Faculty of Medicine and Life Sciences, Hasselt University, 3500 Hasselt, Belgium.; Department of Infectious Diseases and Immunity, Jessa Hospital, 3500 Hasselt, Belgium; Department of Internal Medicine and Center for Infectious Diseases, Radboud University Medical Center, 6663 Nijmegen, The Netherlands.
AIT, Austrian Institute for Technology, 1210 Vienna, Austria.
Infect Genet Evol. 2020 Jul;81:104263. doi: 10.1016/j.meegid.2020.104263. Epub 2020 Feb 24.
Colistin is a last-resort antibiotic for the treatment of infections caused by multidrug and carbapenem-resistant Gram-negative bacteria. Colistin resistance has been emerging and multiple outbreaks have been reported in Europe and elsewhere. It has been most frequently reported in carbapenem-resistant K. pneumoniae. In this study, 24 multidrug and colistin-resistant clinical isolates (14 K. pneumoniae, one E. aerogenes, one E. cloacae, and eight A. baumannii) were collected from four hospitals in Croatia from 2013 to 2018, in order to analyse the molecular epidemiology and mechanisms of antibiotic resistance. β-lactamase and carbapenemase genes were detected by PCR. Genotyping was done on selected isolates by rep-PCR. Whole genome sequencing (WGS) was performed to discover possible molecular mechanisms for the observed colistin resistance. All isolates, except two K. pneumoniae isolates, were extensively drug resistant. Ten out of 16 (63%) K. pneumoniae isolates possessed bla which is the most common carbapenem resistance gene in Croatia and in other parts of Europe. All A. baumannii isolates possessed the OXA-23-like carbapenem hydrolysing oxacillinase and five turned out to be pandrug-resistant. Colistin resistance was most likely chromosomally mediated. After sequence analysis, none of the isolates were found to possess any of the mcr gene variants. Several previously reported mutations were found in PmrB, PhoP, PhoQ, and MgrB, which are associated with colistin resistance. In the global phylogenetic analysis, DNA mutations causing mutations in the MgrB protein were present mostly in lineages comprising colistin resistant isolates, and the second most prevalent mutation (K3X) was also encountered in our isolates. In addition, based on genotyping by rep-PCR, the spread of colistin resistance is most likely to be clonal. Most importantly, the presence of colistin resistance together with carbapenemase genes in extensively drug resistant isolates poses real threats in the use of carbapenems and colistin to fight infections.
黏菌素是治疗多重耐药和碳青霉烯类耐药革兰氏阴性菌感染的最后手段抗生素。黏菌素耐药性已经出现，并且在欧洲和其他地方已经报告了多起暴发事件。它最常报告于耐碳青霉烯类的肺炎克雷伯菌。在这项研究中，从 2013 年至 2018 年，从克罗地亚的四家医院收集了 24 株多药和黏菌素耐药的临床分离株（14 株肺炎克雷伯菌、1 株产气肠杆菌、1 株阴沟肠杆菌和 8 株鲍曼不动杆菌），以分析分子流行病学和抗生素耐药机制。通过 PCR 检测β-内酰胺酶和碳青霉烯酶基因。选择分离株进行重复聚合酶链反应（rep-PCR）进行基因分型。对全基因组测序（WGS）进行了分析，以发现观察到的黏菌素耐药的可能分子机制。除了两株肺炎克雷伯菌分离株外，所有分离株均为广泛耐药。16 株肺炎克雷伯菌中有 10 株（63%）携带 bla，这是克罗地亚和欧洲其他地区最常见的碳青霉烯类耐药基因。所有鲍曼不动杆菌分离株均携带 OXA-23 样碳青霉烯水解的β-内酰胺酶，其中 5 株为泛耐药。黏菌素耐药很可能是由染色体介导的。经过序列分析，未发现任何分离株携带任何 mcr 基因变体。在 PmrB、PhoP、PhoQ 和 MgrB 中发现了几个先前报道的突变，这些突变与黏菌素耐药有关。在全球系统发育分析中，导致 MgrB 蛋白突变的 DNA 突变主要存在于包含黏菌素耐药分离株的谱系中，而我们分离株中也存在第二常见的突变（K3X）。此外，根据 rep-PCR 基因分型，黏菌素耐药的传播很可能是克隆性的。最重要的是，广泛耐药分离株中黏菌素耐药与碳青霉烯酶基因的存在对碳青霉烯类和黏菌素治疗感染构成了真正的威胁。
