Decreased efficacy of antimicrobial agents in a polymicrobial environment.


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Authors
Abstract

The airways of people with cystic fibrosis (CF) often harbour diverse polymicrobial communities. These airway infections can be impossible to resolve through antibiotic intervention, even though isolates of the individual species present are susceptible to the treatment when tested in vitro. In this work, we investigate how polymicrobial cultures comprised of key CF-associated pathogens respond to challenge with species-specific antimicrobial agents; colistin (targets Pseudomonas aeruginosa), fusidic acid (targets Staphylococcus aureus), and fluconazole (targets Candida albicans). We found that growth in a polymicrobial environment protects the target microorganism (sometimes by several orders of magnitude) from the effect(s) of the antimicrobial agent. This decreased antimicrobial efficacy was found to have both non-heritable (physiological) and heritable (genetic) components. Whole-genome sequencing of the colistin-resistant P. aeruginosa isolates revealed single nucleotide polymorphisms and indels in genes encoding lipopolysaccharide (LPS) biosynthesis and/or pilus biogenesis, indicating that a previously undescribed colistin resistance mechanism was in operation. This was subsequently confirmed through further genetic analyses. Our findings indicate that the polymicrobial nature of the CF airways is likely to have a significant impact on the clinical response to antimicrobial therapy.

Description

Funder: Cystic Fibrosis Trust (CF); doi: https://doi.org/10.13039/501100000292


Funder: British Lung Foundation (BLF); doi: https://doi.org/10.13039/501100000351

Keywords
Anti-Bacterial Agents, Anti-Infective Agents, Colistin, Cystic Fibrosis, Humans, Pseudomonas Infections, Pseudomonas aeruginosa, Staphylococcus aureus
Journal Title
ISME J
Conference Name
Journal ISSN
1751-7362
1751-7370
Volume Title
16
Publisher
Springer Science and Business Media LLC
Sponsorship
National Centre for the Replacement Refinement and Reduction of Animals in Research (NC/P001564/1)