The invention provides systems and methods for increased clinical efficacy of rifabutin against A. baumannii. The invention takes advantage of the discovery of a ferric-coprogen (FhuE) receptor that is responsible for the uptake of rifabutin into A. baumannii cells. Methods preferably include obtaining a sample from a patient suspected of having an infection; performing a test on the sample to identify an infection of A. baumannii in the patient; and providing a formulation of rifabutin for treating the patient that, when administered to the patient, maximizes a resultant AUC and/or Cmax. The method may include administering the formulation of rifabutin to the patient. Preferably the formulation is delivered to the patient, e.g., by intravenous injection and results in a Cmax is that greater than about 2 mg/L and optionally less than about 50 mg/L.