30 adult hospitalized patients who have infections due to MDR Acinetobacter baumannii will be enrolled. The eligible patients will receive 100 mg of tigecycline intravenous infusion for 30 minutes followed by 50 mg every 12 hours for 7 to 14 days. Clinical outcomes on effectiveness and safety will be evaluated on daily basis up to 28 days. Follow-up culture of clinical specimen from the site of infection will be obtained on day 3 and at the end of tigecycline therapy. Clinical response is classified as cure, improvement, failure, relapse, death. Microbiological outcome is assessed at the end of treatment and classified as eradication, persistence, colonization, and superinfection. Adverse events, overall 28-day mortality and infection-related mortality will be determined. Length of stay will also be determined.