Ouertani Rym, Ben Jomàa-Jemili Mariem, Gharsa Haythem, Limelette Anne, Guillard Thomas, Brasme Lucien, de Champs Christophe, Chouchani Chedly
1 Faculté des Sciences de Bizerte, Université de Carthage , Jarzouna, Tunisie.
2 Laboratoire de Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université de Tunis El-Manar , El-Manar II, Tunisie.
Microb Drug Resist. 2018 Mar;24(2):142-149. doi: 10.1089/mdr.2016.0236. Epub 2017 Jul 24.
Carbapenemase-producing Klebsiella pneumoniae strains have emerged as a major problem for healthcare systems. The aim of this study was to determine the role and diversity of plasmids harboring carbapenemases encoding genes from a collection of K. pneumoniae isolates recovered between July 2011 and January 2012, with decreased susceptibility to carbapenems. Imipenem (IPM), ertapenem (ETP), meropenem (MEM), and doripenem (DOR) minimum inhibitory concentrations (MICs) were determined by E-test. Carbapenemase production was detected with the modified Hodge test. β-Lactamases encoding genes were amplified by PCR and sequenced. Plasmid incompatibility groups harbored by carbapenemases producers were investigated using the PCR-based replicon typing method and the clonal relationship of the isolates was investigated by pulse filed electrophoresis. IMP, ertapenem, meropenem, and doripenem MICs ranged between 0.25 and 16 mg/L. Carbapenemase activity was detected in 14 isolates. Two carbapenemases were identified: OXA-48 in 13 isolates and a new variant OXA-204 in 1 isolate, in combination with extended-spectrum β-lactamases, CTX-M-1, CTX-M-9, CTX-M-14, CTX-M-15, and VEB-8. One isolate produced CMY-2. OXA-48 and the new variant OXA-204 were confirmed as transferable plasmid encoded. The carbapenemase-producing K. pneumoniae harbored plasmids of the A/C, LVPK, and L/M replicon types. Thirteen different pulso types were observed. Three pairs of isolates showed a clonal relatedness. This diversity in β-lactamases, in pulso types and in plasmid content, shows the ability of OXA-type carbapenemase to disseminate. This is worrying for the control of the increase in antibiotic resistance frequency and necessitates that continuous investigations in the clinical setting remain a high priority to clarify the contribution of antimicrobial use into multiresistance bacterial dissemination.
产碳青霉烯酶肺炎克雷伯菌菌株已成为医疗系统面临的一个主要问题。本研究的目的是确定2011年7月至2012年1月间收集的对碳青霉烯类药物敏感性降低的肺炎克雷伯菌分离株中携带碳青霉烯酶编码基因的质粒的作用和多样性。采用E-test法测定亚胺培南（IPM）、厄他培南（ETP）、美罗培南（MEM）和多利培南（DOR）的最低抑菌浓度（MIC）。采用改良Hodge试验检测碳青霉烯酶的产生。通过PCR扩增并测序β-内酰胺酶编码基因。采用基于PCR的复制子分型方法研究产碳青霉烯酶菌株携带的质粒不相容群，并通过脉冲场电泳研究分离株的克隆关系。IPM、厄他培南、美罗培南和多利培南的MIC范围为0.25至16mg/L。在14株分离株中检测到碳青霉烯酶活性。鉴定出两种碳青霉烯酶：13株分离株中为OXA-48，1株分离株中为新变体OXA-204，同时伴有超广谱β-内酰胺酶CTX-M-1、CTX-M-9、CTX-M-14、CTX-M-15和VEB-8。1株分离株产生CMY-2。OXA-48和新变体OXA-204被确认为可转移的质粒编码。产碳青霉烯酶的肺炎克雷伯菌携带A/C、LVPK和L/M复制子类型的质粒。观察到13种不同的脉冲型。三对分离株显示出克隆相关性。β-内酰胺酶、脉冲型和质粒含量的这种多样性表明OXA型碳青霉烯酶具有传播能力。这对抗生素耐药频率增加的控制令人担忧，并且有必要将临床环境中的持续调查作为高度优先事项，以阐明抗菌药物使用对多重耐药细菌传播的影响。
