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Published on: December 28, 2017
In vitro susceptibility of clinical yeast isolates to fluconazole and terconazole
1Medical Mycology Research Center, University of Texas Medical Branch, Galveston 77555-0609, USA.
Objective:
Fifty clinical yeast isolates, representing equally Candida albicans, Candida krusei, Candida parapsilosis, Candida tropicalis, and Torulopsis glabrata, were tested in vitro for their susceptibility to terconazole and fluconazole.
Study Design:
The minimal inhibitory concentrations of terconazole and fluconazole were determined by use of a proposed standardized broth macrodilution assay. Also, the response of selected yeast isolates to 25 micrograms of either drug was measured by agarose disk diffusion experiments.
Results:
For all species the minimum inhibitory concentrations for terconazole were significantly lower than those for fluconazole (p < 0.05). In fact, for each individual isolate the minimum inhibitory concentration of terconazole was consistently lower than that of fluconazole. Differences in the geometric mean of terconazole and fluconazole minimum inhibitory concentrations were largest among C. krusei and T. glabrata, followed by C. parapsilosis, C. tropicalis, and C. albicans, in order of decreasing difference. Disk diffusion experiments suggested that terconazole is a more effective fungistatic agent than fluconazole is.
Conclusion:
Terconazole may be more effective than fluconazole against yeast species other than C. albicans.
Insights
Terconazole demonstrated lower minimum inhibitory concentrations than fluconazole against common yeast species in vitro. This suggests terconazole may be a more effective antifungal agent for certain Candida and Torulopsis glabrata infections.
Area of Science:
- Mycology
- Antimicrobial Susceptibility Testing
- Clinical Microbiology
Background:
- Antifungal resistance is a growing concern in treating yeast infections.
- Fluconazole is a commonly used antifungal, but resistance and variable efficacy exist.
- Evaluating alternative antifungals like terconazole is crucial for effective treatment.
Purpose of the Study:
- To compare the in vitro antifungal activity of terconazole and fluconazole.
- To assess the susceptibility of common clinical yeast isolates to these two antifungal agents.
Main Methods:
- Standardized broth macrodilution assay to determine minimal inhibitory concentrations (MICs).
- Agarose disk diffusion experiments to evaluate fungistatic activity.
- Testing of 50 clinical yeast isolates, including Candida albicans, Candida krusei, Candida parapsilosis, Candida tropicalis, and Torulopsis glabrata.
Main Results:
- Terconazole exhibited significantly lower MICs than fluconazole across all tested yeast species (p < 0.05).
- MICs for terconazole were consistently lower than fluconazole for every individual isolate.
- Disk diffusion assays indicated terconazole as a more potent fungistatic agent compared to fluconazole.
Conclusions:
- Terconazole shows superior in vitro activity compared to fluconazole against several key yeast species.
- Terconazole may offer a more effective therapeutic option for yeast infections caused by species other than Candida albicans.
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