Relationship between antimicrobial susceptibility and highly active β-lactamases in Pseudomonas aeruginosa

Objective To investigate the antimicrobial resistance and the prevanlence of production of AmpC β-lactamases,extended-spectrum β-lactamases(ESBLs)and metallo β-lactamases(MBLs)in Pseudomonas aeruginosa(P.aeruginosa)clinical isolates,for guiding the rational use of antibiotics. Methods Antimicrobial susceptibility tests were done by Kirby-Bauer disk diffusions method,the phenotypes of P.aeruginosa strains harboring AmpC β-lactamases and /or ESBLs were detected by modified three-dimensional extract test,while MBLs were identified using MBL E-test strips. Results The susceptibility rate of 186 P.aeruginosa clinical isolates to imipenem was the highest about 82.3%,as to ciprofloxacin,piperacillin/tazobactam,ceftazidime,amikacin,cefoperazone/sulbactam were 75.3%,74.2%,72.6%,71.0%,70.4% respectively,but to ticarcillin,cefoperazone,aztreonam were no more than 60%.The resistant rates to cefotaxime and ceftriaxone were 61.8% and 55.9% respectively.AmpC β-lactamases,Amcp β-lactamases combined with ESBLs,ESBLs and MBLs producing strains were detected in 8.6%,2.7%,14.5% and 4.8% of P.aeruginosa respectively. Conclusion The resistant phenomenon of P.aeruginosa clinical isolates should not be ignored,production of highly active β-lactamases is one of resistant mechanisms in P.aeruginosa,imipenem is still the best choice for treating infection caused by P.aeruginosa.