【摘要】 目的了解耐亚胺培南铜绿假单胞菌的耐药性与金属β-内酰胺酶(MBLs)的关系。方法2-巯基丙酸协同试验筛选产MBLs菌株;PCR扩增和克隆含有MBLs基因的Ⅰ型整合子,Southern印迹分析MBLs基因的定位;随机引物多态性DNA(RAPD)分析分离株的同源性。结果128株亚胺培南耐药株对阿米卡星、头孢他啶和环丙沙星的耐药率(31.9%、43.6%和61.0%),显著高于亚胺培南敏感株(9.8%、13.9%和24.3%)(P<0.01);分别有6株(4.7%)或9株(7.1%)产VIM-2或IMP-1型MBLs;VIM-2基因位于染色体上的Ⅰ型整合子结构,而IMP-1基因位于23kb的质粒上;RAPD显示8株产IMP-1型MBLs菌株有相同的带谱。结论产VIM-2和IMP-1型MBLs铜绿假单胞菌可导致医院感染。更多还原

【Abstract】 OBJECTIVE To investigate the possible contribution of metallo-β-lactamases(MBLs) and characterization of their containing integron in Pseudomonas aeruginosa clinical strains resistant to carbapenems.METHODS Clinical strains resistant to carbapenems were screened for MBLs production by a disk diffusion synergy test and subjected to PCR assays with primers specific for MBLs and class Ⅰ integrons conserved sequence.Sequence analysis was conducted to identify the prevalence of MBLs gene and characterization of its containing integron.Southern blot analysis was done for the location of IMP-1 gene cassettes.Molecular typing was carried out by random amplified polymorphic DNA(RAPD) and conjugation experiment was used to study the transfer of resistance.RESULTS The rates of imipenem-resistant strains to amikacin,ceftazidine and ciprofloxacin were obviously high(31.9%,43.6% and 61.0%) than that of nonresistant ones(9.8%,13.9% and 24.3%).Among 128 imipenem-resistant strains,6 or 9 isolates were positive for VIM-2 or IMP-1 gene,respectively.Sequence analysis of these VIM-2 containing integrons revealed 2269 bp class Ⅰ integrons structure that contained two gene cassettes,ICA PCR and Southern blot indicated these IMP-1 containing class Ⅰ integron which carried were located in plasmid about 23kb.Crude extraction of β-lactamases showed imipenem-hydrolyzing activity and could be inhibited by treatment with EDTA.RAPD typing suggested these 9 strains exhibit similar pattern. CONCLUSIONS BlaVIM-2 and blaIMP-1 are prevalent in P.aeruginosa clinical strains resistant to carbapenems and may lead to nosocomial infection.更多还原