Mohanty Srujana, Gajanand Mittal, Gaind Rajni
Department of Microbiology, VMMC and Safdarjung Hospital, New Delhi, India.
Indian J Med Microbiol. 2017 Jul-Sep;35(3):421-425. doi: 10.4103/ijmm.IJMM_16_386.
Acquired resistance in carbapenem-resistant Enterobacteriaceae (CRE) conferred by carbapenemases is a major concern worldwide. Consecutive, non-duplicate isolates of Escherichia coli (EC) and Klebsiella pneumoniae from clinically diagnosed bloodstream infections were screened for the presence of carbapenem resistance by standard disk-diffusion method and minimum inhibitory concentration breakpoints using the Clinical and Laboratory Standards Institute guidelines. Carbapenemase-encoding genes were amplified by polymerase chain reaction. Of 387 isolates (214 K. pneumoniae, 173 EC) tested, 93 (24.03%) were found to be CRE. Of these, 71 (76.3%) were positive for at least one tested carbapenemase gene. The frequency of carbapenemase genes was New Delhi metallo-β-lactamse-1 (65.6%), oxacillinase (OXA)-48 (24.7%), OXA-181 (23.6%), Verona integron-encoded metallo-β-lactamase (6.4%) and K. pneumoniae carbapenemase (2.1%). Our study identified presence of carbapenemases in a large proportion of CRE isolates. Delineation of resistance mechanisms is important in view of future therapeutics concerned with the treatment of CRE and for aiding control efforts by surveillance and infection control interventions.
由碳青霉烯酶介导的耐碳青霉烯肠杆菌科细菌（CRE）获得性耐药是全球范围内的一个主要问题。采用标准纸片扩散法和最低抑菌浓度断点，按照临床和实验室标准协会指南，对临床诊断的血流感染中连续、非重复的大肠杆菌（EC）和肺炎克雷伯菌分离株进行碳青霉烯耐药性筛查。通过聚合酶链反应扩增碳青霉烯酶编码基因。在检测的387株分离株（214株肺炎克雷伯菌、173株EC）中，发现93株（24.03%）为CRE。其中，71株（76.3%）至少一种检测的碳青霉烯酶基因呈阳性。碳青霉烯酶基因的频率依次为：新德里金属β-内酰胺酶-1（65.6%）、氧青霉烯酶（OXA）-48（24.7%）、OXA-181（23.6%）、维罗纳整合子编码金属β-内酰胺酶（6.4%）和肺炎克雷伯菌碳青霉烯酶（2.1%）。我们的研究发现，大部分CRE分离株中存在碳青霉烯酶。鉴于未来与CRE治疗相关的治疗方法以及通过监测和感染控制干预措施协助控制工作，明确耐药机制很重要。
