Brözel V S, Cloete T E
Department of Microbiology and Plant Pathology, University of Pretoria, South Africa.
J Appl Bacteriol. 1994 Jun;76(6):576-82. doi: 10.1111/j.1365-2672.1994.tb01655.x.
This investigation was to determine whether Pseudomonas aeruginosa could acquire resistance to the bactericide isothiazolone, and what the nature of such a resistance mechanism would be. The Pseudomonas was cultured in nutrient-limited broth in the presence of sub-inhibitory concentrations of isothiazolone (a mixture of 1.15% 5-chloro-N-methylisothiazolone (CMIT) and 0.35% N-methylisothiazolone (MIT)). Three cultures tested in parallel adapted gradually during exposure for 15 d from an initial minimum inhibitory concentration (MIC) of 300 microliters l-1 to 607 microliters l-1. The three parallel cultures adapted at similar rates, so the adaptation was not ascribed to mutation but to a specific mechanism. Resistant cells did not produce any extracellular isothiazolone-quenching compounds nor undergo detectable alterations in their lipopolysaccharide layer. In wild cells, a 35 kDa outer membrane protein (protein T) was detectable, whereas resistant cells lacked this protein. Production of protein T was suppressed within 24 h of exposure to isothiazolone. It was still suppressed after 72 h of growth in isothiazolone-free medium. It is proposed that Ps. aeruginosa acquires resistance to isothiazolone by a process of adaptation where the outer membrane protein T is suppressed.
本研究旨在确定铜绿假单胞菌是否能够获得对杀菌剂异噻唑啉酮的抗性，以及这种抗性机制的本质是什么。将假单胞菌在营养受限的肉汤中培养，同时存在亚抑制浓度的异噻唑啉酮（1.15% 5-氯-N-甲基异噻唑啉酮（CMIT）和0.35% N-甲基异噻唑啉酮（MIT）的混合物）。在暴露15天的过程中，平行测试的三种培养物逐渐适应，初始最低抑菌浓度（MIC）为300微升/升，最终达到607微升/升。三种平行培养物以相似的速率适应，因此这种适应不是归因于突变，而是归因于一种特定机制。抗性细胞不产生任何细胞外异噻唑啉酮淬灭化合物，其脂多糖层也未发生可检测到的变化。在野生型细胞中，可检测到一种35 kDa的外膜蛋白（蛋白T），而抗性细胞缺乏这种蛋白。暴露于异噻唑啉酮24小时内，蛋白T的产生受到抑制。在无异噻唑啉酮的培养基中生长72小时后，其仍受到抑制。有人提出，铜绿假单胞菌通过外膜蛋白T受到抑制的适应过程获得对异噻唑啉酮的抗性。
