Al-Obeid Suleiman, Jabri Lina, Al-Agamy Mohammad, Al-Omari Awad, Shibl Atef
J Chemother. 2015 Jun;27(3):156-62. doi: 10.1179/1973947815Y.0000000019. Epub 2015 Apr 13.
Extensively drug-resistant Acinetobacter baumannii (XDRAB) became a worldwide nosocomial threat. The aim of this study was to assess the epidemiology and to evaluate the prevalence of carbapenem-resistant A. baumannii (CRAB). We also discuss therapeutic options for the management of their infections.
Antibiotic susceptibility was determined in 506, 510 and 936 duplicate isolates of A. baumannii isolated in 2006, 2009 and 2012, respectively. In 2012, 12 unique XDRAB strains were isolated from patients with serious ventilator-associated pneumonia (VAP). Susceptibility tests were performed using the microdilution method according to Clinical and Laboratory Standards Institute (CLSI) recommendations. MICs were determined in triplicate by E-test according to the manufacturer's recommendations. Susceptible and multidrug-resistant A. baumannii (MDRAB) strains were detected using CHROMagar Acinetobacter medium. Carbapenem resistant A. baumannii was investigated for carbapenemase production by the modified Hodge test (MHT) and by multiplex PCR. A Synergy test was performed using the E-test method.
Considering years 2006, 2009 and 2012, the susceptibilities to meropenem and imipenem were 64-81.2%, 34.5-45.3%, and 8.3-11%, respectively. Concerning the 12 XDRAB strains, all isolates were susceptible to colistin and resistant to meropenem and imipenem. Culture on CHROMagar Acinetobacter confirmed that all are MDRAB. The gene profiles detected in PCR assays showed that all the strains possess OXA-51.Out of the 12 isolates, 11 possess the oxa-23 gene and one harbours the gene 24/40. A good synergistic effect was detected between colistin and tigecycline.
In this study, A. baumannii susceptibility to carbapenems showed a drastic reduction and represents a major epidemiological concern. The main carbapenem resistance mechanism is mediated by class D-OXA-type enzymes (oxa-23 and oxa-24/40) with Carbapenemase activity. Therapeutic options are exceedingly limited, relying on polymyxin combinations with other antibiotics. We are clearly missing new active agents against XDRAB.
广泛耐药鲍曼不动杆菌（XDRAB）已成为全球医院感染的一大威胁。本研究旨在评估其流行病学情况并评估耐碳青霉烯鲍曼不动杆菌（CRAB）的流行率。我们还将讨论其感染治疗的选择方案。
分别对2006年、2009年和2012年分离出的506株、510株和936株鲍曼不动杆菌重复菌株进行药敏试验。2012年，从患有严重呼吸机相关性肺炎（VAP）的患者中分离出12株独特的XDRAB菌株。根据临床和实验室标准协会（CLSI）的建议，采用微量稀释法进行药敏试验。根据制造商的建议，通过E试验一式三份测定最低抑菌浓度（MIC）。使用CHROMagar不动杆菌培养基检测敏感和多重耐药鲍曼不动杆菌（MDRAB）菌株。通过改良Hodge试验（MHT）和多重聚合酶链反应（PCR）对耐碳青霉烯鲍曼不动杆菌进行碳青霉烯酶产生情况的研究。使用E试验方法进行协同试验。
考虑2006年、2009年和2012年的数据，对美罗培南和亚胺培南的药敏率分别为64 - 81.2%、34.5 - 45.3%和8.3 - 11%。关于这12株XDRAB菌株，所有分离株对黏菌素敏感，对美罗培南和亚胺培南耐药。在CHROMagar不动杆菌培养基上培养证实所有菌株均为MDRAB。PCR检测的基因图谱显示所有菌株均具有OXA - 51。在这12株分离株中，11株具有oxa - 23基因，1株含有24/40基因。检测到黏菌素和替加环素之间有良好的协同作用。
在本研究中，鲍曼不动杆菌对碳青霉烯类药物的敏感性显著降低，这是一个主要的流行病学问题。主要的碳青霉烯耐药机制是由具有碳青霉烯酶活性的D类OXA型酶（oxa - 23和oxa - 24/40）介导的。治疗选择极其有限，依赖于多黏菌素与其他抗生素的联合使用。我们显然缺乏针对XDRAB的新型活性药物。
