Pseudomonas aeruginosa is an opportunistic pathogen capable of stably adapting to the antiseptic octenidine by an unknown mechanism. Here we characterise this adaptation, both in the laboratory and a simulated clinical setting, and identify a novel antiseptic resistance mechanism. In both settings, 2 to 4-fold increase in octenidine tolerance was associated with stable mutations and a specific 12 base pair deletion in a putative Tet-repressor family gene (smvR), associated with a constitutive increase in expression of the Major Facilitator Superfamily (MFS) efflux pump SmvA. Adaptation to higher octenidine concentrations led to additional stable mutations, most frequently in phosphatidylserine synthase pssA and occasionally in phosphatidylglycerophosphate synthase pgsA genes, resulting in octenidine tolerance 16- to 256-fold higher than parental strains. Metabolic changes were consistent with mitigation of oxidative stress and altered plasma membrane composition and order. Mutations in SmvAR and phospholipid synthases enable higher level, synergistic tolerance of octenidine.
Bibliographical noteFunding Information: We thank Schülke & Mayr (Norderstedt, Germany) for supplying octenidine and the SEVA community, in particular the group of Victor De Lorenzo, for supplying plasmids and protocols used and adapted in this study. We are grateful to Rose Jeeves for setting up the initial BreSeq analysis workstream. We thank Keith Poole (Queen’s University, Canada) for transposon mutants used in this study. L.J.B., M.E.W. and J.M.S. acknowledge funding from Grant-in-Aid Project number 109506 and M.J.S. from PHE’s Placement Student scheme. P.M.F. is supported by a KCL Health Schools Studentship funded by the EPSRC (EP/M50788X/1). P.F. was supported by a BBSRC LIDo iCASE studentship with Public Health England—2081638. NMR experiments described in this paper were produced using the facilities of the Centre for Biomolecular Spectroscopy, King’s College London, acquired with a Multi-user Equipment Grant from the Wellcome Trust and an Infrastructure Grant from the British Heart Foundation. This work was also supported by the Francis Crick Institute through provision of access to the MRC Biomedical NMR Centre. The Francis Crick Institute receives its core funding from Cancer Research UK (FC001029), the UK Medical Research Council (FC001029), and the Wellcome Trust (FC001029). We thank Dr Tom Frenkiel and Dr Alain Oregioni for their assistance with HR-MAS NMR experiments performed at the Francis Crick Institute. We thank Alice Hodgson-Casson for contributing the metabolic pathway cartoon.
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Publisher Copyright: © Crown 2021
Citation: Bock, L.J., Ferguson, P.M., Clarke, M. et al. Pseudomonas aeruginosa adapts to octenidine via a combination of efflux and membrane remodelling. Commun Biol 4, 1058 (2021).