Antimicrobial Agents Combination Against Metallo-β-lactamases Producing Acinetobacter baumannii:An Applied Research

OBJECTIVE To understand in vitro the antibacterial combination activity on the metallo-β-lactamases producing Acinetobacter baumannii(MABA) in order to provide laboratory data for clinical treatment with domestic drug.METHODS All strains were isolated and identified by routine procedure and VITEK-2 automatic bacterial identification instrument.Routine drug susceptibility was tested by K-B paper diffusion method and MIC detection by agar plate dilution method following the instruction of CLSI.RESULTS The positive rate of produced metallo-β-lactamases in 75 A.baumannii(ABA) strains was 96.00%.The inhibitory rate of polymyxin B,imipenem,meropenem,and piperacillin/tazobactam to metallo-β-lactamases-producing ABA were 98.61%,79.17%,73.61% and 30.56%,respectively.Other drugs inhibitory rate(cefpirome,levofloxacin,ceftazidime,minocycline,cefoperazone/sulbactam,and amikacin) was less than 30.00%.The synergy of cefoperazone/sulbactam combined with polymyxin B,minocycline,and amikacin to metallo-β-lactamases-producing ABA were 25.00%,30.56%,and 43.06%.The synergy of piperacillin/tazobactam combined with polymyxin B,minocycline,and amikacin to metallo-β-lactamases-producing ABA were 22.22%,30.56%,and 38.89%.CONCLUSIONS Clinic should be according to the results of drug susceptibility test to select the effective antimicrobial agent to treat the common infection caused by MABA which prudently using carbapenems drug.But of drug combination(cefoperazone/sulbactam or piperacillin/tazobactam combines with amikacin or minocycline) or polymyxin B is suggested for treating severe infection or multi-drug resistant ABA infection in order to control them effectively and to prevent diffusion of drug resistant strains in nosocomial infection.