Whole Genome Sequence Analysis of the naturally competent Acinetobacter baumannii clinical isolate A118.

TRAGLIA, GERMAN MATIAS; CHUA KATHERINA; CENTRON DANIELA; TOLMASKY MARCELO EDUARDO; RAMIREZ MARIA SOLEDAD

Congreso; ASM metting 2014; 2014

Acinetobacter baumannii infections are of particular concern due to the acquisition of multiple antibiotic resistances. Recent studies have demonstrated a high genomic plasticity in A. baumannii, which may explain its high capacity to acquire multiple antibiotic resistance determinants and to survive in the hospital environment. A. baumannii A118 is naturally competent and susceptible to numerous antibiotics including those commonly used in molecular genetics. These characteristics facilitate its genetic manipulation and therefore make it a convenient laboratory model strain. A118 genome was sequenced on an Illumina IIx genome analyzer. Softwares MAUVE, SplitsTree4, MapSolver, BLAST (version 2.0) and Circos were used for genome analyses. A. baumannii ATCC 17978, AYE and ACICU genomes were used for whole genome comparison. The A118 genome has a 3,824 kbp total length containing 3520 CDS and a 38.4% GC content. Whole genome comparisons (WGC) showed that A118 genome has 98% of average nucleotide identity with the ATCC 17978 strain, which resulted to be the more related sequenced genome. When WGC were carried out against representatives of the most widespread clonal complexes (CC1 and CC2), A118 genome showed 96% of average nucleotide identity with both of them. Mauve WGC identified at least 12 inversions, 250 insertions and 626 deletions comparing with the studied genomes. Multiple differences in gene order were observed among the analyzed strains and at 19 regions, known as locally colinear blocks were identified. We found 43784 (1.1496%), 44130 (1,158%), and 43914 (1,153%) SNPs between A118 and ATCC 17978, AYE, and ACICU strains, respectively. Since A118 possesses the ability to be naturally competent, we also search for the presence of genes that could be involved in natural competence. We found genes comEA, pilQ, pilD, pilF, comL, pilA, comEC, pilI, pilH, pilO, pilN, pilY1(comC), pilE, pilR, and comM, which shared between 94-100% of amino acidic identity to all the annotated A. baumannii genomes. The obtained results revealed a great variability and a dynamic genome organization in the studied strains. We also showed that A118 has most of the genes involved in natural competence. Experimental studies are needed to see the role of each gene in the transformation mechanism.