a Department of Medical Microbiology, Faculty of Medicine, Beykoz Institute of Life Sciences and Biotechnology, Bezmialem Vakif University , Istanbul , Turkey.
Infect Dis (Lond). 2019 Sep;51(9):676-682. doi: 10.1080/23744235.2019.1640386. Epub 2019 Jul 12.
Polymyxin B and colistin have similar structures except for one amino acid. Usually, physicians choose either polymyxin B or colistin for treatment of infections caused by multidrug-resistant (MDR) organisms. The preference is based on previous experience. Not much data are found in the literature comparing the two drugs against the same microorganisms. In this study, we compared antimicrobial activities of the two polymyxins against a panel of highly resistant and susceptible microorganisms. Eighty-nine clinical isolates (27 , 31 and 31 ) were tested in broth microdilution assays. Time-kill curve experiments were carried out on selected isolates. Significantly lower MICs for polymyxin B than for colistin were found against all species tested including ( .02), ( < .001) and ( < .01). The low MICs caused a change in categorical interpretations of only two and two . Similar results were obtained in time-kill curve experiments with both susceptible and resistant clinical isolates. Significantly lower MICs were found for polymyxin B against three of the most critical MDR species. Even though differences in categorical interpretations were not striking, lower MICs might be a critical consideration in clinical management of select cases where the concentration of these toxic antibiotics matters because of underlying co-morbidities. These results provide support to previous suggestions that re-consideration of breakpoint interpretations for polymyxins might be needed.
多黏菌素 B 和黏菌素的结构相似，仅差一个氨基酸。通常，医生会根据以往经验选择多黏菌素 B 或黏菌素来治疗多重耐药（MDR）病原体引起的感染。在本研究中，我们比较了两种多黏菌素对一组高度耐药和敏感微生物的抗菌活性。89 株临床分离株（27 株、31 株和 31 株）在肉汤微量稀释法中进行了检测。对选定的分离株进行了时间杀伤曲线实验。与所有测试的物种相比，多黏菌素 B 的 MIC 值均显著低于黏菌素，包括 （.02）、 （ < .001）和 （ <.01）。仅对两个 和两个 进行了分类解释的变化。在时间杀伤曲线实验中，对敏感和耐药的临床分离株也得到了相似的结果。多黏菌素 B 对三种最关键的 MDR 物种的 MIC 值显著降低。尽管分类解释的差异并不显著，但对于某些情况下，由于潜在的合并症，这些毒性抗生素的浓度很重要，因此较低的 MIC 值可能是临床管理的一个关键考虑因素。这些结果为先前的建议提供了支持，即可能需要重新考虑多黏菌素的断点解释。
