Instituto de Investigaciones Marinas (C.S.I.C.). Eduardo Cabello, 6. 36208 Vigo, (Pontevedra), Spain.
Food Microbiol. 2011 May;28(3):418-25. doi: 10.1016/j.fm.2010.09.014. Epub 2010 Oct 19.
Increase of resistance to the application of benzalkonium chloride (BAC), peracetic acid (PA) and nisin during biofilm formation at 25 °C by three strains of Listeria monocytogenes (CECT 911, CECT 4032, CECT 5873 and BAC-adapted CECT 5873) in different scenarios was compared. For this purpose, resistance after 4 and 11-days of biofilm formation was quantified in terms of lethal dose 90% values (LD(90)), determined according with a dose-response logistic mathematical model. Microscopic analyses after 4 and 11-days of L. monocytogenes biofilm formation were also carried out. Results demonstrated a relation between the microscopic structure and the resistance to the assayed biocides in matured biofilms. The worst cases being biofilms formed by the strain 4032 (in both stainless steel and polypropylene), which showed a complex "cloud-type" structure that correlates with the highest resistance of this strain against the three biocides during biofilm maturation. However, that increase in resistance and complexity appeared not to be dependent on initial bacterial adherence, thus indicating mature biofilms rather than planctonic cells or early-stage biofilms must be considered when disinfection protocols have to be optimized. PA seemed to be the most effective of the three disinfectants used for biofilms. We hypothesized both its high oxidizing capacity and low molecular size could suppose an advantage for its penetration inside the biofilm. We also demonstrated that organic material counteract with the biocides, thus indicating the importance of improving cleaning protocols. Finally, by comparing strains 5873 and 5873 adapted to BAC, several adaptative cross-responses between BAC and nisin or peracetic acid were identified.
在 25°C 下，通过比较三种李斯特菌（CECT 911、CECT 4032、CECT 5873 和适应苯扎氯铵的 CECT 5873）在不同情况下形成生物膜时对苯扎氯铵（BAC）、过氧乙酸（PA）和乳链菌肽（nisin）的应用阻力的增加，定量评估了 4 天和 11 天后生物膜形成时的致死剂量 90%值（LD(90)）。根据剂量-反应逻辑数学模型进行了测定。还对李斯特菌生物膜形成 4 天和 11 天后进行了微观分析。结果表明，在成熟生物膜中，微观结构与抗杀生物剂之间存在一定的关系。最糟糕的情况是由 4032 菌株形成的生物膜（在不锈钢和聚丙烯上），其表现出复杂的“云状”结构，这与该菌株在生物膜成熟过程中对三种杀生物剂的最高抗性相关。然而，这种抗性和复杂性的增加似乎并不依赖于初始细菌的附着，这表明在优化消毒方案时，必须考虑成熟的生物膜，而不是浮游细胞或早期生物膜。PA 似乎是三种消毒剂中用于生物膜的最有效消毒剂。我们假设其高氧化能力和低分子量可能使其具有渗透到生物膜内部的优势。我们还证明了有机物质会与杀生物剂相互作用，这表明改进清洁方案的重要性。最后，通过比较适应苯扎氯铵的 5873 菌株和 5873 菌株，我们确定了苯扎氯铵和乳链菌肽或过氧乙酸之间存在几种适应性交叉反应。
