医院感染铜绿假单胞菌多重耐药机制的研究

目的了解近3年医院感染铜绿假单胞菌的耐药表型、产酶情况及Ⅰ类整合子在耐药基因播散中所起的作用。方法采用平皿二倍稀释法检测MIC；改良三维法对β内酰胺酶进行分析；应用PCR技术检测Ⅰ类整合子，并通过测序分析其所携带耐药基因。结果铜绿假单胞菌对多种抗菌药物耐药率不断上升，细菌可产生多种β内酰胺酶，Ⅰ类整合子阳性率为42．4％，所携带耐药基因包括aadB，aadA2，aac6-Ⅱ和PSE-1。结论多重耐药铜绿假单胞菌比例不断上升．这与细菌可产生多种β内酰胺酶及整合子可介导耐药基因横向播散相关，临床医师务必根据药物敏感试验和本单位耐药监测情况合理选择抗菌药物，以减少多重耐药菌的发生和发展。

Study on the resistance mechanism of nosocomial isolates of multi-resistant Pseudomonas aeruginosa

Objective To study the antimicrobial susceptibility of Pseudomonas aeruginosa, the beta-lactamases and the role of class 1 integron-mediated multidrug resistance in multi-resistant strains isolated in the last 3 years. Methods The dilution method was conducted to determine minimum inhibitory concentration (MIC). Modified three-dimensional method was used to differentiate various beta-lactamases. PCR was used to detect class 1 integron. DNA sequencing was adopted to analyze the resistance-related genes. Results The resistance rate of P. aeruginosa to many antibiotics increased gradually. The beta-lactamases produced by these multi-resistant P. aeruginosa include ESBLs, AmpC beta-lactamases and some carbapenemases. The prevalence of class 1 integron was 42.4%. Resistance-related gene cassette in the integron included aadB, aadA2, aac6-II, and PSE-1. Conclusions The prevalence of multi-resistant P. aeruginosa increases gradually. This is associated with the production of multiple beta-lactamases by P. aeruginosa and transverse spread of resistant genes mediated by class 1 integron. Clinicians should choose appropriate antibiotic therapy based on bacterial susceptibility to reduce or prevent the emergence and development of multi-resistant strains.