耐碳青霉烯铜绿假单胞菌的耐药基因检测及分析

Detection and analysis of carbapenem resistant determinants in Pseudomonas aeruginosa

目的探讨我院临床分离耐碳青霉烯铜绿假单胞菌的耐药特征及β-内酰胺酶基因的携带情况和基因型分布。方法收集经VITEK-2全自动细菌鉴定及药敏分析系统鉴定的铜绿假单胞菌,筛选耐碳青霉烯菌99株,碳青霉烯敏感菌54株,分析其耐药特征;采用PCR法检测7种主要β-内酰胺酶基因(blaTEM、blaPER、blaVEB、blaSHV、blaOXA、blaVIM及blaIMP)携带情况,并分析其与耐药相关性。结果碳青霉烯耐药菌中β-内酰胺酶基因阳性检出率为24.2%(24/99),单个基因携带率由高到低分别为IMP型13.1%(13/99),OXA-10型9.1%(9/99),TEM型8.1%(8/99),PER型6.1%(6/99),SHV型1.0%(1/99),VIM型1.0%(1/99);同时携带2种基因的菌株为4.0%(4/99),同时携带3种基因的菌株为3.0%(3/99),其中2株同时携带TEM、PER和OXA-10酶基因,另1株同时携带TEM、PER和VIM基因,这些菌中PER基因携带率最高为85.6%(6/7);而碳青霉烯敏感菌均未检出耐药基因;碳青霉烯耐药菌对11种常用抗菌药物的耐药率较高,除庆大霉素45.5%(45/99)和妥布霉素38.4%(38/99)外均大于66%,与碳青酶烯敏感菌的耐药率有显著性差异(P<0.01)。结论我院耐碳青霉烯铜绿假单胞菌主要产IMP型金属酶,产酶株耐药性明显高于非产酶株。

Objectives To investigate the resistance features, β-lactamase carriage and genotype distribution in clinical isolates of carbapenem-resistant Pseudomonas aeruginosa. Methods After automatic identification and susceptibility testing, 99 carbapenem-resistant isolates and 54 carbapenem-sensitive isolates were collected and resistance features were analyzed. Seven β-lactamase genes （（blaTEM, blaPER, blaVEB, blaSHV, blaOXA, blaVIM and blaIMP） were detected by PCR and the their correlation with resistance was analyzed. Results The positive rate of β-lactamase genes in carbapenem-resistant isolates was 24.2% （24/99）, with 13.1% （13/99） of blaIMP 9.1% （9/99） of blaoxA-10, 8.1% （8/99） of blaxEM, 6.1% （6/99） of blapER, 1.0% （1/99） of bla shv 1.0% （1/99） of bla VIM, respectively. The co-production rate of two resistance genes was 4.0% （4/99）, and that of three resistance genes was 3.0% （3/99）. Two strains co- produced TEM, PER and OXA-10 enzyme-encoding genes, and one co-produced TEM, PER and VIM enzyme- encoding genes. The carriage rate of PER was highest （85.6%, 6/7） among these strains with more than one resistance genes. No β-lactamase genes were detected in carbapenem-sensitive isolates. High resistance to 11 commonly-used antibiotics was detected in carbapenem-resistant isolates, with resistance rates more that 66% except gentamycin （45.5%, 45/99） and tobramycin （38.4%, 38/99）. The resistance rate of carbapenem-resistant isolates was significantly higher than that of the carbapenem-sensitive isolates （P〈0.01）. Conclusion The main β-lactamase gene produced by carbapenem-resistant P. aeruginosa was IMP in our hospital, and drug resistance was more commonly detected in strains producing β-lactamase genes.