Related Experiment Videos
Abstract:
The synergism of 5-FC with 4 polyene antibiotics, amphotericin B (amph. B), candicidin, trichomycin and nystatin were investigated in 3 in vitro models measuring the fungistatic and fungicidal activity as well as the development of resistant mutants. In these 3 models candicidin and trichomycin exerted a higher synergistic effect than amph. B or nystatin. In vivo (systemic treatment of septicemic candidiasis of the mouse) the combination of 5-FC with amph. B was, however, the most effective. Only with this combination a complete cure (culturally negative) was observed. For topical treatment of Candida vaginitis in rats, the combination of 5-FC with candicidin proved the most active. As far as the biochemical basis of synergism is concerned in Candida albicans in the presence of polyene antibiotics, the incorporation of fluorinated pyrimidines was increased and the reduction of uptake of histidine by 5-FC alone, significantly enhanced. These effects could not be observed in Cryptococcus neoformans. The release of amino acids, phosphate and potassium caused by polyenes was significantly more pronounced in cells pretreated with 5-FC. Thus, the interaction between 5-FC and the polyenes may, in fact be, mutual.
Insights
The combination of 5-fluorocytosine (5-FC) with polyene antibiotics shows synergistic antifungal activity. While candicidin and trichomycin were most effective in vitro, 5-FC with amphotericin B achieved complete cures in systemic candidiasis models.
Area of Science:
- Mycology
- Pharmacology
- Antimicrobial Resistance
Background:
- 5-fluorocytosine (5-FC) is an antifungal agent.
- Polyene antibiotics like amphotericin B disrupt fungal cell membranes.
- Investigating drug combinations is crucial for treating invasive fungal infections.
Purpose of the Study:
- To evaluate the synergistic effects of 5-FC with four polyene antibiotics against Candida species.
- To compare the efficacy of these combinations in vitro and in vivo models.
- To elucidate the biochemical mechanisms underlying the observed synergism.
Main Methods:
- In vitro testing for fungistatic and fungicidal activity.
- Assessment of resistant mutant development.
- In vivo models: systemic candidiasis in mice and topical treatment of Candida vaginitis in rats.
- Biochemical analysis of drug interactions in Candida albicans and Cryptococcus neoformans.
Main Results:
- Candicidin and trichomycin demonstrated higher in vitro synergy with 5-FC compared to amphotericin B and nystatin.
- The combination of 5-FC and amphotericin B was most effective for systemic candidiasis, leading to complete cures.
- 5-FC plus candicidin was the most active topical treatment for Candida vaginitis in rats.
- Biochemically, polyenes enhanced 5-FC's incorporation of fluorinated pyrimidines and histidine uptake inhibition in Candida albicans.
- Polyene-induced release of amino acids, phosphate, and potassium was more pronounced in 5-FC pretreated cells.
Conclusions:
- Synergism between 5-FC and polyene antibiotics is significant and dose-dependent.
- The choice of polyene antibiotic influences the degree of synergism with 5-FC.
- The combination of 5-FC with amphotericin B offers a promising therapeutic strategy for systemic candidiasis.
- The observed biochemical changes suggest a mutual interaction between 5-FC and polyene antibiotics.