title: Phylogenetic and genomic diversity in isolates from the globally distributed Acinetobacter baumannii ST25 lineage.
abstract: Acinetobacter baumannii is a globally distributed nosocomial pathogen that has gained interest due to its resistance to most currently used antimicrobials. Whole genome sequencing (WGS) and phylogenetics has begun to reveal the global genetic diversity of this pathogen. The evolution of A. baumannii has largely been defined by recombination, punctuated by the emergence and proliferation of defined clonal lineages. In this study we sequenced seven genomes from the sequence type (ST)25 lineage and compared them to 12 ST25 genomes deposited in public databases. A recombination analysis identified multiple genomic regions that are homoplasious in the ST25 phylogeny, indicating active or historical recombination. Genes associated with antimicrobial resistance were differentially distributed between ST25 genomes, which matched our laboratory-based antimicrobial susceptibility typing. Differences were also observed in biofilm formation between ST25 isolates, which were demonstrated to produce significantly more extensive biofilm than an isolate from the ST1 clonal lineage. These results demonstrate that within A. baumannii, even a fairly recently derived monophyletic lineage can still exhibit significant genotypic and phenotypic diversity. These results have implications for associating outbreaks with sequence typing as well as understanding mechanisms behind the global propagation of successful A. baumannii lineages.
authors.affiliation: Translational Genomics Research Institute, Flagstaff, AZ, USA.|Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ, USA.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Sahl
authors.affiliation: Department of Public Health, University of Naples "Federico II", Naples, Italy.
authors.forename: Mariateresa
authors.initials: M
authors.lastname: Del Franco
authors.affiliation: Department of Microbiology, Medical School, University of Athens, Athens, Greece.
authors.forename: Spyros
authors.initials: S
authors.lastname: Pournaras
authors.affiliation: Translational Genomics Research Institute, Flagstaff, AZ, USA.
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Colman
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Nabil
authors.initials: N
authors.lastname: Karah
authors.affiliation: Department of Infectious Diseases, Leiden University Medical Centre, Leiden, The Netherlands.
authors.forename: Lenie
authors.initials: L
authors.lastname: Dijkshoorn
authors.affiliation: Department of Public Health, University of Naples "Federico II", Naples, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Zarrilli
mesh_terms: D040981:Acinetobacter baumannii / Q000145:classification* / Q000235:genetics*; D005075:Biological Evolution; D004269:DNA, Bacterial / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D016680:Genome, Bacterial / Q000235:genetics*; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D013045:Species Specificity
chemical_list: D004269:DNA, Bacterial