耐亚胺培南鲍曼不动杆菌碳青霉烯酶及整合子分布

目的 了解耐亚胺培南鲍曼不动杆菌碳青霉烯酶及整合子分布情况.方法 收集天津医科大学总医院2008年1月至2010年3月期间,103株亚胺培南耐药鲍曼不动杆菌临床标本.用Vitek-2系统鉴定细菌,并进行药敏试验,通过改良Hodge试验、改良三维试验和2-巯基丙酸协同试验初筛碳青霉烯酶,多重PCR同时检测4种OXA型碳青霉烯酶基因、2种金属酶基因及整合酶基因,对整合子可变区进行PCR检测及序列分析.结果 103株鲍曼不动杆菌中,改良Hodge试验检出碳青霉烯酶阳性75株(72.8%),改良三维试验检出产碳青霉烯酶菌株80株(77.7%),未检出产金属酶菌株.PCR检出blaOXA-51-like+bsaOXA-23-like+int11基因84株,blaOxA-51-like+blaOXA-23-like阳性5株,blaOXA-51-like+intll阳性8株,blaOXA-51-like+blaOXA-24-like阳性2株,仅blaOXA-51-like阳性4株,blaOXA-58-like、金属酶基因(IMP-1、VIM-2)及Ⅱ类整合酶基因(intI2)均阴性.89株(96.7%)Ⅰ类整合酶阳性株均扩增出可变区,检出2种耐药基因盒组合形式:aacA4-catB8-aadAl(2 300 bp)81株,aacCl-orfX-orfX-orfX'-aadAla(3 000 bp)8株.结论 鲍曼不动杆菌对碳青霉烯类耐药及多重耐药主要与其携带的OXA-23型碳青霉烯酶和Ⅰ类整合子有关.

Abstract：

Objective To investigate the carbapenemases and integrons in imipenem-resistant Acinetobacter baumannii. Methods One hundred and three Acinetobacter baumannii were collected from Janurary 2008 to March 2010 in Tianjin Medical University General Hospital. The identification of strains and antimicrobial susceptibility test were performed by using Vitek-2 compact automatic system. Isolates of imipenem-resistant A. baumannii were screened for carbapenemases by modified Hodge test, improved threedimensional test and 2-mercaptopropionic acid synergy test. Isolates were then subjected to the multiplex PCR targeting genes encoding for OXA type carbapenemases, metallo-β-lactamases (MBLs) and integrases. The variable regions of integrons were amplificated and sequenced. Results Among the 103 isolates, 75 (72. 8% ) demonstrated positive in the modified Hodge test, 80 (77.7%)were positive in the improved three-dimensional test. No MBLs was found in the 2-mercaptopropionic acid synergy test. Eightyfour isolates were positive for blaOXA-51-like, blaOXA-23-like, and intI1; five were positive for blaOXA-51-like and blaOXA-23-like ;eight were positive for blaOXA-51-like and int11 ;two were positive for blaOXA-51-like and blaOXA-24-like ;four were only found positive for blaOXA-51-like. The blaOXA-58-like, IMP-1, VIM-2 and intI2 genes were all negative. Eighty-nine(96. 7% )of the intI1 positive strains owned the variable region. Two different cassettes arrangements were identified within class 1 integrons:81 isolates harbored aacA4-catB8-aadAI (2 300 bp) and 8 harbored aacCl-orX-orfX-orX'-aadAla (3 000 bp ) . Conclusion The presence of OXA-23 carbapenermase and class Ⅰ integrons are correlated with Acinetobacter baumannii resistant to carbapenems and multi-drug resistance.

Detection of carbapenemases and integrons distribution among imipenem-resistant Acinetobacter baumannii isolates

Objective To investigate the carbapenemases and integrons in imipenem-resistant Acinetobacter baumannii. Methods One hundred and three Acinetobacter baumannii were collected from Janurary 2008 to March 2010 in Tianjin Medical University General Hospital. The identification of strains and antimicrobial susceptibility test were performed by using Vitek-2 compact automatic system. Isolates of imipenem-resistant A. baumannii were screened for carbapenemases by modified Hodge test, improved threedimensional test and 2-mercaptopropionic acid synergy test. Isolates were then subjected to the multiplex PCR targeting genes encoding for OXA type carbapenemases, metallo-β-lactamases (MBLs) and integrases. The variable regions of integrons were amplificated and sequenced. Results Among the 103 isolates, 75 (72. 8% ) demonstrated positive in the modified Hodge test, 80 (77.7%)were positive in the improved three-dimensional test. No MBLs was found in the 2-mercaptopropionic acid synergy test. Eightyfour isolates were positive for blaOXA-51-like, blaOXA-23-like, and intI1; five were positive for blaOXA-51-like and blaOXA-23-like ;eight were positive for blaOXA-51-like and int11 ;two were positive for blaOXA-51-like and blaOXA-24-like ;four were only found positive for blaOXA-51-like. The blaOXA-58-like, IMP-1, VIM-2 and intI2 genes were all negative. Eighty-nine(96. 7% )of the intI1 positive strains owned the variable region. Two different cassettes arrangements were identified within class 1 integrons:81 isolates harbored aacA4-catB8-aadAI (2 300 bp) and 8 harbored aacCl-orX-orfX-orX'-aadAla (3 000 bp ) . Conclusion The presence of OXA-23 carbapenermase and class Ⅰ integrons are correlated with Acinetobacter baumannii resistant to carbapenems and multi-drug resistance.