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Toluidine blue O photodynamic inactivation on multidrug-resistant Pseudomonas aeruginosa
S P Tseng1, L J Teng, C T Chen
1Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan.
Background And Objectives:
Multidrug-resistant (MDR) Pseudomonas aeruginosa infection is becoming a critical problem worldwide. Currently, only limited therapeutic options are available for the treatment of infections caused by MDR P. aeruginosa, therefore, the development of new alternative treatments is needed. Toluidine blue O (TBO) is an effective antibacterial photosensitizing agent against various bacteria. However, reports on antibacterial photosensitization of MDR bacteria are limited. This study aims to determine the in vitro photobactericidal activity of TBO against MDR P. aeruginosa.
Study Design/Materials And Methods:
The efficacy of antibacterial photodynamic inactivation, DNA fragmentation and protein carbonylation of three MDR P. aeruginosa strains and one susceptible strain was compared using TBO as the photosensitizer followed by red light irradiation (630 nm, 90 J/cm(2)) from a light-emitting diode light source. Subsequently, the efficacy of TBO photodynamic inactivation (TBO-PDI) on 60 MDR strains, including 11 with the efflux pump phenotype and 49 with no pump activity, was tested using the minimum lethal drug concentration (MLC) assay.
Results:
TBO-PDI caused similar bactericidal effect (6-7 logs of killing effect), DNA fragmentation and protein carbonylation in three MDR and one susceptible P. aeruginosa strains. Although the TBO accumulation assay indicated that TBO is a substrate for the efflux pump, TBO-PDI produce similar photobactericidal activity against 60 MDR P. aeruginosa strains, either with or without efflux-pump phenotype, and 19 susceptible strains.
Conclusion:
MDR did not affect the susceptibility of P. aeruginosa strains to TBO-PDI. The efflux pump played an insignificant role in TBO-PDI of MDR P. aeruginosa.
Insights
Toluidine blue O photodynamic inactivation (TBO-PDI) effectively kills multidrug-resistant Pseudomonas aeruginosa. This promising antibacterial approach works regardless of efflux pump activity, offering new hope for treating resistant infections.
Area of Science:
- Microbiology
- Photochemistry
- Antimicrobial Resistance
Background:
- Multidrug-resistant (MDR) Pseudomonas aeruginosa infections pose a significant global health threat.
- Limited therapeutic options exist for MDR P. aeruginosa, necessitating novel treatment strategies.
- Toluidine blue O (TBO) is a known antibacterial photosensitizer with potential against resistant bacteria.
Purpose of the Study:
- To evaluate the in vitro photobactericidal activity of TBO against MDR P. aeruginosa.
- To investigate the role of efflux pumps in TBO's efficacy against MDR P. aeruginosa.
Main Methods:
- Compared TBO photodynamic inactivation (TBO-PDI) efficacy, DNA fragmentation, and protein carbonylation in MDR and susceptible P. aeruginosa strains.
- Utilized red light irradiation (630 nm) with TBO as the photosensitizer.
- Assessed TBO-PDI effectiveness on 60 MDR strains (with and without efflux pumps) using minimum lethal drug concentration (MLC) assays.
Main Results:
- TBO-PDI demonstrated a significant bactericidal effect (6-7 log reduction), DNA fragmentation, and protein carbonylation in both MDR and susceptible strains.
- TBO accumulation was affected by efflux pumps, but TBO-PDI efficacy remained consistent across MDR strains, irrespective of efflux pump presence.
- No significant difference in photobactericidal activity was observed between MDR and susceptible P. aeruginosa strains.
Conclusions:
- Multidrug resistance does not impact the susceptibility of P. aeruginosa to TBO-PDI.
- Efflux pumps play a minimal role in the effectiveness of TBO-PDI against MDR P. aeruginosa.
- TBO-PDI represents a viable therapeutic strategy for combating MDR P. aeruginosa infections.
