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.