Successful Use of Colistin Monotherapy as Outpatient Parenteral Antibiotic Therapy for XDR Acinetobacter Hepatic Abscesses

Acinetobacter baumannii is naturally resistant to several classes of antibiotics and readily develops further resistance mechanisms under antibiotic pressure. For patients infected with extremely drug-resistant organisms, effective antibiotic treatments are intravenous and often require inpatient hospitalization for monitoring and dose adjustment. A 31-year-old active duty service member, stationed in Southeast Asia, sustained thermal burns from an electrical arc injury to over 40% of his total body surface area. His hospital course was complicated by multiple extensively drug resistant (XDR) A. baumanii infections including bacteremia and hepatic abscesses. To facilitate discharge to his family, his hepatic abscesses were treated successfully as an outpatient with several weeks of parenteral colistin monotherapy. With regular renal function testing, his dosages were held and/or adjusted to compensate for acute kidney injuries, and he was successfully cleared of his infection. Up to 50% of A. baumannii isolates in American hospitals, including major DOD facilities, are carbapenem resistant. As a result, historically last-line therapies, such as polymyxins, are increasingly used as treatment. New dosing guidance is emphasized to minimize renal toxicities. This case demonstrates the ability to administer parenteral colistin as an outpatient under close supervision.