School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA
Appl Environ Microbiol. 2018 May 31;84(12). doi: 10.1128/AEM.00197-18. Print 2018 Jun 15.
Benzalkonium chlorides (BAC) are commonly used biocides in broad-spectrum disinfectant solutions. How microorganisms cope with BAC exposure remains poorly understood, despite its importance for disinfection and disinfectant-induced antibiotic resistance. To provide insights into these issues, we exposed two isolates of an opportunistic pathogen, , to increasing concentrations of BAC. One isolate was preadapted to BAC, as it originated from a bioreactor fed with subinhibitory concentrations of BAC for 3 years, while the other originated from a bioreactor that received no BAC. Replicated populations of both isolates were able to survive high concentrations of BAC, up to 1,200 and 1,600 mg/liter for the non- and preadapted strains, respectively, exceeding typical application doses. Transcriptome sequencing (RNA-seq) analysis revealed upregulation of efflux pump genes and decreased expression of porins related to BAC transport as well as reduced growth rate. Increased expression of spermidine (a polycation) synthase genes and mutations in the (polymyxin resistance) gene, which cause a reduction in membrane negative charge, suggested that a major adaptation to exposure to the cationic surfactant BAC was to actively stabilize cell surface charge. Collectively, these results revealed that adapts to BAC exposure by a combination of mechanisms and provided genetic markers to monitor BAC-resistant organisms that may have applications in the practice of disinfection. BAC are widely used as biocides in disinfectant solutions, food-processing lines, domestic households, and health care facilities. Due to their wide use and mode of action, there has been rising concern that BAC may promote antibiotic resistance. Consistent with this idea, at least 40 outbreaks have been attributed to infection by disinfectant- and antibiotic-resistant pathogens such as However, the underlying molecular mechanisms that bacteria use to deal with BAC exposure remain poorly elucidated. Elucidating these mechanisms may be important for monitoring and limiting the spread of disinfectant-resistant pathogens. Using an integrated approach that combined genomics and transcriptomics with physiological characterization of BAC-adapted isolates, this study provided a comprehensive understanding of the BAC resistance mechanisms in Our findings also revealed potential genetic markers to detect and monitor the abundance of BAC-resistant pathogens across clinical or environmental settings. This work contributes new knowledge about high concentrations of benzalkonium chlorides disinfectants-resistance mechanisms at the whole-cell genomic and transcriptomic level.
苯扎氯铵（BAC）是广谱消毒剂中常用的杀菌剂。尽管 BAC 对消毒和消毒剂诱导的抗生素耐药性很重要，但微生物如何应对 BAC 暴露仍知之甚少。为了深入了解这些问题，我们将两种机会性病原体的分离株暴露于不断增加的 BAC 浓度下。一种分离株对 BAC 进行了预先适应，因为它来自于经过 3 年亚抑菌浓度 BAC 喂养的生物反应器，而另一种分离株则来自于未接受 BAC 的生物反应器。两种分离株的复制种群均能够在高浓度的 BAC 下存活，未适应和预先适应的菌株分别高达 1200 和 1600mg/L，超过了典型的应用剂量。转录组测序（RNA-seq）分析显示，外排泵基因上调，与 BAC 转运相关的孔蛋白表达减少，生长速度降低。多胺（多阳离子）合酶基因表达增加和 （多粘菌素耐药）基因的突变导致膜负电荷减少，表明对阳离子表面活性剂 BAC 的主要适应是主动稳定细胞表面电荷。总的来说，这些结果表明， 通过多种机制适应 BAC 暴露，并提供了遗传标记来监测可能在消毒实践中应用的 BAC 抗性生物。BAC 作为杀菌剂广泛应用于消毒剂溶液、食品加工线、家庭和医疗机构。由于其广泛的用途和作用模式，人们越来越担心 BAC 可能会促进抗生素耐药性。至少有 40 起暴发归因于消毒剂和抗生素耐药病原体（如 ）感染，这与这种观点一致。然而，细菌用于应对 BAC 暴露的潜在分子机制仍未得到充分阐明。阐明这些机制对于监测和限制消毒剂耐药病原体的传播可能很重要。本研究采用基因组学和转录组学与 BAC 适应分离株生理特性相结合的综合方法，全面了解了 中 BAC 耐药的机制。我们的研究结果还揭示了潜在的遗传标记，可用于检测和监测临床或环境环境中 BAC 耐药病原体的丰度。这项工作为在全细胞基因组和转录组水平上了解高浓度苯扎氯铵消毒剂的耐药机制提供了新的知识。
