We analyzed data on multilocus sequence typing (MLST), ABC typing, mating type-like locus (MAT) status, and antifungal susceptibility for a panel of 1,391 Candida albicans isolates. Almost all (96.7%) of the isolates could be assigned by MLST to one of 17 clades. eBURST analysis revealed 53 clonal clusters. Diploid sequence type 69 was the most common MLST strain type and the founder of the largest clonal cluster, and examples were found among isolates from all parts of the world. ABC types and geographical origins showed statistically significant variations among clades by univariate analysis of variance, but anatomical source and antifungal susceptibility data were not significantly associated. A separate analysis limited to European isolates, thereby minimizing geographical effects, showed significant differences in the proportions of isolates from blood, commensal carriage, and superficial infections among the five most populous clades. The proportion of isolates with low antifungal susceptibility was highest for MAT homozygous a/a types and then alpha/alpha types and was lowest for heterozygous a/alpha types. The tree of clades defined by MLST was not congruent with trees generated from the individual gene fragments sequenced, implying a separate evolutionary history for each fragment. Analysis of nucleic acid variation among loci and within loci supported recombination. Computational haplotype analysis showed a high frequency of recombination events, suggesting that isolates had mixed evolutionary histories resembling those of a sexually reproducing species.
This work is based on data generated from several projects that were supported by the Wellcome Trust (grants 069615 and 074898), the Ministe`re de la Recherche et de la Technologie (Programme de Recherche Fondamentale en Microbiologie, Maladies Infectieuses et Parasitaires-Re´seau Infections Fongiques), Pasteur Genopole-Ile-deFrance, Merck, Sharp & Dohme, Pfizer UK, the Center for Disease Control, Department of Health, Taiwan (grant DOH94-DC-2011), the National Science Council, Taiwan (grant 94-0324-19-F-00-00-00-35), and the European Commission (Euresfun; grant LSHM-CT-2005-
We are grateful to the many individuals who have supplied us with
the C. albicans isolates, past and present, that formed the experimental material for this study, including J. B. Anderson, G. Chaves, M. Cuenca-Estrella, D. H. Ellis, J.-M. Gomez, G. Haase, M. Hanson, R. Hollis, E. M. Johnson, B. Jones, G. Just, C. C. Kibbler, N. Nolard, M. A. Pfaller, J.-L. Rodriguez-Tudela, J. Schmid, D. R. Soll, D. A. Stevens, F. Symoens, S. Takakura, and K. Y. Yuen. We gratefully acknowledge the skilled technical assistance of Christiane Bouchier, Diana Sharafi, and Julie Whyte. Keith Jolley (University of Oxford) provided valuable guidance in carrying out congruence analysis.
- human pathogen
- European committee
- locus homozygosis
- chromosome loss
- sexual cycle
- opaque cells
- MTL locus