title: Fluconazole induces rapid high-frequency MTL homozygosis with microbiological polymorphism in Candida albicans.
abstract: BACKGROUND
  Candida albicans, a common fungal pathogen that can cause opportunistic infections, is regarded as an apparently asexual, diploid fungus. A parasexual cycle was previously found between homozygotes with opposite mating type-like loci (MTLa/α). Fluconazole-resistant strains had a higher proportion of MTL homozygotes, whereas MTL homozygous C. albicans was found in only about 3.2% of clinical strains. MTL heterozygotes had a low frequency (1.4 × 10-4) of white-opaque switching to MTL homozygotes in nature.
  
  
  METHODS
  Here, a reference C. albicans strain (SC5314) was used in a fluconazole-induced assay to obtain standard opaque MTL homozygous strains and first-generation daughter strains from the fluconazole inhibition zone. Further separation methods were employed to produce second- and third-generation daughter strains. Polymerase chain reaction analysis based on MTL genes was used to define MTL genotypes, and microscopic observations, a flow-cytometric assay, and an antifungal E-test were used to compare microbiological characteristics.
  
  
  RESULTS
  MTL homozygotes were found at a high frequency (17 of 35; 48.6%) in fluconazole-induced first-generation daughter strains, as were morphological polymorphisms, decreased DNA content, and modified antifungal drug susceptibility. High-frequency MTL homozygosity was identified inside the fluconazole inhibition zone within 24 hours. The DNA content of fluconazole-induced daughter strains was reduced compared with their progenitor SC5314 and standard MTL homozygous strains.
  
  
  CONCLUSIONS
  Treatment with fluconazole, commonly used to treat invasive candidiasis, inhibited the growth of C. albicans and altered its microbiological characteristics. Our results suggest that fluconazole treatment induces the high frequency of loss of heterozygosity and microbiological polymorphism in C. albicans.
authors.affiliation: Division of Infectious Disease, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Tsong-Yih
authors.initials: TY
authors.lastname: Ou
authors.affiliation: School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Fang-Mo
authors.initials: FM
authors.lastname: Chang
authors.affiliation: Department of Microbiology and Immunology, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wei-Ning
authors.initials: WN
authors.lastname: Cheng
authors.affiliation: School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Adela
authors.initials: A
authors.lastname: Lara
authors.affiliation: Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ming-Li
authors.initials: ML
authors.lastname: Chou
authors.affiliation: School of Dental Technology, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wei-Fang
authors.initials: WF
authors.lastname: Lee
authors.affiliation: Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Kai-Cheng
authors.initials: KC
authors.lastname: Lee
authors.affiliation: School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Che-Tong
authors.initials: CT
authors.lastname: Lin
authors.affiliation: Division of Infectious Disease, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Wen-Sen
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Division of Microbiology, Department of Clinical Laboratory, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Fang-Lan
authors.initials: FL
authors.lastname: Yu
authors.affiliation: Department of Microbiology and Immunology, Taipei Medical University, Taipei, Taiwan. Electronic address: curator@tmu.edu.tw.
authors.forename: Ching-Hua
authors.initials: CH
authors.lastname: Su
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D025141:Drug Resistance, Fungal / Q000235:genetics; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005787:Gene Frequency; D049770:Genes, Mating Type, Fungal / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000187:drug effects / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D015725:Fluconazole
keywords: Candida albicans; fluconazole; loss of heterozygosity; mating type-like gene