Objective To understand antimicrobial resistance and therapeutic efficacy of imipenem/cilastatin and meropenem for treatment of multidrug-resistant Pseudomonas aeruginosa (MDRPA)from patients with mechanical ventilation.Methods From January 2010 to December 2015,78 patients with mechanical ventilation and isolated MDRPA from sputum cultures were selected and divided into imipenem/cilastatin (n=44)and meropenem(n=34) treatment groups,basic condition,time of emergence of drug resistance,and therapeutic efficacy of antimicrobial agents between two groups were compared.Results The basic data of two groups were comparable,before treat-ment by imipenem/cilastatin and meropenem,resistance rates of Pseudomonas aeruginosa (P .aeruginosa )to quinolones,ceftazidime,piperacillin,and amikacin were not significantly different (all P >0.05).After patients received antimicrobial agents for 6 days,difference in antimicrobial resistance between imipenem /cilastatin and meropenem treatment groups were not significantly different (22.73% vs 8.82%,P >0.05).On the 8th,10th,and 12th day of treatment,resistance rates of imipenem treatment group were 40.91%,77.27%,and 97.73%, respectively,which were all higher than meropenem treatment group (17.65%,32.35%,44.12%,respectively,all P <0.05).After the treatment with different antimicrobial agents,the average time for the emergence of resistance in imipenem/cilastatin and meropenem treatment group were 9.0 days and 13.5 days respectively.Therapeutic efficacy between two groups was not significantly different (64.71% vs 74.19%,P =0.41).Conclusion Compared with meropenem,imipenem/cilastatin shows higher risk for the emergence of drug resistance during therapy of P . aeruginosa infection in patients with mechanical ventilation,there is no significant difference in therapeutic efficacy between two groups of patients after 7 days of treatment.