谷物类食品中阪崎肠杆菌分布特征及潜在传播途径研究

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。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。