidence rates （Chi-square trend： 22=21.06, P=0.00） of the disease. 94.0% （47/50） of the cases and 68.0% （34/50） of the controls had eaten mushroom braising chicken （0R=7.4, 95%CI： 2.0-27）. Data from the crossover analysis showed that there appeared an effect modification between behaviors of eating pork-mixed-vermicelli and eating mushroom braising chicken. Three cases were detected carrying Salmonella blegdam from their anus swabs and the same bacteria type was also detected in the pork-mixed-vermicelli. Conclusion This outbreak of salmonellosis was caused by Salmonella blegdam contaminated pork-mixed-vermicelli or mushroom braising chicken during food processing.