From March 1995 to March 1997, sulbactam was prospectively evaluated in patients with non-life-threatening multiresistant Acinetobacter baumannii infections. During this period, 47 patients were treated with sulbactam; of them, five were excluded because they had received < or =48 h of sulbactam therapy. A total of 42 patients, 27 males and 15 females with a mean age of 60+/-15 years, were finally evaluated. Infections were as follows: surgical wound, 19; tracheobronchitis, 12; urinary tract, 7; catheter-related bacteraemia, 2; and pneumonia, 2. Eighteen patients received intravenous sulbactam alone (1 g every 8 h) and 24 patients received intravenous sulbactam/ampicillin (1 g:2 g every 8 h) with no major adverse effects. Of the 42 patients, 39 improved or were cured and showed A. baumannii eradication and one patient had persistence of wound infection after 8 days of sulbactam/ampicillin requiring surgical debridement. Two patients died after 3 days of therapy (one of the deaths was attributable to A. baumannii infection). The in-vitro activity of the sulbactam/ampicillin combination was by virtue of the antimicrobial activity exhibited by sulbactam. Killing curves showed that sulbactam was bacteriostatic; no synergy was observed between ampicillin and sulbactam. Our results indicate that sulbactam may prove effective for non-life-threatening A. baumannii infections. Its role in the treatment of severe infections is unknown. However, the current formulation of sulbactam alone may allow its use at higher doses and provide new potential synergic combinations, particularly for those infections by A. baumannii resistant to imipenem.