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Genome organization of epidemic Acinetobacter baumannii strains

DOI: 10.1186/1471-2180-11-224

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In the present study, we compared whole genome sequences of three A. baumannii strains assigned to genotypes ST2, ST25 and ST78, representative of the most frequent genotypes responsible for epidemics in several Mediterranean hospitals, and four complete genome sequences of A. baumannii strains assigned to genotypes ST1, ST2 and ST77. Comparative genome analysis showed extensive synteny and identified 3068 coding regions which are conserved, at the same chromosomal position, in all A. baumannii genomes. Genome alignments also identified 63 DNA regions, ranging in size from 4 o 126 kb, all defined as genomic islands, which were present in some genomes, but were either missing or replaced by non-homologous DNA sequences in others. Some islands are involved in resistance to drugs and metals, others carry genes encoding surface proteins or enzymes involved in specific metabolic pathways, and others correspond to prophage-like elements. Accessory DNA regions encode 12 to 19% of the potential gene products of the analyzed strains. The analysis of a collection of epidemic A. baumannii strains showed that some islands were restricted to specific genotypes.The definition of the genome components of A. baumannii provides a scaffold to rapidly evaluate the genomic organization of novel clinical A. baumannii isolates. Changes in island profiling will be useful in genomic epidemiology of A. baumannii population.The genus Acinetobacter comprises 26 species with valid names and nine genomic species with provisional designations that were defined by DNA-DNA hybridization. Acinetobacter baumannii, A. pittii and A. nosocomialis are the three species more frequently associated with human diseases [1-3]. A. baumannii is the species that is more frequently isolated in hospitalized patients, especially in intensive-care-unit (ICU) wards. The capability to survive in dry conditions and resistance to disinfectants and antimicrobial agents contribute to the selection of A. baumannii in the


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