IN-VITRO ACTIVITY OF AMPICILLIN-SULBACTAM AGAINST CLINICAL MULTIRESISTANT ACINETOBACTER-BAUMANNII ISOLATES

We evaluated the in vitro activity of ampicillin-sulbactam in comparis on with that of broad-spectrum antimicrobial agents against Acinetobac ter baumannii isolates. Two hundred and twelve clinical isolates colle cted between January 1993 and March 1995 from two tertiary hospitals l ocated in Sao Paulo, Brazil were tested for susceptibility by the disk diffusion method against several broad-spectrum antimicrobial agents, including imipenem, ciprofloxacin, ceftazidime, aztreonam, amikacin, and polymyxin B. All strains were susceptible to polymyxin B. The seco nd most active compound was the combination ampicillin-sulbactam (88% susceptibility). Only 79% of the isolates were susceptible to imipenem . Ciprofloxacin was active against GO (28%) and amikacin against 34 (1 6%) isolates. Ceftazidime was the most active cephalosporin; however, only 9% of the isolates were susceptible to this compound. Both aztreo nam and ampicillin alone showed very poor activity against this specie s (1% susceptibility). The prevalence of severe infections due to A. b aumannii is increasing very rapidly in the tertiary hospitals of Sao P aulo and there are very few options for the treatment of these infecti ons. Polymyxin B is invariably in vitro active against this species; h owever, this compound can cause severe side effects and is not commerc ially available for intravenous use in Brazil and in several other cou ntries. Our results indicated that the combination ampicillin-sulbacta m may be an alternative drug for the treatment of infections due to mu ltiresistant A. baumannii; however, further studies are necessary to e valuate the clinical role of this compound for the treatment of severe infections.