ABSTRACT
The synthesis and antifungal activity of ASP9726, a novel echinocandin with potent Aspergillus hyphal growth inhibition and significantly improved MIC against Candida parapsilosis and echinocandin resistant-Candida is described.
Subject(s)
Antifungal Agents/pharmacology , Aspergillus/drug effects , Echinocandins/pharmacology , Antifungal Agents/chemical synthesis , Antifungal Agents/chemistry , Aspergillus/growth & development , Dose-Response Relationship, Drug , Echinocandins/chemical synthesis , Echinocandins/chemistry , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity RelationshipABSTRACT
We report the appearance of Candida glabrata strains with reduced sensitivity during treatment with the echinocandin drug micafungin (MCF). Four C. glabrata strains were isolated from sputum, gastric juice, and blood taken from a patient during hospitalization. Two of these strains, one of which was obtained after treatment with MCF for suspected Candida pneumonia and the other of which was obtained during MCF treatment for candidemia, were isolated from blood and found to have a reduced susceptibility to MCF. These two clinical isolates showed a high minimum inhibitory concentration (MIC) for MCF, with this change in MIC being unique for MCF among established antifungal drugs. To further investigate the mechanism underlying this reduced sensitivity, an in vivo mouse infection model and in vitro enzymatic analysis were performed. MCF had little effect in the mouse disseminated infection model and enzymatic analysis showed the low affinity of MCF to the 1,3-Beta-D-glucan synthase of the clinical isolates, although the enzymes of both clinical isolates and control strain were noncompetitively inhibited by MCF. Taken together, this low affinity of MCF for the enzymes is likely to cause the reduced sensitivities. These data further indicate that MCF could induce acquired MCF-resistant strains during clinical use.