鲍曼不动杆菌对氨基糖苷类药物的耐药机制研究

Mechanisms of the aminoglycoside resistance of Acinetobacter baumannii

目的鲍曼不动杆菌(Acinetobacter baumannii,Ab)是引起院内感染的重要病原菌,近年来,对氨基糖苷类药物耐药逐渐升高。文中分析Ab基因同源性及其对氨基糖苷类抗菌药的耐药机制。方法2005年10月至2006年11月,收集临床分离的55株Ab,采用肠杆菌科基因间重复一致序列-聚合酶链式反应(enterobacterial repetitive intergenic consensus se-quence-polymerase chain reaction,ERIC-PCR)方法进行菌株基因组同源性分析。采用PCR方法检测氨基糖苷类修饰酶(Amin-oglycosides modifying enzymes,AME)基因及外排泵基因adeB。结果ERIC-PCR将55株Ab分为2型,其中A型最多为51株,包括2个亚型,A1型39株,A2型12株;B型4株。49株检测出AME基因,aac(3)-Ⅰ、aac(6′)-Ⅰ基因阳性率分别为82%、64%,而aac(3)-Ⅱ、aph(3′)-Ⅵ基因均为阴性。所有菌株均检测出adeB基因。结论55株Ab由2种克隆构成,92.7%为A型。菌株AME基因携带率高,55株均检测出adeB基因,外排泵是否参与耐药有待进一步研究。

Objective Acinetobacter baumannii（Ab） is a major pathogenic bacterium for nosocomial infection,and its resistance to aminoglycosides has been increasing in recent years.Our experiment was to characterize the gene homology of Ab and the mechanisms of its resistance to aminoglycosides.Methods Fifty-five Ab strains were collected in our hospital between October 2005 and November 2006,their genomic homology analyzed by Enterobacterial repetitive intergenic consensus sequence-polymerase chain reaction（ERIC-PCR）.The aminoglycoside modifying enzyme（AME） gene and adeB gene were detected by PCR.ResultsThe analysis of homogenous chromosomal DNA indicated 2 different patterns of the Ab strains,51 of pattern A and 4 of pattern B.The AME gene was detected in 49 of the 55 isolates,of which 82% and 64% harbored aac（3）-Ⅰ and aac（6′）-Ⅰ,respectively,while adeB was found in all the 55 strains.Conclusion The 55 isolates had 2 different patterns,and 92.7% of them were pattern A.In spite of the high percentage of the AME gene,further studies are needed to characterize its contribution to aminoglycoside rsistance.