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Front. Microbiol. | doi: 10.3389/fmicb.2019.02429

In vitro and in vivo virulence potential of the emergent species of the Acinetobacter baumannii (Ab) group

 Clara Cosgaya1,  Carlos Ratia1, Marta Marí-Almirall1, Laia Rubio1,  Paul G. Higgins2, Harald Seifert2, Ignasi Roca Subirà1* and  Jordi Vila1
  • 1Instituto Salud Global Barcelona (ISGlobal), Spain
  • 2Institute of Medical Microbiology, Immunology and Hygiene, University Hospital Cologne, Germany

The increased use of molecular identification methods and mass spectrometry has revealed that Acinetobacter spp. of the A. baumannii (Ab) group other than A. baumannii 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 (A. baumannii n=16, A. lactucae n=12, A. nosocomialis n=16, A. pittii n=20, and A. seifertii n=12), were compared in terms of antimicrobial susceptibility, carriage of intrinsic resistance genes, biofilm formation, and the ability to kill Caenorhabditis elegans in an infection assay. In agreement with previous studies, antimicrobial resistance was common among A. baumannii 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 A. baumannii, A. lactucae (heterotypic synonym of A. dijkshoorniae) and A. pittii but not in A. nosocomialis and A. seifertii. A. baumannii and A. nosocomialis presented weaker pathogenicity in our in vitro and in vivo models than A. seifertii, A. pittii and, especially, A. lactucae. Isolates from the former species showed decreased biofilm formation and required a longer time to kill C. elegans 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.

Keywords: Acinetobacter, multi-drug resistance, Virulence, Biofilm formation, C. elegans, efflux pumps, Oxacillinases

Received: 18 Jun 2019; Accepted: 08 Oct 2019.

Copyright: © 2019 Cosgaya, Ratia, Marí-Almirall, Rubio, Higgins, Seifert, Roca Subirà and Vila. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Ignasi Roca Subirà, Instituto Salud Global Barcelona (ISGlobal), Barcelona, 08003, Catalonia, Spain, IGROCA@clinic.ub.es