[Rational use of antimycotics against yeast infections]

In clinical medicine mere colonization with yeasts is often hardly to be discriminated from true infection. Thus, a clear-cut separation of preventive from therapeutic use of antimycotics is not possible in practical medicine. The problem is that on the one hand one has no exact diagnosis of yeast infection, but on the other hand best therapeutic results are obtained when the drugs are given as early as possible. In comparison to the huge number of antibacterial compounds, the members of antimicrobials are limited. For prophylaxis, one can use the polyenes, such as amphotericin B and nystatin, or the azoles, such as fluconazole or itraconazole. Thereby the azoles act not only locally at the site of application but are absorbed and thus are distributed to remote sites, where the non-resorbable polyenes never arrive. Among the azoles, fluconazole has the advantage that resorption is independent from an acid pH in the stomach, whereas itraconazole resorption is variable in severely ill persons with neutralized gastric fluid. For therapeutic use systemically applied amphotericin B has certain disadvantages. Because of toxic reactions an optimal dose cannot be given; furthermore in some sites insufficient concentrations are achieved, particularly in the kidney and also in the CSF. In contrast, the azoles possess better pharmacologic and toxicologic properties. Resistance to antimycotics is principally possible but still rare, so that in practice a routine testing is not necessary. Candida glabrata as well as Candida krusei are primarily resistant to fluconazole.