Susceptibility testing of Cryptococcus diffluens against amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole

TY - JOUR

T1 - Susceptibility testing of Cryptococcus diffluens against amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole

AU - Kantarcioglu, A.S.

AU - Boekhout, T.

AU - Yucel, A.

AU - Altas, K.

N1 - Reporting year: 2009

PY - 2009

Y1 - 2009

N2 - Cryptococcus diffluens is a recently re-established species that shares several phenotypic features with Cryptococcus neoformans. We evaluated the application of the Clinical Laboratory Standards Institute (CLSI, formerly NCCLS) macro- and microbroth dilution methods and the E-test agar diffusion method to determine the in vitro susceptibilities of known strains of C. diffluens against amphotericin B (AMB), flucytosine (5-FC), fluconazole (FLC), itraconazole (ITC) and the novel triazoles, voriconazole (VRC) and posaconazole (PSC). Seven strains were found to be resistant in vitro to AMB (MICs >/=2 microg/ml), five were resistant to 5-FC (MICs of >/=32 microg/ml), four were resistant to FLC (MICs of FLC >/=32 microg/ml) and nine were resistant to ITC (MICs of ITC >1 microg/ml). In contrast, VRC and PSC showed good in vitro activity against C.diffluens strains, even those with elevated MICs to amphotericin B and/or established azoles. Most of the isolates were inhibited by 0.5 microg/ml of both VRC and PSC. A clinical isolate showing phenotypic switching exhibited elevated MICs to both agents, i.e., VRC (>16 microg/ml) and PSC (>8 microg/ml).

AB - Cryptococcus diffluens is a recently re-established species that shares several phenotypic features with Cryptococcus neoformans. We evaluated the application of the Clinical Laboratory Standards Institute (CLSI, formerly NCCLS) macro- and microbroth dilution methods and the E-test agar diffusion method to determine the in vitro susceptibilities of known strains of C. diffluens against amphotericin B (AMB), flucytosine (5-FC), fluconazole (FLC), itraconazole (ITC) and the novel triazoles, voriconazole (VRC) and posaconazole (PSC). Seven strains were found to be resistant in vitro to AMB (MICs >/=2 microg/ml), five were resistant to 5-FC (MICs of >/=32 microg/ml), four were resistant to FLC (MICs of FLC >/=32 microg/ml) and nine were resistant to ITC (MICs of ITC >1 microg/ml). In contrast, VRC and PSC showed good in vitro activity against C.diffluens strains, even those with elevated MICs to amphotericin B and/or established azoles. Most of the isolates were inhibited by 0.5 microg/ml of both VRC and PSC. A clinical isolate showing phenotypic switching exhibited elevated MICs to both agents, i.e., VRC (>16 microg/ml) and PSC (>8 microg/ml).

U2 - 10.1080/13693780802213407

DO - 10.1080/13693780802213407

M3 - Article

SN - 1369-3786

VL - 47

SP - 169

EP - 176

JO - Medical Mycology

JF - Medical Mycology

IS - 2

ER -