Flagella mediate attachment of enterotoxigenic Escherichia coli to fresh salad leaves.
Flagella mediate attachment of enterotoxigenic Escherichia coli to fresh salad leaves.
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DOI：
10.1111/j.1758-2229.2010.00195.x
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发表时间：
2011-02
影响因子：
3.3
通讯作者：
R. Shaw;C. Berger;M. Pallen;Å. Sjöling;G. Frankel
中科院分区：
文献类型：
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作者：
R. Shaw;C. Berger;M. Pallen;Å. Sjöling;G. Frankel
产肠毒素大肠杆菌(ETEC)会导致儿童和旅行者腹泻，并被认为是通过水和食物传播的。据追踪，零星暴发是由于食用了受污染的新鲜农产品，特别是生菜和欧芹等沙拉叶。重要的是，ETEC结合沙拉叶的机制尚不清楚。在这项研究中，我们调查了ETEC临床分离株对Eruca vesicaria(俗称Rocket)的黏附能力。为此，我们用生长在Luria肉汤中的临床ETEC分离株在20°C的Luria肉汤中接种切下的泡囊E.vesicaria叶片，这种条件不允许表达质粒编码的定植因子，因此模拟了ETEC通过摄入受污染食物的实际传播途径。我们发现ETEC菌株以不同的效率结合泡囊肠杆菌。对典型菌株的扫描电子显微镜观察表明，它们以类似鞭毛的延伸细丝以扩散的方式附着在泡囊棘球绦虫的表面。利用ETEC的原型菌株H10407，我们发现它也能与生菜、罗勒和菠菜的叶片结合。H10407的结合依赖于鞭毛，因为它是一个附着在叶片上的flc突变体，其结合效率要低得多。有趣的是，在所使用的环境条件下，形成鞭毛顶端结构的EtpA和定植因子I对于叶片附着是必不可少的。结果表明，ETEC可以与沙拉叶特异结合，这可能是一个重要的、但鲜为人知的感染源。
Enterotoxigenic Escherichia coli (ETEC) causes child and travelers' diarrhea and is presumed to be water- and food-borne. Sporadic outbreaks were traced to consumption of contaminated fresh produce, particularly salad leaves as lettuce and parsley. Importantly, the mechanism by which ETEC binds salad leaves is not known. In this study we investigated the ability of clinical ETEC isolates to adhere to Eruca vesicaria (commonly known as rocket). Towards this end we inoculated pieces of cut E. vesicaria leaves with clinical ETEC isolates grown in Luria broth at 20°C, conditions that are not permissive for expression of the plasmid-encoded colonization factors and hence mimic the actual transmission pathways of ETEC through intake of contaminated food. We found that ETEC strains bind E. vesicaria at various efficiencies. Examination of representative strains by scanning electron microscopy revealed that they adhere to the E. vesicaria surface in a diffuse pattern by extended filaments resembling flagella. Using the prototype ETEC strain H10407 we found that it also binds to lettuce, basil and spinach leaves. Binding of H10407 was dependent on flagella as a fliC mutant attached to leaves at a much lower efficiency. Interestingly, under the employed environmental conditions EtpA, which forms a flagellar tip structure, and colonization factor I are dispensable for leaf attachment. The results show that ETEC can bind specifically to salad leaves, which might represent an important, yet less recognized, source of infection.