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Pseudomonas aeruginosa pyocyanin and 1-hydroxyphenazine inhibit fungal growth
J R Kerr1, G W Taylor, A Rutman
1Host Defence Unit, National Heart and Lung Institute, Imperial College, School of Medicine, London, UK.
Aim:
To examine strains of Pseudomonas aeruginosa for specific antifungal factors.
Methods:
Two clinical strains of P aeruginosa with strong in vitro inhibition (by cross streak assay) of Candida albicans and Aspergillus fumigatus were examined. Both strains were isolated from sputum--one from a patient with cystic fibrosis and one from a patient with bronchiectasis. Bacterial extracts were fractionated by high performance liquid chromatography and examined by ultraviolet absorbance and mass spectroscopy. Antifungal activity against C albicans and A fumigatus was determined in a well plate assay.
Results:
Pyocyanin was the major antifungal agent of P aeruginosa; 1-hydroxy-phenazine also possessed activity. Pyocyanin MICs for C albicans and A fumigatus were > 64 micrograms/ml. These phenazines were active against nine other yeast species pathogenic for man. Preliminary experiments also suggested possible inhibition of yeast mycelial transformation in C albicans by pyocyanin.
Conclusions:
There may be a role for pyocyanin and 1-hydroxyphenazine in the prevention of pulmonary candidiasis in patients colonised by P aeruginosa.
Insights
Pseudomonas aeruginosa produces pyocyanin and 1-hydroxyphenazine, which demonstrate significant antifungal activity against Candida albicans and Aspergillus fumigatus. These compounds may help prevent pulmonary candidiasis in susceptible patients.
Area of Science:
- Microbiology
- Medical Mycology
- Pharmacology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Fungal infections, particularly candidiasis, pose a significant threat to immunocompromised individuals.
Purpose of the Study:
- To identify specific antifungal factors produced by Pseudomonas aeruginosa.
- To investigate the potential of these factors in preventing fungal infections.
Main Methods:
- Two clinical strains of P. aeruginosa were analyzed.
- Bacterial extracts were fractionated using HPLC and analyzed via UV absorbance and mass spectroscopy.
- Antifungal activity was assessed against Candida albicans and Aspergillus fumigatus using well plate assays.
Main Results:
- Pyocyanin was identified as the primary antifungal agent in P. aeruginosa.
- 1-hydroxyphenazine also exhibited antifungal properties.
- Both compounds showed activity against C. albicans and A. fumigatus, with MICs > 64 µg/ml, and against nine other human pathogenic yeasts.
Conclusions:
- Pyocyanin and 1-hydroxyphenazine are key antifungal compounds produced by P. aeruginosa.
- These phenazines may play a role in preventing pulmonary candidiasis in patients colonized with P. aeruginosa.