AUTHOR=Cosgaya Clara , Ratia Carlos , Marí-Almirall Marta , Rubio Laia , Higgins Paul G. , Seifert Harald , Roca Ignasi , Vila Jordi 

TITLE=In vitro and in vivo Virulence Potential of the Emergent Species of the Acinetobacter baumannii (Ab) Group

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.02429

DOI=10.3389/fmicb.2019.02429

ISSN=1664-302X

ABSTRACT=<p>The increased use of molecular identification methods and mass spectrometry has revealed that <italic>Acinetobacter</italic> spp. of the <italic>A. baumannii</italic> (Ab) group other than <italic>A. baumannii</italic> are increasingly being recovered from human samples and may pose a health challenge if neglected. In this study 76 isolates of 5 species within the Ab group (<italic>A. baumannii n</italic> = 16, <italic>A. lactucae n</italic> = 12, <italic>A. nosocomialis n</italic> = 16, <italic>A. pittii n</italic> = 20, and <italic>A. seifertii n</italic> = 12), were compared in terms of antimicrobial susceptibility, carriage of intrinsic resistance genes, biofilm formation, and the ability to kill <italic>Caenorhabditis elegans</italic> in an infection assay. In agreement with previous studies, antimicrobial resistance was common among <italic>A. baumannii</italic> while all other species were generally more susceptible. Carriage of genes encoding different efflux pumps was frequent in all species and the presence of intrinsic class D β-lactamases was reported in <italic>A. baumannii</italic>, <italic>A. lactucae</italic> (heterotypic synonym of <italic>A. dijkshoorniae</italic>) and <italic>A. pittii</italic> but not in <italic>A. nosocomialis</italic> and <italic>A. seifertii</italic>. <italic>A. baumannii</italic> and <italic>A. nosocomialis</italic> presented weaker pathogenicity in our <italic>in vitro</italic> and <italic>in vivo</italic> models than <italic>A. seifertii</italic>, <italic>A. pittii</italic> and, especially, <italic>A. lactucae</italic>. Isolates from the former species showed decreased biofilm formation and required a longer time to kill <italic>C. elegans</italic> nematodes. These results suggest relevant differences in terms of antibiotic susceptibility patterns among the members of the Ab group as well as highlight a higher pathogenicity potential for the emerging species of the group in this particular model. Nevertheless, the impact of such potential in the human host still remains to be determined.</p>