Susceptibility Patterns of Candida Tropicalis (CT) Against Eight Antifungals.

M. W. HO1,2, D. I. MCCARTHY 1, A. W. FOTHERGILL 1, N. NAJARIAN 3, M. G. RINALDI 1, T. F. PATTERSON 1, J. R. GRAYBILL 1;

Author address: 

1UTHSCSA, San Antonio, TX, 2China Med. Univ. Hosp., Taichung, Taiwan, 3Indevus, Lexington, MA.

Abstract: 

Background: CT is a common fungal pathogen, but there are few data comparing in vitro susceptibility of CT. We evaluated 8 antifungals against CT: amphotericin B (AMB), fluconazole (FCZ), voriconazole (VORI), posaconazole (POS), anidulafungin (ANFG), caspofungin (CAS), micafungin (MICA) and the investigational echinocandin, aminocandin (AC, Indevus, Lexington, MA), AC. Methods: CLSI M27-A2 was used to test 100 consecutive clinical isolates of CT. AMB was tested in antibiotic medium 3 (M3). Azoles were tested in RPMI. Echinocandins were tested in both M3 and RPMI. Endpoints were determined spectrophotometrically at 50% inhibition in RPMI and 100% inhibition in M3. Results: When tested in M3, all but one 24/48 hr readings fell within 2 dilutions of each other for all drugs. As a result of trailing, drugs tested in RPMI, tended to have a greater difference between 24/48 h readings. The 48 h MICs, geometric mean and MIC range (μg/ml) were: AC, ANFG, CAS and MICA MICs were 3.2±1.8, 0.3±0.7, 3.3±1.7 and 0±0.2 (mean ± SD) dilutions lower in M3 than RPMI respectively. For isolates with high MICs to a drug, high MICs were also observed to other agents within the class. High MICs across the classes was not noted. Conclusions: POS had the lowest MIC among 3 azoles tested. All 4 echinocandins had similar MICs in M3. RPMI produced higher MICs for CAS and AC compared to M3 but not for MICA or ANFG. Echinocandin resistance in CT was detected but was uncommon with either method. In vivo studies are needed to evaluate the relevance of culture media on in vitro susceptibility.
2006

abstract No: 

M-1585

Full conference title: 

46th Interscience Conference on Antimicrobial Agents and Chemotherapy
    • ICAAC 46th