Influence of temperature and concentration on the postantifungal effect and the effects of sub-MIC concentrations of four antifungal agents on previously treated Candida species

Background: The objective of this study was to investigate the impact of di fferent temperatures (22, 35 and 37 degrees C) on the postantifungal effect (PAFE) and the effect of sub-MIG concentrations (1/4 x MIC) on Candida alb icans and Candida glabrata in PAFE stage (PAFSE). Methods: This stage was i nduced by a 1.5-hour pretreatment with different doses (1 x,4 x and 8 x MIG ) of four antifungal agents that are fundamental to modern candidiasis ther apy. Results: The temperature, as well as the dose of the antifungal agent that was applied during the pretreatment, determined the duration of the tw o studied effects. An increase in the temperature and/or the dose prolonged the duration of the PAFE and PAFSE in both species, independent of the app lied antifungal agent. Amphotericin B and 5-fluorocytosine always induced s ignificant PAFEs (0.5-4.8 h and 0.5-3.0 h, respectively), which were increa sed (0.7-3.4 h and 0.5-3.2 h, respectively) by posterior exposure to 1/4 x MIC of the respective antifungal agent. in the case of ketoconazole and flu conazole, temperature and concentration were especially important. Although neither antimycotics was able to induce a significant PAFE, posterior expo sure to 1/4 x MIC of each of the two azoles led in both yeast species to a significant PAFSE of up to 0.8 h (if the concentrations and/or the temperat ures were high enough). Conclusion: factors such as temperature and concent ration could be important when choosing an antifungal agent. Copyright (C) 2000 S. Karger AG. Basel.