title: Evaluation of Polymorphic Locus Sequence Typing for Candida glabrata Epidemiology.
abstract: The opportunistic yeast Candida glabratais increasingly refractory to antifungal treatment or prophylaxis and relatedly is increasingly implicated in health care-associated infections. To elucidate the epidemiology of these infections, strain typing is required. Sequence-based typing provides multiple advantages over length-based methods, such as pulsed-field gel electrophoresis (PFGE); however, conventional multilocus sequence typing (targeting 6 conserved loci) and whole-genome sequencing are impractical for routine use. A commercial sequence-based typing service for C. glabratathat targets polymorphic tandem repeat-containing loci has recently been developed. These CgMT-J and CgMT-M services were evaluated with 56 epidemiologically unrelated isolates, 4 to 7 fluconazole-susceptible or fluconazole-resistant isolates from each of 5 center A patients, 5 matched pairs of fluconazole-susceptible/resistant isolates from center B patients, and 7 isolates from a center C patient who responded to then failed caspofungin therapy. CgMT-J and CgMT-M generated congruent results, resolving isolates into 24 and 20 alleles, respectively. Isolates from all but one of the center A patients shared the same otherwise rare alleles, suggesting nosocomial transmission. Unexpectedly, Pdr1 sequencing showed that resistance arose independently in each patient. Similarly, most isolates from center B also clustered together; however, this may reflect a dominant clone since their alleles were shared by multiple unrelated isolates. Although distinguishable by their echinocandin susceptibilities, all isolates from the center C patient shared alleles, in agreement with the previously reported relatedness of these isolates based on PFGE. Finally, we show how phylogenetic clusters can be used to provide surrogate parents to analyze the mutational basis for antifungal resistance.
authors: Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA santosh.katiyar@drexelmed.edu.
authors: Santosh
authors: S
authors: Katiyar
authors: Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
authors: Eric
authors: E
authors: Shiffrin
authors: Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
authors: Celeste
authors: C
authors: Shelton
authors: Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
authors: Kelley
authors: K
authors: Healey
authors: Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
authors: John-Paul
authors: JP
authors: Vermitsky
authors: MicrobiType LLC, Plymouth Meeting, Pennsylvania, USA.
authors: Tom
authors: T
authors: Edlind
mesh_terms: D041221:Candida glabrata / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D002177:Candidiasis / Q000453:epidemiology* / Q000382:microbiology*; D016000:Cluster Analysis; D056426:Genetic Loci; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology / Q000379:methods; D058885:Multilocus Sequence Typing / Q000379:methods*; D016533:Mycological Typing Techniques / Q000379:methods*