Acinetobacter baumannii: emergence of a successful pathogen

Abstract

Acinetobacter baumannii has emerged as a highly troublesome pathogen for many institutions globally. As a consequence of its immense ability to acquire or upregulate antibiotic drug resistance determinants, it has justifiably been propelled to the forefront of scientific attention. Apart from its predilection for the seriously ill within intensive care units, A. baumannii has more recently caused a range of infectious syndromes in military personnel injured in the Iraq and Afghanistan conflicts. This review details the significant advances that have been made in our understanding of this remarkable organism over the last 10 years, including current taxonomy and species identification, issues with susceptibility testing, mechanisms of antibiotic resistance, global epidemiology, clinical impact of infection, host-pathogen interactions, and infection control and therapeutic considerations.

FIG. 1.

Summary of the distribution and genetic context of the OXA-type enzymes in Acinetobacter baumannii. The arrows and corresponding percentages represent the degrees of amino acid homology between the enzyme clusters. The enzyme clusters within large circles signify the acquired enzyme types, in contrast to the naturally occurring OXA-51 cluster within the large square.

FIG. 2.

Countries that have reported an outbreak of carbapenem-resistant Acinetobacter baumannii. Red signifies outbreaks reported before 2006, and yellow signifies outbreaks reported since 2006.