Treating Extensively Drug-Resistant Acinetobacter baumannii: Considerations for Host Characteristics and Type of Infections

<i>Acinetobacter baumannii</i> has been characterized by CDC, WHO and most National Healthcare Systems worldwide as a critical nosocomial pathogen, and classified as an ESKAPE (<i>Enterococcus faecium</i>, <i>Staphylococcus aureus</i>, <i>Klebsiella pneumoniae</i>, <i>Acinetobacter baumannii</i>, <i>Pseudomonas aeruginosa</i>, <i>Enterobacter</i> spp.) pathogen. Mortality of invasive infections due to <i>A. baumannii</i> exceeds 40%. To highlight its impact on public health, ECDC has organized a special project on national lab co-ordination to accurately detect and report carbapenem-resistant strains, to identify epidemiological factors for infection (or colonization) with carbapenem-resistant <i>A. baumanii</i> at clonal and sub-genomic level. This review aims to describe the history, epidemiology, and evolution of resistance of <i>A. baumannii</i>, and stress the caveats associated with the management of systemic infections. Available active antimicrobials and drugs in the pipeline are listed, and available clinical evidence on their pharmacokinetics and efficacy in various types of infections are described. Clinician's choice of treatment (drug, and monotherapy vs. combination treatment) depends on the patients' profile, site of infection and antimicrobial resistance profile. Emphasis is laid on specific patient subpopulations, whose management is discussed.