CLINICAL Acinetobacter baumannii ACCESSORY GENOME DIFFERENCES REVEALED BY WHOLE GENOME SEQUENCING

CAMERANESI MM; MORAN BARRIO J; LIMANSKY AS; VIALE AM

Mar del Plata

Congreso; LI Reunión Anual SAIB; 2015

The study of the Acinetobacter baumannii pan-genome, and in particular the accessory genome of phylogenetically-related multidrug-resistant (MDR) clinical strains provides insight into the evolution of antimicrobial resistance in this healthcare-associated opportunistic pathogen. We have conducted a whole genome sequence analysis (WGS) of the phylogenetically related MDR A. baumannii strains Ab244 and Ab242 belonging to ST104 to determine differences in the accessory genome organization which could account for differences in their imipenem susceptibility phenotypes. Ab242 and Ab244 contigs order were inferred using MAUVE with A. baumannii references genomes as blueprints. Both strains shared a high degree of chromosome synteny, but showed differences in the accessory genome. These including i) a 25-kbp plasmid harboring blaOXA-58 and aphA6 genes conferring carbapenem and aminoglycosides resistance, respectively, present only in Ab242; ii) differences in prophage gene content, iii) an island harboring heavy metal resistance genes only in Ab244; and iv) different carO variants encoding outer membrane proteins associated to imipenem uptake. Overall, these observations give evidence of differential gene transfer events and genome reorganization between these strains providing insight into the evolution of resistance determinants among this nosocomial pathogen population.