Targeting bioenergetics is key to counteracting the drug-tolerant state of biofilm-grown bacteria
Open Access
- 22 December 2020
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLoS Pathogens
- Vol. 16 (12), e1009126
- https://doi.org/10.1371/journal.ppat.1009126
Abstract
Embedded in an extracellular matrix, biofilm-residing bacteria are protected from diverse physicochemical insults. In accordance, in the human host the general recalcitrance of biofilm-grown bacteria hinders successful eradication of chronic, biofilm-associated infections. In this study, we demonstrate that upon addition of promethazine, an FDA approved drug, antibiotic tolerance of in vitro biofilm-grown bacteria can be abolished. We show that following the addition of promethazine, diverse antibiotics are capable of efficiently killing biofilm-residing cells at minimal inhibitory concentrations. Synergistic effects could also be observed in a murine in vivo model system. PMZ was shown to increase membrane potential and interfere with bacterial respiration. Of note, antibiotic killing activity was elevated when PMZ was added to cells grown under environmental conditions that induce low intracellular proton levels. Our results imply that biofilm-grown bacteria avoid antibiotic killing and become tolerant by counteracting intracellular alkalization through the adaptation of metabolic and transport functions. Abrogation of antibiotic tolerance by interfering with the cell’s bioenergetics promises to pave the way for successful eradication of biofilm-associated infections. Repurposing promethazine as a biofilm-sensitizing drug has the potential to accelerate the introduction of new treatments for recalcitrant, biofilm-associated infections into the clinic. At sub-minimal inhibitory concentrations, phenothiazines have been shown to inhibit virulence as well as the formation of biofilms in a wide range of different bacterial pathogens. In this study, we analyzed the anti-bacterial effect of the FDA-approved drug, promethazine, on biofilm-grown Pseudomonas aeruginosa. We demonstrate that PMZ interferes with bacterial bioenergetics and sensitizes biofilm-grown P. aeruginosa cells to bactericidal activity of several different classes of antibiotics by several orders of magnitude. This effect was most pronounced when cells were grown under environmental conditions that induce low intracellular proton levels. Thus, it seems that a reduced proton efflux in cells that exhibit decreased respiratory activity due to their biofilm mode of growth might explain their general antimicrobial tolerance. The use of PMZ as an antibiotic sensitizer holds promise that targeting tolerance mechanisms of biofilm-grown bacteria could become a practicable way to change the way physicians treat biofilm-associated infections.Keywords
Funding Information
- European Research Council (COMBAT 724290)
- Deutsche Forschungsgemeinschaft (EXC 2155 “RESIST” – Project ID 39087428)
This publication has 88 references indexed in Scilit:
- A Dysfunctional Tricarboxylic Acid Cycle Enhances Fitness of Staphylococcus epidermidis During β-Lactam StressmBio, 2013
- Starvation, Together with the SOS Response, Mediates High Biofilm-Specific Tolerance to the Fluoroquinolone OfloxacinPLoS Genetics, 2013
- Discovery of Antagonists of PqsR, a Key Player in 2-Alkyl-4-quinolone-Dependent Quorum Sensing in Pseudomonas aeruginosaCell Chemical Biology, 2012
- Metabolic Regulation of Mycobacterial Growth and Antibiotic SensitivityPLoS Biology, 2011
- A Novel In Vitro Multiple-Stress Dormancy Model for Mycobacterium tuberculosis Generates a Lipid-Loaded, Drug-Tolerant, Dormant PathogenPLOS ONE, 2009
- Genomewide Identification of Genetic Determinants of Antimicrobial Drug Resistance inPseudomonas aeruginosaAntimicrobial Agents and Chemotherapy, 2009
- Inactivation of Efflux Pumps Abolishes Bacterial Biofilm FormationApplied and Environmental Microbiology, 2008
- Novel Genetic Determinants of Low-Level Aminoglycoside Resistance in Pseudomonas aeruginosaAntimicrobial Agents and Chemotherapy, 2008
- RamA Confers Multidrug Resistance in Salmonella enterica via Increased Expression of acrB , Which Is Inhibited by ChlorpromazineAntimicrobial Agents and Chemotherapy, 2008
- The Pseudomonas Quinolone Signal (PQS) Balances Life and Death in Pseudomonas aeruginosa PopulationsPLoS Pathogens, 2008