Department of Clinical Microbiology, Christian Medical College, Vellore 632004, Tamil Nadu, India.
Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA.
J Glob Antimicrob Resist. 2018 Mar;12:124-136. doi: 10.1016/j.jgar.2017.09.011. Epub 2017 Sep 28.
Emerging multidrug-resistant (MDR) nosocomial pathogens are a great threat. Polymyxins, an old class of cationic polypeptide antibiotic, are considered as last-resort drugs in treating infections caused by MDR Gram-negative bacteria. Increased use of polymyxins in treating critically ill patients necessitates routine polymyxin susceptibility testing. However, susceptibility testing both of colistin and polymyxin B (PMB) is challenging. In this review, currently available susceptibility testing methods are briefly discussed. The multicomponent composition of colistin and PMB significantly influences susceptibility testing. In addition, poor diffusion in the agar medium, adsorption to microtitre plates and the synergistic effect of the surfactant polysorbate 80 with polymyxins have a great impact on the performance of susceptibility testing methods This review also describes recently identified chromosomal resistance mechanisms, including modification of lipopolysaccharide (LPS) with 4-amino-4-deoxy-l-arabinose (L-Ara4-N) and phosphoethanolamine (pEtN) resulting in alteration of the negative charge, as well as the plasmid-mediated colistin resistance determinants mcr-1, mcr-1.2, mcr-2 and mcr-3.
新兴的多药耐药（MDR）医院获得性病原体是一个巨大的威胁。多粘菌素，一种古老的阳离子多肽抗生素，被认为是治疗多药耐药革兰氏阴性菌感染的最后手段药物。在治疗重症患者时越来越多地使用多粘菌素，这就需要常规进行多粘菌素药敏试验。然而，多粘菌素和多粘菌素 B（PMB）的药敏试验具有挑战性。在这篇综述中，简要讨论了目前可用的药敏试验方法。多粘菌素和 PMB 的多组分组成对药敏试验有显著影响。此外，在琼脂培养基中的扩散不良、吸附到微量滴定板以及吐温 80 与多粘菌素的协同作用对药敏试验方法的性能有很大影响。本文还描述了最近发现的染色体耐药机制，包括通过 4-氨基-4-去氧-l-阿拉伯糖（L-Ara4-N）和磷酸乙醇胺（pEtN）修饰脂多糖（LPS），导致负电荷改变，以及质粒介导的多粘菌素耐药决定因子 mcr-1、mcr-1.2、mcr-2 和 mcr-3。
