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Updated: May 17, 2026
Live/Dead Staining for Quantifying Viable but Not Culturable Cells in Manuka Honey-Treated Wound-Causing Bacteria
Published on: April 25, 2025
Manuka honey is bactericidal against Pseudomonas aeruginosa and results in differential expression of oprF and algD
Aled E L Roberts1, Sarah E Maddocks1, Rose A Cooper1
1Cardiff Metropolitan University, Western Avenue, Cardiff CF5 2YB, UK.
Abstract:
The presence of Pseudomonas aeruginosa in cutaneous wounds is of clinical significance and can lead to persistent infections. Manuka honey has gained ground in clinical settings due to its effective therapeutic action and broad spectrum of antibacterial activity. In this study, the effect of manuka honey on P. aeruginosa was investigated using MIC, MBC, growth kinetics, confocal microscopy, atomic force microscopy and real-time PCR. A bactericidal mode of action for manuka honey against P. aeruginosa was deduced (12 %, w/v, MIC; 16 %, w/v, MBC) and confirmed by confocal and atomic force microscopy, which showed extensive cell lysis after 60 min exposure to inhibitory concentrations of manuka honey. The inability of honey-treated cells to form microcolonies was demonstrated and investigated using Q-PCR for three key microcolony-forming genes: algD, lasR and oprF. The expression of algD increased 16-fold whereas oprF expression decreased 10-fold following honey treatment; lasR expression remained unaltered. These findings confirm that manuka honey is effective at inducing cell lysis and identify two targets, at the genetic level, that might be involved in this process.
Insights
Manuka honey effectively kills Pseudomonas aeruginosa by causing cell lysis, with significant changes in algD and oprF gene expression. This demonstrates its potential as a therapeutic agent for wound infections.
Area of Science:
- Microbiology
- Biochemistry
- Medical Science
Background:
- Pseudomonas aeruginosa is a significant pathogen in cutaneous wound infections.
- Manuka honey possesses broad-spectrum antibacterial properties and therapeutic efficacy.
Purpose of the Study:
- To investigate the antibacterial effects of manuka honey on Pseudomonas aeruginosa.
- To elucidate the mechanism of action of manuka honey against P. aeruginosa at the cellular and genetic levels.
Main Methods:
- Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays.
- Confocal and atomic force microscopy for cell morphology analysis.
- Quantitative real-time PCR (Q-PCR) to assess gene expression (algD, lasR, oprF).
Main Results:
- Manuka honey exhibited bactericidal activity with MIC at 12% (w/v) and MBC at 16% (w/v).
- Microscopy revealed extensive cell lysis in P. aeruginosa after 60 minutes of exposure to manuka honey.
- Q-PCR showed a 16-fold increase in algD expression and a 10-fold decrease in oprF expression, while lasR remained unchanged.
Conclusions:
- Manuka honey induces significant cell lysis in Pseudomonas aeruginosa.
- The study identifies algD and oprF as potential genetic targets involved in manuka honey's bactericidal action against P. aeruginosa.
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