Susceptibility testing of Cryptococcus diffluens against amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole.
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).
Kantarcioğlu
A Serda
AS
Cerrahpasa Medical Faculty, Dept. of Microbiology and Clinical Microbiology, Deep Mycosis Laboratory, Istanbul University, Istanbul, Turkey.
Boekhout
Teun
T
Yücel
Ayhan
A
Altas
Kemal
K
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology*; D003454:Cryptococcus / Q000145:classification / Q000187:drug effects* / Q000254:growth & development; D003470:Culture Media; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology; D005437:Flucytosine / Q000494:pharmacology*; D006801:Humans; D017964:Itraconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D011743:Pyrimidines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D065819:Voriconazole
D000935:Antifungal Agents; D001393:Azoles; D003470:Culture Media; D011743:Pyrimidines; D014230:Triazoles; D017964:Itraconazole; C101425:posaconazole; D000666:Amphotericin B; D015725:Fluconazole; D005437:Flucytosine; D065819:Voriconazole