Extensive genetic diversity within the Dutch clinical Cryptococcus neoformans population.

A set of 300 Dutch Cryptococcus neoformans isolates, obtained from 237 patients during 1977 to 2007, was investigated by determining the mating type, serotype, and AFLP and microsatellite genotype and susceptibility to seven antifungal compounds. Almost half of the studied cases were from HIV-infected patients, followed by a patient group of individuals with other underlying diseases and immunocompetent individuals. The majority of the isolates were mating type α and serotype A, followed by αD isolates and other minor categories. The most frequently observed genotype was AFLP1, distantly followed by AFLP2 and AFLP3. Microsatellite typing revealed a high genetic diversity among serotype A isolates but a lower diversity within the serotype D set of isolates. One patient was infected by multiple AFLP genotypes. Fluconazole and flucytosine had the highest geometric mean MICs of 2.9 and 3.5 µg/ml, respectively, while amphotericin B (0.24 µg/ml), itraconazole (0.08 µg/ml), voriconazole (0.07 µg/ml), posaconazole (0.06 µg/ml), and isavuconazole (0.03 µg/ml) had much lower geometric mean MICs. One isolate had a high flucytosine MIC (>64 µg/ml), while decreased susceptibility (≥16 µg/ml) for flucytosine and fluconazole was found in 9 and 10 C. neoformans isolates, respectively.

In vitro antifungal susceptibilities and molecular typing of sequentially isolated clinical Cryptococcus neoformans strains from Croatia.

A collection of 48 clinical Cryptococcus neoformans isolates from Croatia was investigated retrospectively using in vitro antifungal susceptibility testing and molecular biological techniques to determine mating type and serotype by PCR and amplified fragment length polymorphism (AFLP) genotyping. These isolates were obtained from 15 patients: ten were human immunodeficiency virus (HIV)-negative (66.7 %) and five were HIV-positive (33.3 %). From five patients, only one isolate was available, whilst from the other ten patients, two to 11 isolates were isolated sequentially. Antifungal susceptibility was tested by a broth microdilution method. Serotype A (genotype AFLP1) and serotype D (genotype AFLP2) were both found in six patients (40 % each), and serotype AD (genotype AFLP3) in three (20.0 %) patients. Mating type α (n = 12; 80.0 %) predominated and α/a hybrids were identified in 20.0 % of patients diagnosed with cryptococcosis. Two AFLP genotypes of C. neoformans were isolated during a single episode from one patient. The in vitro antifungal MIC(90) and susceptibility ranges for C. neoformans isolates were 0.5 µg ml(-1) (range 0.031-0.5 µg ml(-1)) for amphotericin B, 4 µg ml(-1) (range 1-4 µg ml(-1)) for flucytosine and fluconazole, 0.25 µg ml(-1) (range 0.031-0.5 µg ml(-1)) for itraconazole and 0.062 µg ml(-1) (range 0.031-0.25 µg ml(-1)) for voriconazole.