Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2098 El-Manar II, Tunisia.
Area de Bioquímica y BiologíaMolecular, Universidad de La Rioja, Logroño, Spain.
Int J Antimicrob Agents. 2018 Dec;52(6):871-877. doi: 10.1016/j.ijantimicag.2018.06.002. Epub 2018 Jun 15.
Carbapenem resistance in Gram-negative bacteria constitutes a major clinical problem. We characterized molecular features among carbapenem-resistant Gram-negative clinical isolates collected from Southeastern Tunisian Island Hospital. Eighteen carbapenem-resistant clinical isolates (13 Klebsiella pneumoniae, 1 Proteus mirabilis, 1 Enterobacter cloacae, 3 Acinetobacter baumannii) were recovered during April 2015-August 2016. Molecular characterization of antimicrobial resistance was performed using polymerase chain reaction (PCR) and sequencing. Molecular typing of carbapenemase-producing K. pneumoniae was performed by pulsed-field gel electrophoresis (PFGE) after XbaI digestion and multilocus sequence typing (MLST). Conjugation experiments were conducted and type/number/size of plasmids were characterized by PCR-Based-Replicon-Typing and PFGE after S1 digestion. Carbapenemase genes were detected in K. pneumoniae [bla(8), bla+bla(1), bla(4)], P. mirabilis [bla(1)], E. cloacae [bla(1)] and A. baumannii [bla(3)]. K. pneumoniae isolates were typed as ST15, ST1412 and ST147 and showed seven different pulsotypes. The genetic structure surrounding bla was composed of ISAba125 and ble. The bla carried by E. cloacae was located within the variable region of a class1 integron and bla gene was inserted into Tn1999.2. IncA/C and IncFIIA replicons were implicated in dissemination of bla and a non-typeable 48.5 kb plasmid in the propagation of bla. The emergence of carbapenemase-producing Gram-negative species in a Tunisian hospital shows the need for preventive strategies and hygiene measures to minimize their spread. Although conjugative plasmids play an important role in rapid carbapenemase genes dissemination, other mobile genetic elements, such as insertion sequences, transposons and integrons, are involved in acquisition of these resistances.
革兰氏阴性细菌的碳青霉烯耐药性是一个主要的临床问题。我们对从突尼斯东南岛医院采集的碳青霉烯耐药革兰氏阴性临床分离株的分子特征进行了描述。在 2015 年 4 月至 2016 年 8 月期间，共分离出 18 株碳青霉烯耐药的临床分离株（13 株肺炎克雷伯菌、1 株奇异变形杆菌、1 株阴沟肠杆菌、3 株鲍曼不动杆菌）。采用聚合酶链反应（PCR）和测序法进行抗菌药物耐药性的分子特征分析。对产碳青霉烯酶肺炎克雷伯菌进行 XbaI 酶切后脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）进行分子分型。通过接合实验，S1 酶切后采用 PCR 复制子分型和 PFGE 对质粒的类型/数量/大小进行了特征分析。在肺炎克雷伯菌中检测到碳青霉烯酶基因 [bla(8)、bla+bla(1)、bla(4)]、奇异变形杆菌 [bla(1)]、阴沟肠杆菌 [bla(1)]和鲍曼不动杆菌 [bla(3)]。肺炎克雷伯菌分离株的型别为 ST15、ST1412 和 ST147，表现出 7 种不同的脉冲场凝胶电泳图谱。bla 周围的遗传结构由 ISAba125 和 ble 组成。阴沟肠杆菌携带的 bla 位于类 1 整合子的可变区，bla 基因插入到 Tn1999.2 中。IncA/C 和 IncFIIA 复制子参与了 bla 的传播，而一个无法分型的 48.5 kb 质粒在 bla 的传播中发挥了作用。碳青霉烯酶产生的革兰氏阴性菌在突尼斯医院的出现表明，需要采取预防策略和卫生措施来尽量减少其传播。尽管可接合质粒在碳青霉烯酶基因的快速传播中发挥了重要作用，但其他移动遗传元件，如插入序列、转座子和整合子，也参与了这些耐药性的获得。
