Underlying mechanisms of carbapenem resistance in extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Escherichia coli isolates at a tertiary care centre in Lebanon: role of OXA-48 and NDM-1 carbapenemases
Underlying mechanisms of carbapenem resistance in extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Escherichia coli isolates at a tertiary care centre in Lebanon: role of OXA-48 and NDM-1 carbapenemases
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DOI：
10.1016/j.ijantimicag.2012.08.010
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发表时间：
2013-01-01
影响因子：
10.8
通讯作者：
Matar, G. M.
中科院分区：
文献类型：
--
作者：
Baroud, M.;Dandache, I.;Matar, G. M.
最近在黎巴嫩的一个主要三级保健中心，产广谱β -内酰胺酶（ESBL）的肺炎克雷伯菌和大肠埃希菌分离株中碳青霉烯类耐药性的增加促使了这项研究的开始。对连续产esbls的分离株进行碳青霉烯类耐药试验，采用纸片扩散法进行初步筛选，用厄他培南进行试验。并进行了改进的Hodge检验。PCR检测β -内酰胺酶编码基因bla（NDM-1）、bla（KPC）、bla（OXA-48）、bla（CTX-M）、bla（TEM）、bla（SHV）、bla（CMY-2）和bla（OXA-1）以及外膜孔蛋白基因ompC和ompF。测序、外排泵抑制剂检测和随机扩增多态性DNA （RAPD）分析。572株肺炎克雷伯菌中有14株（2.45%）和2243株大肠杆菌中有24株（1.07%）对埃他培宁不敏感[最低抑菌浓度(MIC) >= 0.25 μ g/mL]。对其他碳青霉烯类的抗性是可变的。PCR和测序结果显示，分离株含有不同的β -内酰胺酶基因，分别为bla（OXA-1）、bla（CTX-M-15）、bla（TEM-1）、bla（CMY-2）、bla（OXA-48）和bla（NDM-1）。此外，肺炎克雷伯菌缺乏外膜孔蛋白编码基因，而大肠杆菌则携带了检测到的突变基因。CTX-M-15在90kb质粒上携带，OXA-48在70kb质粒上携带。外排泵抑制显著降低大肠杆菌的mic。RAPD分析显示了基因组变异性。综上所述，产esbl的肺炎克雷伯菌和大肠杆菌对碳青霉烯烯的耐药性是由于在这些生物中观察到的具有孔蛋白不渗透性和/或外排泵活性的β -内酰胺酶的联合作用，并且在许多分离株中是由于产生了编码碳青霉烯烯酶的基因bla（OXA-48）和新出现的bla（nmm -1）。(C) 2012 Elsevier B.V.与International Society of Chemotherapy。版权所有。
A recent increase in carbapenem resistance among extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae and Escherichia coli isolates at a major tertiary care centre in Lebanon prompted the initiation of this study. Consecutive ESBL-producing isolates were tested for resistance to carbapenems, with initial screening by disk diffusion and Etest using ertapenem. The modified Hodge test was also performed. PCR of beta-lactamase-encoding genes, including bla(NDM-1), bla(KPC), bla(OXA-48), bla(CTX-M), bla(TEM), bla(SHV), bla(CMY-2) and bla(OXA-1), as well as outer membrane porin genes (ompC and ompF) was performed. Sequencing, efflux pump inhibitor tests and random amplified polymorphic DNA (RAPD) analysis were performed. In total, 14 (2.45%) of 572 K. pneumoniae and 24 (1.07%) of 2243 E. coli were ertapenem-non-susceptible [minimum inhibitory concentration (MIC) >= 0.25 mu g/mL]. Resistance to other carbapenems was variable. PCR and sequencing analysis revealed that isolates harboured different beta-lactamase genes, including bla(OXA-1), bla(CTX-M-15), bla(TEM-1), bla(CMY-2), bla(OXA-48) and bla(NDM-1). In addition, K. pneumoniae lacked the outer membrane porin-encoding genes, whilst E. coli harboured them with detected mutations. CTX-M-15 was carried on a 90 kb plasmid, whilst OXA-48 was carried on a 70 kb plasmid. Efflux pump inhibition significantly decreased MICs in E. coli. RAPD analysis demonstrated genomic variability. In conclusion, carbapenem resistance in ESBL-producing K. pneumoniae and E. coli is due to the combined effect of beta-lactamases with porin impermeability and/or efflux pump activity observed in these organisms, and in a number of isolates is due to the production of the carbapenemase-encoding genes bla(OXA-48) and the newly emerging bla(NDM-1). (C) 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.