Reduction of the in vivo virulence of Candida albicans by pretreatment with subinhibitory azole concentrations in vitro.

Cells of Candida albicans exposed to subinhibitory concentrations of clotrimazole or bifonazole in shake cultures were found to have a reduced capacity to divide normally or produce germ tubes and mycelia under appropriate conditions, although treated cultures produced a cell mass equivalent to that of the untreated controls. The long-term morphological effects are considered to be due to azole-caused disturbances in ergosterol biosynthesis. When cells, pretreated with subinhibitory concentrations of the azole compounds, were injected intravenously in mice, the resultant infections were of reduced severity in comparison to controls, as measured by mortalities and colony forming units in kidneys.