Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, South Korea.
Int J Antimicrob Agents. 2012 Jan;39(1):81-5. doi: 10.1016/j.ijantimicag.2011.08.006. Epub 2011 Oct 12.
Although many studies have been performed on carbapenem-resistant Acinetobacter baumannii, only a few studies have addressed carbapenem resistance in Acinetobacter spp. other than A. baumannii (non-baumannii Acinetobacter). Amongst 287 Acinetobacter spp. isolates from patients with bacteraemia in a South Korean hospital collected between 2003 and 2010, 160 (55.7%) were non-baumannii Acinetobacter spp. Antimicrobial susceptibility testing was performed and the effect of efflux pump inhibitors was examined. Antimicrobial resistance genes were identified and pulsed-field gel electrophoresis (PFGE) analysis was performed. OprD expression was also evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), and CarO disruption was investigated by PCR. Seventeen non-baumannii Acinetobacter isolates (10.6%) were resistant to imipenem or meropenem, comprising eight Acinetobacter pittii (or Acinetobacter genomospecies 3), four Acinetobacter nosocomialis (or Acinetobacter genomospecies 13TU), two Acinetobacter genomospecies 'close to 13TU', two Acinetobacter bereziniae (or Acinetobacter genomospecies 10) and one Acinetobacter genomospecies 16. bla(IMP-1) genes were detected in seven and two carbapenem-resistant A. pittii and A. bereziniae isolates, respectively. PFGE showed that A. pittii isolates carrying bla(IMP-1) belonged to the same clone. In addition, bla(SIM-1) and bla(PER-1) genes were simultaneously identified in two A. nosocomialis isolates. In four isolates (one each of A. pittii, A. nosocomialis, Acinetobacter genomospecies 'close to 13TU' and Acinetobacter genomospecies 16), efflux pumps were implicated in the increase in carbapenem minimum inhibitory concentrations. No decreased expression of OprD was identified in any carbapenem-resistant non-baumannii Acinetobacter isolates, and disruption of carO was also not detected. Clonal spread of carbapenem-resistant A. pittii carrying bla(IMP-1), which contributes to a high resistance rate in this species, was identified. The bla(IMP-1) and bla(SIM-1) genes were first identified in A. bereziniae and A. nosocomialis, respectively. Since no carbapenem resistance mechanisms could be identified, further efforts to find the resistance mechanism should be made.
虽然已经有许多关于耐碳青霉烯鲍曼不动杆菌的研究，但只有少数研究涉及除鲍曼不动杆菌（非鲍曼不动杆菌）以外的其他不动杆菌属的碳青霉烯耐药性。在 2003 年至 2010 年间，从韩国一家医院血培养的 287 株不动杆菌属分离株中，有 160 株（55.7%）为非鲍曼不动杆菌属。进行了药敏试验，并检测了外排泵抑制剂的作用。鉴定了抗菌药物耐药基因，并进行了脉冲场凝胶电泳（PFGE）分析。还通过实时定量聚合酶链反应（qRT-PCR）评估了 OprD 的表达，并通过 PCR 研究了 CarO 的缺失情况。17 株非鲍曼不动杆菌属分离株（10.6%）对亚胺培南或美罗培南耐药，包括 8 株醋酸钙不动杆菌（或不动杆菌基因组种 3）、4 株鲍氏不动杆菌（或不动杆菌基因组种 13TU）、2 株不动杆菌基因组种“接近 13TU”、2 株醋酸钙不动杆菌（或不动杆菌基因组种 10）和 1 株不动杆菌基因组种 16。在 7 株耐碳青霉烯的醋酸钙不动杆菌属和 2 株醋酸钙不动杆菌属分离株中检测到 bla(IMP-1)基因。PFGE 显示携带 bla(IMP-1)的醋酸钙不动杆菌属分离株属于同一克隆。此外，在 2 株鲍氏不动杆菌属分离株中同时鉴定出 bla(SIM-1)和 bla(PER-1)基因。在 4 株分离株（醋酸钙不动杆菌属、鲍氏不动杆菌属、不动杆菌基因组种“接近 13TU”和不动杆菌基因组种 16）中，外排泵参与了碳青霉烯类最低抑菌浓度的增加。在任何耐碳青霉烯的非鲍曼不动杆菌属分离株中均未发现 OprD 表达降低，也未检测到 carO 的缺失。携带 bla(IMP-1)的耐碳青霉烯鲍曼不动杆菌属克隆传播被确定为该种高耐药率的原因。bla(IMP-1)和 bla(SIM-1)基因分别首次在醋酸钙不动杆菌属和鲍氏不动杆菌属中被鉴定。由于无法确定碳青霉烯类耐药机制，应进一步努力寻找耐药机制。
