Which antifungal is considered first-line treatment for systemic candidiasis?

Fluconazole is the first-line treatment for systemic candidiasis primarily because of its efficacy, safety profile, and good bioavailability. It is a triazole antifungal that works by inhibiting the synthesis of ergosterol, a crucial component of fungal cell membranes, leading to increased membrane permeability and ultimately fungal cell death.

In the treatment of systemic candidiasis, especially in immunocompromised patients, fluconazole is often preferred due to its oral bioavailability, which allows for outpatient treatment options. It has a broad spectrum of activity against various Candida species, particularly Candida albicans, and has shown effectiveness in reducing morbidity and mortality associated with fungal infections when used promptly.

Other options presented are not considered first-line for systemic candidiasis. For instance, Amphotericin B is a potent antifungal and has been used for systemic infections but typically is reserved for more severe cases due to its potential nephrotoxicity and the need for intravenous administration. Nystatin is primarily used for oral or superficial candidiasis and is not effective systemically when administered orally since it is not absorbed into the bloodstream. Ampicillin, an antibiotic, does not have antifungal properties and is therefore irrelevant in the treatment of fungal infections.