Molecular typing of clinical Cryptococcus neoformans isolates collected in Germany from 2004 to 2010

Abstract

Cryptococcosis is a fungal infection mostly caused by Cryptococcus neoformans. We identified agents of cryptococcosis diagnosed in Germany from 2004 to 2010. We used multi-locus sequence typing (MLST) to understand the molecular epidemiology of cryptococcosis. Sero- and mating types of individual patient isolates were determined by PCR. MLST was performed using the seven-locus scheme. Allele and nucleotide diversity was calculated for each locus of C. neoformans var. grubii and C. neoformans var. neoformans. Phylogenetic relations were assessed by dendrograms. Clinical data were compared between infections caused by the two variants. We studied 101 isolates. Eight were identified as hybrids (8%). All non-hybrids were of the α mating type. Among 78 C. neoformans var. grubii (77%), 16 sequence types (STs) were identified including three novel STs. They clustered in four groups, previously isolated in Asia, Europe or worldwide. Among 15 C. neoformans var. neoformans (15%), 10 STs were identified, without clustering. These isolates showed higher allele, and nucleotide diversity compared with C. neoformans var. grubii. C. neoformans var. neoformans was more likely to cause soft-tissue infections (3/9, 33 vs. 1/63, 2%, p = 0.005) and to affect non-AIDS patients (7/14, 50 vs. 15/76, 20%, p = 0.036). C. neoformans var. grubii is the predominant agent of cryptococcosis in Germany. MLST suggests that a part of these cases are acquired abroad by immigrants or tourists. C. neoformans var. neoformans isolates represent a greater genetic diversity and are associated with more variable clinical presentations.