Rapid identification of commonly encountered Candida species directly from blood culture bottles

J Clin Microbiol. 2003 Dec;41(12):5660-4. doi: 10.1128/JCM.41.12.5660-5664.2003.

Abstract

We report a rapid-cycle, real-time PCR method for identifying six Candida spp. directly from BACTEC blood culture bottles. Target sequences in the noncoding internal transcribed spacer regions of the rRNA operon were simultaneously amplified and interrogated with fluorescent probes to identify Candida albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, and C. lusitaniae; these account for 88% of the yeast species isolated from positive blood cultures in our laboratory. Any of the first four species can be identified in a single reaction using two fluorescent hybridization probe sets. The antifungal-resistant species C. krusei and C. lusitaniae are detected in a second reaction, also with two probe sets. The assay was validated with DNA extracted from BACTEC blood culture bottles positive for yeasts (n = 62) and was 100% concordant with culture identification based on biochemical and morphological features of C. albicans (n = 22), C. parapsilosis (n = 10), C. tropicalis (n = 1) C. glabrata (n = 22), C. krusei (n = 2), and C. lusitaniae (n = 1). No cross-reactivity was observed in blood culture samples growing yeasts other than the above-mentioned species (n = 4), in those growing bacteria (n = 12), or in the absence of microbial growth. Our assay allows rapid (</=2 h) and specific detection of the most common Candida spp. directly from positive blood cultures and may facilitate delivery of optimal antifungal therapy.

MeSH terms

  • Algorithms
  • Base Sequence
  • Candida / classification*
  • Candida / growth & development
  • Candida / isolation & purification
  • Candida albicans / classification
  • Candida albicans / isolation & purification
  • Candida glabrata / classification
  • Candida glabrata / isolation & purification
  • Culture Media
  • DNA Primers
  • DNA, Fungal / genetics
  • DNA, Fungal / isolation & purification
  • Gene Amplification
  • Humans
  • Mycology / methods
  • Oligonucleotide Probes
  • Polymerase Chain Reaction / methods

Substances

  • Culture Media
  • DNA Primers
  • DNA, Fungal
  • Oligonucleotide Probes