Department for Nephrology, General Hospital Pula, Pula, Croatia.
Department for Microbiology, School of Medicine, University of Zagreb, Zagreb, Croatia; Clinical Department for Clinical and Molecular Microbiology, University Hospital Center Zagreb, Zagreb, Croatia.
J Glob Antimicrob Resist. 2017 Sep;10:213-218. doi: 10.1016/j.jgar.2017.07.001. Epub 2017 Jul 19.
During routine diagnostic laboratory work, the clinical microbiologist observed an increase of Acinetobacter baumannii isolates with three different carbapenem susceptibility patterns: susceptible, intermediate and resistant. Isolates belonging to the same carbapenem susceptibility phenotype exhibited identical susceptibility/resistance patterns to non-β-lactam antibiotics. This prompted us to analyse the mechanisms of carbapenem-resistance and the molecular epidemiology of the isolates. A total of 59 A. baumannii isolates were analysed and grouped according to their susceptibility to imipenem: group 1 were susceptible (N=24), group 2 were intermediate (N=8) and group 3 were resistant (N=27) to imipenem.
PCR and sequencing was used to detect resistance genes. Genotyping of the isolates was performed by PFGE and MLST.
Out of 27 resistant isolates, 20 harboured bla and 7 bla genes. ISAba1 was found upstream of bla and bla genes. PFGE genotyping demonstrated the existence of three major A. baumannii clones in GH Pula and determination of sequence groups showed that the isolates belonged to international clones commonly associated with multidrug-resistance. MLST (performed on six isolates) showed diverse population structure of isolates belonging to the same cluster, including ST 195, ST 231, ST 775 and ST 1095.
A previous study conducted in 2009-2010 showed that reduced susceptibility to carbapenems in GH Pula was only associated with upregulation of the intrinsic OXA-51 β-lactamase. In this study a shift to isolates with acquired oxacillinases, belonging to two major clones was reported.
在常规诊断实验室工作中，临床微生物学家观察到具有三种不同碳青霉烯类药物敏感性模式的鲍曼不动杆菌分离株增加：敏感、中介和耐药。属于相同碳青霉烯类药物敏感性表型的分离株对非β-内酰胺类抗生素表现出相同的敏感性/耐药性模式。这促使我们分析碳青霉烯类耐药的机制和分离株的分子流行病学。总共分析了 59 株鲍曼不动杆菌分离株，并根据其对亚胺培南的敏感性进行分组：组 1 为敏感（N=24），组 2 为中介（N=8），组 3 为耐药（N=27）。
使用 PCR 和测序检测耐药基因。通过 PFGE 和 MLST 对分离株进行基因分型。
在 27 株耐药分离株中，20 株携带 bla 和 7 株 bla 基因。ISAba1 位于 bla 和 bla 基因上游。PFGE 基因分型显示 GH Pula 存在三种主要的鲍曼不动杆菌克隆，序列组确定表明分离株属于与多药耐药相关的国际克隆。MLST（对 6 株分离株进行）显示同一簇内分离株的种群结构多样，包括 ST 195、ST 231、ST 775 和 ST 1095。
之前在 2009-2010 年进行的一项研究表明，GH Pula 对碳青霉烯类药物的敏感性降低仅与固有 OXA-51 内酰胺酶的上调有关。在这项研究中，报告了两种主要克隆中携带获得性 oxacillinases 的分离株的转变。
