阪崎肠杆菌是一种重要的食源性致病菌，可引起严重的新生儿脑膜炎，坏死性小肠结肠炎和菌血症等疾病。传统观念认为配方奶粉是婴幼儿感染该菌的主要来源，但这无法解释2011年发生在美国的阪崎肠杆菌感染等事件。我们研究发现，小麦及其制品中阪崎肠杆菌的检出率极高。那么，其它谷物类食品是否同样存在阪崎肠杆菌污染？面粉（或其他谷物类）中存在的阪崎肠杆菌是否会在加工过程中污染室内环境，并进一步污染婴幼儿食品包括配方奶粉？本项目拟首先在谷物类食品中进行阪崎肠杆菌的检测，阐明阪崎肠杆菌在该类食品中的分布特征，掌握奶粉以外阪崎肠杆菌的可能传播宿主及天然储存场所；其次通过涂抹、搜集灰尘等采样方法，研究阪崎肠杆菌在谷物类食品生产加工场所及家庭环境中的污染特征；最后对分离到的阪崎肠杆菌进行分子分型和聚类分析，探讨阪崎肠杆菌潜在的传播途径，以期为制定该病原菌的防控策略提供理论依据。

Cronobacter spp. (formerly Enterobacter sakazakii) are an important group of emerging opportunistic foodborne pathogens that may cause rare but severe systemic infection such as neonatal meningitis, septicemia, and enterocolitis in neonates. Powdered infant formula (PIF) has been epidemiologically linked to the cases of infant infections. However, for several infection cases, no evidence has been found to conclude that the infant formula was contaminated during manufacturing or shipping. This begs several questions. Specially, how did these infants get infected, where did the contamination occur, and are there any possible transmission vehicles or natural reservoirs for the bacteria other than powdered infant formula? Indeed, these questions point to key gaps in the general knowledge about Cronobacter spp. biology. We found extremely high levels of Cronobacter spp. in wheat and related products. Then, how about the other kind of cereals? Since wheat flour (dust) can easily be disseminated through the air and settled onto other surfaces in food production facilities, will Cronobacter spp. in flour or other cereals contaminate indoor environment and then pollute the infant foods including PIF? In this study, we tried to seek and determine the critical and possible transmission vehicles and reservoirs other than infant formula for these opportunistic pathogenic bacteria. In addition, surveillance studies about Cronobacter spp. in various indoor environments of household and cereals food production facilities have also carried out. Furthermore, potential routes of transmission of Cronobacter were investigated based on pulsed field gel electrophoresis (PFGE) and the Multi Locus Sequence Typing (MLST) of bacteria isolations from both food and environment samples. Our study will contribute to strategies that might further decrease the risk of Cronobacter spp. infection.

阪崎肠杆菌是一种重要的食源性致病菌，可引起严重的新生儿脑膜炎，坏死性小肠结肠炎和菌血症等疾病。婴幼儿阪崎肠杆菌感染与配方奶粉密切相关，但污染的确切来源并不清楚。项目研究了谷物类食品中阪崎肠杆菌的分布特征，掌握了其可能的天然储存场所；研究了水稻和小麦各生长阶段阪崎肠杆菌分布特征，掌握了谷物类食品中阪崎肠杆菌的可能来源；研究了阪崎肠杆菌在谷物类食品生产加工场所及家庭环境的污染特征，并对分离到的菌株进行分子分型和聚类分析，探讨了其潜在的传播途径，并建议家有新生儿尤其是低体重新生儿的家庭减少面粉等谷物类粉的使用。主要结果如下：（1）采集551份常见谷物类进行阪崎肠杆菌检测，检出阳性样本193份，阳性率35.03%。①不同谷物类食品中均能检出阪崎肠杆菌，检出率随种类不同差异显著，其中荞麦类食品检出率最高，为51.61%，其次为薏米和小米，检出率分别为48.72%和48.15%；②检出率与加工过程息息相关，同一谷物来源的不同产品间检出率差异显著。 （2）127份样品的定量结果显示，谷物类样品中阪崎肠杆菌的浓度为0.3 MPN/100g ~>110MPN/100g，93.6%样品阪崎肠杆菌浓度<10 MPN/100g（平均4.33 MPN/100g），51.6%的样品阪崎肠杆菌浓度<1 MPN/100g（平均0.69 MPN/100g）。（3）水稻和小麦生长过程各阶段及生长环境中均能检出阪崎肠杆菌，PFGE结果证实水稻生长过程中携带的阪崎肠杆菌可能来源于其生长环境。（4）2家碾米厂和2家面粉加工厂室内涂抹样品中阪崎肠杆菌检出率分别为51.5 %，45.8 %，60.7 %和63.2 %，PFGE结果初步显示加工过程可能是产生阪崎肠杆菌交叉污染的重要原因。③速冻类食品中的阪崎肠杆菌检出率极高，PFGE结果表明生产线一旦遭受污染，会导致后续多个产品被污染。（5）采集了18个家庭共103份涂抹样品，检出阪崎肠杆菌阳性样本22份，阳性率为21.4%。分析显示家庭成员的饮食习惯对阪崎肠杆菌在家庭环境中的分布有明显影响，习惯吃面食的家庭环境中阪崎肠杆菌检出率更高。表明谷物类产品加工成粉状原材料后，后续的加工过程对于环境的污染存在潜在危险因素。