Managing Acinetobacter baumannii infections

Abstract

We reviewed recent data about epidemiology of Acinetobacter baumannii, resistance mechanisms, and therapeutic options for severe infections caused by multidrug-resistant strains. A. baumannii is a major cause of nosocomial infections affecting mainly to debilitating patients in the ICU, although the spread to regular wards and to long-term care facilities is increasing. It is characterized by its great persistence in the environment and to have an extraordinary capability to develop resistance to all antimicrobials. Carbapenems may not be considered the treatment of choice in areas with high rates of carbapenem-resistant A. baumannii. Nowadays, polymyxins are the antimicrobials with the greatest level of in-vitro activity against A. baumannii. Colistin is the most widely used in clinical practice although polymyxin B seems to be associated with less renal toxicity. Colistin is administered intravenously as its inactive prodrug colistimethate. A loading dose of 9 million IU and subsequently high, extended-interval maintenance doses (4.5 million IU/12 h) are recommended. Combination therapy instead of monotherapy increases the rates of microbiological eradication although no clinical study has demonstrated a reduction in clinical outcomes (mortality or length of stay). The optimal treatment for multidrug-resistant A. baumannii nosocomial infections has not been established. There are no compelling data to recommend combination therapy for severe A. baumannii infections.