Department of Laboratory Medicine, College of Medicine, Kyung Hee University, Seoul, Korea.
Yonsei Med J. 2009 Dec 31;50(6):764-70. doi: 10.3349/ymj.2009.50.6.764. Epub 2009 Dec 18.
Since November 2006, imipenem-resistant Acinetobacter baumannii isolates have increased in Kyung Hee University Hospital in Seoul, Korea. The purpose of this study was to determine the genetic basis and molecular epidemiology of outbreak isolates.
Forty-nine non-repetitive isolates of the 734 IRAB strains were investigated in order to determine their characteristics. The modified Hodge and the ethylenediaminetetraacetic acid (EDTA)-disk synergy test were performed for the screening of carbapenemase and metallo-beta-lactamase production. Multiplex polymerase chain reaction (PCR) assays were performed for the detection of genes encoding for OXA-23-like, OXA-24-like, OXA-58-like and OXA-51-like carbapenemase. Pulsed-field gel electrophoresis (PFGE) was performed for strain identification.
All isolates showed 100% resistance to ciprofloxacin and gentamicin, 97.9% resistance to cefepime, piperacillin/tazobactam, aztreonam, ceftazidime and piperacillin, 93.9% resistance to tobramycin and 57.1% resistance to amikacin. All of the 49 isolates (100%) showed positive results in the modified Hodge test and negative results in the EDTA-disk synergy test. They all (100%) possessed the encoding gene for an intrinsic OXA-51-like carbapenemase and an acquired OXA-23-like carbapenemase in the multiplex PCR assay. PFGE patterns revealed that all isolates were clonally related from A1 to A14.
It is concluded that all of the 49 IRAB isolates acquired resistance to imipenem by producing OXA-23 carbapenemase and they might have originated from a common source.
自 2006 年 11 月以来，韩国首尔庆熙大学医院的耐碳青霉烯鲍曼不动杆菌分离株不断增加。本研究旨在确定暴发分离株的遗传基础和分子流行病学。
为了确定其特征，对 734 株 IRAB 株中的 49 个非重复分离株进行了调查。进行改良霍氏试验和乙二胺四乙酸（EDTA）-圆盘协同试验以筛选碳青霉烯酶和金属β-内酰胺酶的产生。进行多重聚合酶链反应（PCR）检测以检测编码 OXA-23 样、OXA-24 样、OXA-58 样和 OXA-51 样碳青霉烯酶的基因。进行脉冲场凝胶电泳（PFGE）以鉴定菌株。
所有分离株对环丙沙星和庆大霉素的耐药率均为 100%，对头孢吡肟、哌拉西林/他唑巴坦、氨曲南、头孢他啶和哌拉西林的耐药率为 97.9%，对妥布霉素的耐药率为 93.9%，对阿米卡星的耐药率为 57.1%。49 株分离株（100%）改良霍氏试验阳性，EDTA 圆盘协同试验阴性。所有分离株（100%）在多重 PCR 检测中均携带固有 OXA-51 样碳青霉烯酶和获得性 OXA-23 样碳青霉烯酶编码基因。PFGE 模式显示，所有分离株均从 A1 到 A14 呈克隆相关。
所有 49 株耐碳青霉烯鲍曼不动杆菌分离株均通过产生 OXA-23 碳青霉烯酶获得对亚胺培南的耐药性，它们可能来自共同的来源。
