Candida albicans strain maintenance, replacement and micro-variation demonstrated by multilocus sequence typing.

Frank Christopher Odds, Amanda Denise Davidson, Mette Dorph Jacobsen, Arianna Tavanti, J. Whyte, C. C. Kibbler, D. Ellis, M. C. Maiden, Duncan James Shaw, Neil Andrew Robert Gow

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Abstract

We typed 165 Candida albicans isolates from 44 different sources by multilocus sequence typing (MLST) and ABC typing of rRNA genes and determined their homozygosity or heterozygosity at the mating-type-like locus (MTL). The isolates represented pairs or larger sets from individual sources, which allowed the determination of strain diversity within patients. A comparison of replicate sequence data determined a reproducibility threshold for regarding isolates as MLST indistinguishable. For 36 isolate sets, MLST and ABC typing showed indistinguishable or highly related strain types among isolates from different sites or from the same site at different times from each patient. This observation included 11 sets with at least one isolate from a blood culture and a nonsterile site from the same patient. For one patient, strain replacement was evidenced in the form of two sets of isolates from different hospital admissions where the strain types within each set were nearly identical but where the two sets differed both by MLST and ABC typing. MLST therefore confirms the existing view of C. albicans strain carriage. Microvariation, evidenced as small differences between MLST types, resulted in most instances from a loss of heterozygosity at one or more of the sequenced loci. Among isolate sets that showed major strain type differences, some isolates could be excluded as likely examples of handling errors during storage. However, for a minority of isolates, intermittent differences in ABC type for tightly clustered MLST types and intermittent appearances of MTL homozygosity lead us to propose that some C. albicans isolates, or all isolates under yet-to-be-determined conditions, maintain a high level of genetic diversity by mechanisms such as recombination, gene conversion, or chromosomal ploidy change.

Original languageEnglish
Pages (from-to)3647-3658
Number of pages11
JournalJournal of Clinical Microbiology
Volume44
DOIs
Publication statusPublished - 2006

Keywords

  • HUMAN-IMMUNODEFICIENCY-VIRUS
  • ENZYME ELECTROPHORESIS ANALYSIS
  • VULVO-VAGINAL CANDIDIASIS
  • POLYMERASE CHAIN-REACTION
  • FLUCONAZOLE-RESISTANT
  • ORAL CANDIDIASIS
  • AIDS PATIENTS
  • MATING-TYPE
  • DRUG-RESISTANCE
  • ANTIFUNGAL SUSCEPTIBILITIES

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