Viable but non-cultivable state: a strategy for Staphylococcus aureus survivable in dual-species biofilms with Pseudomonas aeruginosa?

Accepted ArticleSummary Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent respiratory pathogens in cystic fibrosis (CF) patients. Both organisms often cause chronic and recalcitrant infections, in large part due to their ability to form biofilms, being these mixed-species infections correlated with poor clinical outcomes. In this study, the hypothesis that S. aureus adopts phenotypes allowing its coexistence with P. aeruginosa during biofilm growth was put forward. We noticed that S. aureus undergoes a viable but non-cultivable (VBNC) state in the dominated P. aeruginosa dual-species consortia, whatsoever the strains used to form the biofilms. Moreover, an increased expression of genes associated with S. aureus virulence was detected suggesting that the phenotypic switching to VBNC state might account for S. aureus pathogenicity and, in turn, influence the clinical outcome of the mixed-species infection. Thus, P. aeruginosa seems to induce both phenotypic and transcriptomic changes in S. aureus, helping its survival and co-existence in the dual-species biofilms. Overall, our findings illustrate how interspecies interactions can modulate bacterial virulence in vitro, contributing to a better understanding of the behaviour of P. aeruginosa-S. aureus dual-species biofilms. This article is protected by copyright. All rights reserved.Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020–Programa Operacional Regional do Norte. The authors also acknowledge the support, through the Programa Operacional Competitividade e Internacionalização (COMPETE2020) and by national funds, through the Portuguese Foundation for Science and Technology (FCT), of the POLY-PrevEnTT project (PTDC/BTMSAL/29841/2017-POCI-01-0145-FEDER-029841), and for the Scientific Employment Stimulus 2017 (CEECIND/01507/2017)