In Vitro Susceptibility of Dermatophytes to CANCIDAS (Caspofungin Acetate).


Author address: 

Merck & Co. Inc., Rahway, NJ.


Background: The in vitro susceptibility of dermatophytes to caspofungin has not been studied to date. However, currently there are no NCCLS standardized methods for testing the susceptibility of dermatophytes to antifungal agents. Methods: Two methods were utilized in investigating the susceptibility of dermatophytes to caspofungin. One was a modification of the M38-A NCCLS microdilution method for antifungal susceptibility testing of filamentous fungi and a new test that measures whole cell b ?1,3 glucan levels by fluorescence with aniline blue. Results: Four clinical dermatophyte isolates (3 different Trichophyton spp. and 1 Microsporum canis) were tested in vitro for their susceptibility to caspofungin and comparator agents using a modification of the NCCLS method M38A for susceptibility testing of filamentous fungi. Isolates were tested in RPMI medium with starting inocula of 103 microconidia/mL. Comparator agents included griseofulvin, itraconazole, fluconazole and amphotericin B. Minimum inhibitory concentration (MIC) results were read after a 4 day incubation at 35°C. Griseofulvin, itraconazole and fluconazole MICs were read at 80% inhibition while amphotericin B was read at 100% inhibition. The caspofungin MIC was read as the concentration that caused prominent macroscopic and microscopic morphological change in the isolates or Minimum Effective Concentration (MEC as seen with aspergillus spp). Susceptibility results of the comparator drugs were in concordance with previously reported results for these organisms. The MEC for caspofungin for all isolates tested was

abstract No: 


Full conference title: 

43rd Interscience Conference on Antimicrobial Agents
    • ICAAC 43rd