铜绿假单胞菌耐药性与产β内酰胺酶的关系

Study on the drug resistance and β-lactamases of Pseudomonas aeruginosa

目的分析临床分离的93株铜绿假单胞菌的耐药性与β内酰胺酶类型的关系。方法采用K B法测定亚胺培南等16种抗菌药物对93株铜绿假单胞菌的体外抗菌活性;采用等电聚焦电泳(isoelectricfocusing,IEF)、三维试验、2巯基丙酸抑制试验、聚合酶链反应(PCR)分析β内酰胺酶类型。结果阿米卡星敏感性最高为82.8%,其次依次为头孢吡肟(81.7%)、头孢哌酮/舒巴坦(81.7%)、头孢他啶(80.6%)、美罗培南(77.4%)、亚胺培南(71.0%)。三维试验结果表明,14株(15.1%)产碳青霉烯酶,其中2株产金属酶;15株(16.1%)产AmpC酶,其中2株同时产AmpC酶和超广谱β内酰胺酶(ESBLs)。等电聚焦电泳显示产AmpC的细菌均具有9.0的条带;19号和54号菌株有一个6.3的条带。2巯基丙酸抑制试验筛选金属酶2株阳性,与三维试验结果相符。设计金属酶VIM2特异性引物,PCR反应结果阳性,经克隆测序证实为VIM2型金属酶。结论铜绿假单胞菌感染中产β内酰胺酶较常见,其中产碳青霉烯酶和AmpC酶占一定比率,是造成临床上铜绿假单胞菌对碳青霉烯类和头孢菌素第3、4代耐药的主要原因。

Objective To analyze the resistance and β-lactamases of 93 strains of Pseudomonas aeruginosa. Methods Antimicrobial activity to 93 strains of Pseudomonas aeruginosa were determined by K-B test,and the β-lactamases produced by these strains were characterized by isoelectric focusing,three-dimensional test,2-mercaptopropanoic acid inhibited assays,and polymerase chain reaction (PCR). Results The resistance of amikacin ,cefepime ,cefoperazone/sulbactam,ceftazidime,meropenem were 82.8%,81.7%, 81.7%, 80.6%,77.4%,respectively. The susceptibility of rate imipenem was 71.0%. Three-dimensional test showed that 14 strains produced carbapenemases,only and 2 strain produced metallo-β-lactamase,which was in agreement with the result of 2-mercaptopropanoic acid inhibited assays,13 strains produced AmpC enzymes,and 2 strains produced AmpC enzymes and ESBLs.The 15 strains and other two(Number 19,54) had 1 band on IEF electrophoresis, and the isoelectric points were 9.0 and 6.3 respectively.The 2 metallo-β-lactamases were revealed by amplified PCR products with VIM-2 specific PCR,the production was sequenced and revealed that the found to match with the known sequences of VIM-2. Conclusion The production of carbapenemases and AmpC enzymes was the main cause for multi-drug resistance in Pseudomonas aeruginosa in our hospital.