耐碳青霉烯类抗生素鲍曼不动杆菌的药物敏感性及其分子特征

Susceptibility and molecular mechanism of carbapenem- resistant Acinetobacter baumannii

目的：调查重症监护病房（ICU）耐碳青霉烯鲍曼不动杆菌（CRAB）的药物敏感性及其分子特征。方法收集2010年深圳市人民医院ICU患者分离CRAB 48株，琼脂稀释法测定亚胺培南等15种抗菌药对CRAB的最低抑菌浓度（MIC），聚合酶链式反应（PCR）和DNA测序分析CRAB碳青霉烯酶基因型，脉冲场凝胶电泳（ PFGE）分析菌株同源性。结果多黏菌素B对48株CRAB抗菌活性最高（敏感性为100％）， MIC50/MIC90均为1μg ＆#183; mL-1，其次为米诺环素，敏感性为95.8％，MIC50/MIC90均为4μg＆#183; mL-1，43株CRAB对替加环素中介，MIC50/MIC90均为4μg＆#183; mL-1。43株CRAB携带blaOXA-23-like ，对亚胺培南和美罗培南高度耐药，其MIC在16～64μg＆#183; mL-1；3株CRAB携带blaOXA-58-like，2株CRAB携带ISAba1-blaOXA-51-like ，亚胺培南和美罗培南的MIC在8～16μg＆#183; mL-1。48株CRAB扩增blaOXA-24-like、blaOXA-143-like、金属酶基因及KPC酶基因均阴性。48株CRAB经PFGE分型共分4型，以A型42株（87.5％）为主要流行克隆，均携带blaOXA-23-like。结论2010年携带blaOXA-23-like的CRAB高耐药克隆在我院ICU流行。

Objective To investigate the susceptibility of antimicrobial agents, carbapenemase genotypes and clonal relatedness among carbap-enem-resistant Acinetobacter baumannii （ CRAB） isolated from intensive care unit （ ICU） in Shenzhen People′s Hospital.Methods Forty-eight non-duplicated CRAB isolates were collected from ICU in this hospital in 2010.The minimum inhibitory concentrations （ MICs） of fifteen anti-microbial agents against CRAB were detected by agar dilution method.Polymerase chain reaction （ PCR） and DNA sequencing were used to in-vestigate the carbapenemase genotype among CRAB.All isolates were typed by pulse field gel electrophoresis （ PFGE ）.Results Polymixin B showed the highest activity against forty-eight CRAB isolates （ suscepti-bility of 100%） , with the MIC50/MIC90 of 1 μg＆#183; mL -1 , followed by mi-nocycline （susceptibility of 95.8%）, with the MIC50/MIC90 of 4 μg＆#183; mL -1, and tigecycline （intermediate of 89.6%）, with the MIC50/MIC90 of 4 μg＆#183; mL-1 , respectively.Approximately ninety percent （43/48 ） of CRAB isolates harbored blaOXA-23-like , which showed high resistance to imipenem and meropenem , with the main distribution of MICs ranging from 16 to 64 μg ＆#183; mL-1.Three and two CRAB isolates harbored＆amp;nbsp;blaOXA-58-like and ISAba1-blaOXA-51-like, respectively.Both of them exhibited intermediate resistance against imipenem and meropenem, with the main distribution of MICs ranging from 8 to 16 μg＆#183; mL-1.blaOXA-24-like, blaOXA-143-like, metallo-β-lactamase and KPC genes were not detected in any of isolates.Four distinct PFGE patterns were observed among forty-eight isolates of CRAB.All of type A isolates harbored blaOXA-23-like , accounting for 87.5%（42/48） of CRAB.Conclusion The spread of CRAB clone harboring blaOXA-23-like occurred in ICU of our hospital during 2010.