Azole antifungal agents: Emerging and inherent resistance

The development of resistance to azole antifungals in yeasts is a recent phenomenon. It is usually described for Candida albicans and fluconazole in oropharyngeal and oesophageal candidiasis in advanced stages of AIDS. The cross resistance between the triazoles fluconazole and itraconazole is frequent, but not constant, and the decrease in susceptibility is of the same order of magnitude for both triazoles. Candida krusei and Candida (Torulopsis) glabrata are intrinsically resistant to these triazoles. The most important mechanisms of resistance are a reduced permeability of the cell membrane and a mutation in the target fungal enzyme cytochrome p450. The wide use of the new azoles can increase the colonization and the infection rate with resistant species in compromised patients. An epidemiological survey of clinical response and susceptibility pattern of Candida is necessary in HIV-positive and HIV-negative patients.