Colistin, meropenem and rifampin in a combination therapy for multi-drug-resistant Acinetobacter baumannii multifocal infection. A case report.

A 16 year-old girl underwent a multifocal (lungs, skin, soft tissues) infection due to multiresistant Acinetobacter baumannii after a car crash. To treat such a severe disease we used a combination therapy of colistin (2 millions Units twice/day), rifampicin (600 mg/day), meropenem (1 g 3 times a day) after a synergistic activity test was performed (checkerboard method on Mueller-Hinton broth and 5x10(5) cfu/mL inoculum). After 24 days, when a significant clinical improvement was gained, the 3-drugs combination therapy was replaced with i.v. levofloxacin 500 mg twice/day but, after 10 days of quinolones therapy, fever started again and the same multidrug resistant (MDR) A. baumannii was isolated from the skin grafts, central venous catheter tip and bronchial alveolar lavage. A combination therapy with colistin and meropenem was therefore started and definitive defervescence was obtained after 10 days. This therapy was continued for 70 days even if the patient was apyretic because A. baumannii was still present in the skin secretions. After 109 days of hospitalization in our intensive care unit, the patient was transferred to a rehabilitative unit. This case shows how useful is, in selected cases, rediscovering old antibiotic drugs, specially when they are adopted as a combination therapy, and highlights the importance of the clinical microbiological laboratory as it may help clinicians in choosing the best drugs combination.