Due to the strong pathogenicity of hypervirulent Klebsiella pneumoniae (hvKP), its performance against disinfectants in water should be understood to protect public health and ecological environment. Unfortunately, the disinfectant tolerance of hvKP with a hypermucoviscosity (HMV) phenotype is a critical underexplored area. Here, the tolerance of K. pneumoniae isolates to common disinfectants was evaluated, and its underlying mechanisms were clarified. Results showed that hvKP strains with HMV exhibited remarkable tolerance to triclosan (TCS), sodium hypochlorite (NaClO), and benzalkonium bromide (BB), surpassing that of low-virulent K. pneumoniae (lvKP) and Escherichia coli, which is the microbial indicator of drinking water quality. Ct value of NaClO reached 4.41 mg/L·min to kill 4-log hvKP, while the values were 2.52 and 2.28 mg/L·min to achieve 4-log killing of lvKP and E. coli, respectively. The curing of the virulence plasmid from hvKP strain K2044 revealed that capsular polysaccharide (CPS) synthesis, driven by the virulence plasmids, helped mitigate cell membrane injury and bacterial inactivation under NaClO stress; consequently, it provided a protective advantage to hvKP. Enhancing the antioxidative stress system to reduce ROS production and mitigate oxidative stress caused by NaClO further improved the disinfectant resistance of hvKP strains with HMV. This study emphasized that hvKP strains with HMV posed a considerable challenge to disinfection procedure of water treatment. It also revealed that an improved dosage of NaClO ensures bacteria killing, indicating the optimization of the design of water treatment processes involving disinfection strategies and technical parameters should be considered.

中文翻译：

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具有高粘液粘度表型的高毒力肺炎克雷伯菌对其荚膜多糖的水消毒策略提出了挑战


由于高毒力肺炎克雷伯菌 （hvKP） 具有很强的致病性，应了解其对水中消毒剂的性能，以保护公众健康和生态环境。不幸的是，具有高粘液粘度 （HMV） 表型 的 hvKP 的消毒剂耐受性是一个关键的未被充分开发的领域。在这里，评估了肺炎克雷伯菌分离株对常见消毒剂的耐受性，并阐明了其潜在机制。结果表明，含有 HMV 的 hvKP 菌株对三氯生 （TCS） 、次氯酸钠 （NaClO） 和苯扎溴铵 （BB） 表现出显著的耐受性，超过了低毒力肺炎克雷伯菌 （lvKP） 和大肠杆菌，后者是饮用水质量的微生物指标。NaClO 的 Ct 值达到 4.41 mg/L·min 杀死 4 对数的 hvKP，而 2.52 和 2.28 mg/L·min 分别实现 4 对数杀死 lvKP 和大肠杆菌。hvKP 菌株 K2044 毒力质粒的固化表明，由毒力质粒驱动的荚膜多糖 （CPS） 合成有助于减轻 NaClO 胁迫下的细胞膜损伤和细菌失活;因此，它为 hvKP 提供了保护优势。增强抗氧化应激系统以减少 ROS 产生并减轻 NaClO 引起的氧化应激，进一步提高了 hvKP 菌株对 HMV 的消毒剂耐受性。本研究强调 HMV 的 hvKP 菌株对水处理的消毒程序构成了相当大的挑战。研究还表明，提高 NaClO 的剂量可确保杀死细菌，表明应考虑优化涉及消毒策略和技术参数的水处理工艺设计。