PER-1型超广谱β-内酰胺酶在铜绿假单胞菌中的流行分析

The analysis of high prevalence of PER-1 type ESBLs harbored in Pseudomonas aeruginosa

目的调查超广谱β-内酰胺酶(ESBLs)以及具碳青霉烯酶活性的OXA酶在铜绿假单胞菌中的流行状况。方法针对1997～2003年间本院收集的具临床意义的铜绿假单胞菌,采用8对通用Class A和Class D类超广谱β-内酰胺酶基因引物对其进行聚合酶链反应(PCR),根据结果再进行长片段引物扩增和序列测定;对PCR扩增阳性株与受体菌利福平耐药铜绿假单胞菌PU21行转移接合试验;采用琼脂平皿稀释法测定所有受试菌的MIC;运用脉冲场凝胶电泳(PF-GE)方法确定菌株间的遗传相关性。结果47株临床分离铜绿假单胞菌中共检出28株PER阳性菌株,经部分长片段产物序列测定证实为PER-1型超广谱β-内酰胺酶;该产酶菌株经转移接合试验无法将耐药性传递给受体菌;药敏结果显示耐药表型与基因型间有很好相关性,对哌拉西林和头孢他啶高度耐药,同时产酶株对亚胺培南呈现100%的耐药性,对哌拉西林-三唑巴坦亦有一定程度的耐药;PFGE结果显示各菌株间存在垂直传播或有较近遗传相关性。结论本院存在产PER-1型ESBLs铜绿假单胞菌的流行。

Objective To investigate the distribution of ESBLs and OXA-type of cabarpenemase harbored in Pseudomonas aeruginosa. Methods Non-repeated and clinical important Pseudornonas aeruginosa were isolated from the People＇ s Hospital of Jiangsu Province from 1997 to 2003. Eight pairs of versatile primers were used to detect the appearance of ESBLs, according to PCR results, a pair of PER-1 gene primers were adopted to amplify and partial of the products were determined by DNA sequencing. Conjugation testing were used to transfer the resistance from wild-type Pseudornonas aeruginosa to recipient cell rifampin resistant Pseudomonas aeruginosa reference strain PU21 ; Agar dilution methods were exerted to determine the MIC value of four antipseudomonal antibiotics against Pseudomonas aeruginosa, according to CLSI standards ; Finally, the homology of PER-1 producing isolates was determined by PFGE. Results Of 47 isolates, 28 harbored bla PER-1. None of other ESBLs was detected. The PER-1 harbored Pseudomonas aeruginosa couldn＇ t confer the resistance to the recipient cell Pseudomonas aeruginosa PU21. Results of antimicrobial agent susceptibility demonstrated that there were high co-relationship between genotype and resistance, exhibiting high resistance to piperacillin and ceftazadime. PER-1 producer also displayed an overall resistance to imipenem and a relevant resistant rate to piperacillin-tazobactam. PFGE typing revealed that vertical transmission occurred among those isolates. Conclusions PER-1 type of ESBL harbored Pseudomonas aeruginosa disseminated in our hospital.