Combination carbapenem-sulbactam therapy for critically ill patients with multidrug-resistant Acinetobacter baumannii bacteremia: four case reports and an in vitro combination synergy study.

Infections caused by multidrug-resistant Acinetobacter baumannii have become a therapeutic challenge for clinicians worldwide. Although colistin and tigecycline have been successful in treating patients with these infections, these agents are not available on a worldwide basis. We describe four critically ill patients in Taiwan who were diagnosed with multidrug-resistant Acinetobacter baumannii bacteremia. All bacterial isolates from these patients were resistant to commonly available antibiotics, including carbapenems and sulbactam; however, combination therapy with a carbapenem and sulbactam led to favorable clinical outcomes in all four patients. We also conducted an in vitro study using isolates from these patients that showed that this drug combination had a synergistic effect with enhanced antibacterial activity against the isolates. Thus, a carbapenem-sulbactam combination may be a therapeutic alternative for multidrug-resistant Acinetobacter baumannii bacteremia in countries where colistin and tigecycline are not available for clinical use.