Acinetobacter baumannii causes severe infections (pneumonia, bacteremia, organ space) with high lethality in hospitalised critically ill patients. It can acquire resistance to all classes of antibiotics (multidrug resistance, MDR) except an 'old' drug, colistin, which may be the only therapeutic option. The addition of minocycline to colistin has been shown to be synergistic in vitro, and may be promising in vivo, but this combination has not been limited to case report or case series in comparison with colistin alone.

The purpose of this double-blind, randomized, parallel, placebo-controlled clinical trial is to assess whether the association of colistin and minocycline reduces significantly the mortality of patients with severe MDR A. baumannii infections compared with colistin alone.

The trial will enroll 94 patients from internal medicine ward and intensive care units (ICU) of an university care hospitals where MDR A. baumannii infection is endemic with epidemic phases. Patients will be randomly allocated to either colistin plus placebo (control arm) or colistin plus minocycline (experimental arm).

Primary end point is overall mortality, defined as death occurring within 28 days from randomisation.

Inclusion Criteria:

• Clinical and microbiological evidence of a severe infection due to multi-drug resistant A. baumannii during hospitalization
• Susceptibility of the A. baumannii isolate to colistin (MIC < or =2 mg/l).

Exclusion Criteria:

• Treatment with one of the study drugs prior to the diagnosis of A. baumannii infection more than 48 hours
• Severe liver dysfunction
• History of prior hypersensitivity to the study drugs
• Pregnancy and lactation

Double blind, Placebo Controlled