U.S. Department of Agriculture, Agricultural Research Service, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, NE 68933-0166, USA.
J Food Prot. 2012 Aug;75(8):1418-28. doi: 10.4315/0362-028X.JFP-11-427.
Shiga toxin-producing Escherichia coli (STEC) strains are important foodborne pathogens. Among these, E. coli O157:H7 is the most frequently isolated STEC serotype responsible for foodborne diseases. However, the non-O157 serotypes have been associated with serious outbreaks and sporadic diseases as well. It has been shown that various STEC serotypes are capable of forming biofilms on different food or food contact surfaces that, when detached, may lead to cross-contamination. Bacterial cells at biofilm stage also are more tolerant to sanitizers compared with their planktonic counterparts, which makes STEC biofilms a serious food safety concern. In the present study, we evaluated the potency of biofilm formation by a variety of STEC strains from serotypes O157:H7, O26:H11, and O111:H8; we also compared biofilm tolerance with two types of common sanitizers, a quaternary ammonium chloride-based sanitizer and chlorine. Our results demonstrated that biofilm formation by various STEC serotypes on a polystyrene surface was highly strain-dependent, whereas the two non-O157 serotypes showed a higher potency of pellicle formation at air-liquid interfaces on a glass surface compared with serotype O157:H7. Significant reductions of viable biofilm cells were achieved with sanitizer treatments. STEC biofilm tolerance to sanitization was strain-dependent regardless of the serotypes. Curli expression appeared to play a critical role in STEC biofilm formation and tolerance to sanitizers. Our data indicated that multiple factors, including bacterial serotype and strain, surface materials, and other environmental conditions, could significantly affect STEC biofilm formation. The high potential for biofilm formation by various STEC serotypes, especially the strong potency of pellicle formation by the curli-positive non-O157 strains with high sanitization tolerance, might contribute to bacterial colonization on food contact surfaces, which may result in downstream product contamination.
产志贺毒素大肠杆菌（STEC）菌株是重要的食源性病原体。在这些菌株中，E. coli O157:H7 是最常分离到的 STEC 血清型，也是引起食源性疾病的主要致病菌。然而，非-O157 血清型也与严重的暴发和散发病例有关。已经表明，各种 STEC 血清型能够在不同的食物或食品接触表面形成生物膜，当这些生物膜脱落时，可能会导致交叉污染。与浮游状态的细菌细胞相比，处于生物膜状态的细菌细胞对消毒剂的耐受性更高，这使得 STEC 生物膜成为食品安全的一个严重问题。在本研究中，我们评估了来自 O157:H7、O26:H11 和 O111:H8 血清型的多种 STEC 菌株形成生物膜的能力；我们还比较了生物膜对两种常见消毒剂（一种季铵盐消毒剂和氯）的耐受性。我们的结果表明，各种 STEC 血清型在聚苯乙烯表面形成生物膜的能力高度依赖于菌株，而两种非-O157 血清型在玻璃表面气液界面形成菌膜的能力比 O157:H7 血清型更强。消毒剂处理显著减少了活的生物膜细胞数量。STEC 生物膜对消毒的耐受性取决于菌株，而与血清型无关。卷曲菌表达似乎在 STEC 生物膜形成和对消毒剂的耐受性中发挥了关键作用。我们的数据表明，包括细菌血清型和菌株、表面材料和其他环境条件在内的多种因素可能会显著影响 STEC 生物膜的形成。各种 STEC 血清型形成生物膜的潜力很大，尤其是卷曲菌阳性的非-O157 菌株具有很强的生物膜形成能力和对消毒剂的高耐受性，这可能导致细菌在食品接触表面定植，从而导致下游产品污染。
