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A comparison of the activity of mepartricin and amphotericin B against yeasts
Abstract:
An in-vitro comparison was made of the activity of mepartricin and amphotericin B against yeasts both in the presence and absence of pooled human plasma. The methods used included minimum inhibitory concentrations (MICs), liquid cultures and scanning electron microscopy (SEM). Mepartricin was found to be consistently more active than amphotericin B and to exhibit a partial inhibitory action over a wider range of concentrations below the MIC. In the presence of plasma, amphotericin B had increased activity but there was a slight reduction for mepartricin. By electron microscopy both drugs exhibited a rapid effect on Candida albicans and the cell membrane was found to be their primary target. Mepartricin was found to have the additional effect of causing a delayed separation of dividing cells and damage on both sides of the septum between mother and daughter cells. This suggests interference with the enzymatic mechanism of septum formation or chitin synthesis.
Insights
Mepartricin demonstrated superior antifungal activity against yeasts compared to amphotericin B in vitro. Mepartricin also showed unique effects on Candida albicans cell division, suggesting novel mechanisms of action.
Area of Science:
- Mycology
- Pharmacology
- Microbiology
Background:
- Antifungal resistance is a growing concern, necessitating the development of new therapeutic agents.
- Amphotericin B is a widely used antifungal, but its efficacy can be affected by plasma.
- Mepartricin is a polyene antifungal agent with potential therapeutic applications.
Purpose of the Study:
- To compare the in vitro antifungal activity of mepartricin and amphotericin B against yeasts.
- To evaluate the impact of human plasma on the activity of both antifungals.
- To investigate the cellular mechanisms of action of mepartricin and amphotericin B using scanning electron microscopy.
Main Methods:
- In vitro susceptibility testing using minimum inhibitory concentrations (MICs).
- Growth inhibition assays in liquid cultures.
- Scanning electron microscopy (SEM) for ultrastructural analysis of yeast cells.
Main Results:
- Mepartricin exhibited greater antifungal activity than amphotericin B across a range of concentrations.
- Amphotericin B's activity increased in the presence of plasma, while mepartricin's activity slightly decreased.
- SEM revealed that both drugs targeted the cell membrane of Candida albicans.
- Mepartricin induced delayed separation of dividing yeast cells and septum damage, suggesting interference with cell wall synthesis.
Conclusions:
- Mepartricin is a potent antifungal agent with broader activity than amphotericin B in vitro.
- Mepartricin possesses unique mechanisms of action, including potential interference with cell division and septum formation.
- Further research into mepartricin's efficacy and safety is warranted for potential clinical applications.