Objective: Aminocandin (AC) is a new echinocandin undergoing pre-clinical and clinical development. Recently, Candida parapsilosis isolates that are resistant to caspofungin (CAS) have been identified. The purpose of this study was to determine whether AC inhibits CAS-resistant C. parapsilosis in a dose dependent manner, and to compare the effect of AC relative to CAS or micafungin (MFN) on the growth rate of the fungal isolate. Method: One CAS-susceptible C. parapsilosis strain (MIC of 0.5 micrograms/ml) and one strain with an elevated CAS MIC (64 micrograms/ml) were grown in the presence of various concentrations representing 0.5, 1, 2 and 4 times the MIC of AC against each isolate. At predetermined time points (1, 2, 4, 8, 12, 24, 36 and 48 hours) an aliquot was removed and the optical density (OD) read using a spectrophotometer at 420 nm wavelength. Graphs were plotted as OD against time. Growth curves of CAS and MFN at corresponding concentrations were determined as comparators. Results: AC and CAS exerted similar inhibitory effects on the CAS-susceptible strain; 1 microgram/ml (1 x MIC) showed retardation of growth, with recovery of cells by 48 hours. In contrast, AC (1 x MIC) showed twice the inhibitory effect of CAS on the CAS-resistant strain at 48 hours. Comparable inhibitory effect by MFN on both strains was attained only with concentrations of 4 micrograms/ml. Conclusion: Our data show that AC demonstrates potent antifungal activity against C. parapsilosis isolates including those known to have elevated CAS MICs and may indicate that subtle in vitro differences in the activity of different echinocandins may exist. The clinical implications of these findings are yet to be determined.
Full conference title:
16th European Congress of Clinical Microbiology and Infectious Diseases
- ECCMID 16th (2006)