Species identification of invasive yeasts including Candida in Pakistan: Limitations of phenotypic methods

Joveria Farooqi, Kauser Jabeen, Noureen Saeed, Afia Zafar, Mary Eleanor Brandt, Rumina Hasan

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Objective: To compare phenotypic and genotypic methods of yeast identification. Methods: The in-vitro cross-sectional study was conducted from January 2006 to May 2009. Invasive yeasts isolated at the clinical microbiology laboratory at the Aga Khan University (AKU), Karachi, Pakistan, were identified. Speciation by phenotypic and molecular methods was compared. All yeasts isolated during the study period from blood and other invasive sites were identified using standard methods. Isolates were shipped to Mycotic Diseases Branch, Centres for Disease Control and Prevention, Atlanta, Georgia, USA, for identification by Luminex flow cytometric multianalyte profiling (xMAP) system. Ribosomal ITS2 DNA sequencing was performed on isolates not identified by Luminex. Result: Of the 214 invasive yeasts evaluated, Candida species were 209 (97.7%) while the frequency of non-Candida species was 5 (2.3%). Overall agreement between phenotypic and molecular identification was 81.3%, 90.3% amongst the more common Candida species, and only 38.8% amongst the uncommon yeasts. Conclusion: Phenotypic methods of identification proved adequate for common Candida species, but were deficient in recognising rare Candida and non-Candida yeasts, highlighting the importance of molecular methods for identification.

Original languageEnglish
Pages (from-to)995-998
Number of pages4
JournalJournal of the Pakistan Medical Association
Volume62
Issue number10
Publication statusPublished - Oct 2012

Keywords

  • Candida
  • Cryptococcus
  • Invasive yeasts
  • Luminex MAP
  • Rhodotorula

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