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Suppression of fungal growth exhibited by Pseudomonas aeruginosa
1Department of Bacteriology, Royal Victoria Hospital, Belfast, Northern Ireland.
Abstract:
Three surgery patients were monitored postoperatively, with particular reference to lung infection. In each case there was a clinical impression that Pseudomonas aeruginosa suppressed the growth of Candida albicans in patients with clinically significant lung infections from whom both of these organisms were isolated from serial sputum samples. Regrowth of C. albicans after P. aeruginosa eradication occurred in two patients, despite fluconazole therapy, to which both C. albicans isolates were susceptible. In all three patients, the strain of P. aeruginosa was found to inhibit the growth of the corresponding C. albicans strain in vitro. Further in vitro susceptibility studies revealed significant inhibition by 10 strains of P. aeruginosa of 11 strains of fungi known to infect humans; these were Candida krusei, Candida keyfr, Candida guillermondii, Candida tropicalis, Candida lusitaniae, Candida parapsilosis, Candida pseudotropicalis, Candida albicans, Torulopsis glabrata, Saccharomyces cerevisiae, and Aspergillus fumigatus.
Insights
Pseudomonas aeruginosa was observed to suppress Candida albicans growth in surgery patients with lung infections. This bacterial inhibition occurred even with antifungal treatment, suggesting a direct microbial interaction.
Area of Science:
- Medical Microbiology
- Clinical Infectious Diseases
- Antimicrobial Interactions
Background:
- Postoperative lung infections pose significant clinical challenges.
- Co-infections with bacteria and fungi are common in immunocompromised patients.
- Understanding microbial interactions is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the interaction between Pseudomonas aeruginosa and Candida albicans in postoperative lung infections.
- To determine if Pseudomonas aeruginosa suppresses Candida albicans growth in vivo and in vitro.
- To assess the impact of this interaction on antifungal therapy.
Main Methods:
- Serial sputum sample analysis from three postoperative patients.
- In vitro co-culture experiments of P. aeruginosa and C. albicans strains.
- Antifungal susceptibility testing of Candida isolates.
- In vitro inhibition assays using multiple P. aeruginosa and fungal strains.
Main Results:
- Clinical observation suggested P. aeruginosa suppressed C. albicans growth in three patients.
- C. albicans regrew in two patients despite fluconazole therapy after P. aeruginosa eradication.
- In vitro studies confirmed P. aeruginosa inhibited corresponding C. albicans strains.
- Ten P. aeruginosa strains inhibited 11 human fungal pathogens in vitro.
Conclusions:
- Pseudomonas aeruginosa demonstrates a potent inhibitory effect on Candida species, including Candida albicans.
- This bacterial suppression of fungal growth can occur independently of standard antifungal treatments.
- The findings highlight a significant inter-kingdom microbial antagonism relevant to treating polymicrobial infections.