Rapid Identification of Cryptococcus neoformans var. grubii, C. neoformans var. neoformans, and C. gattii by Use of Rapid Biochemical Tests, Differential Media, and DNA Sequencing
- 1 July 2011
- journal article
- research article
- Published by American Society for Microbiology in Journal of Clinical Microbiology
- Vol. 49 (7), 2522-2527
- https://doi.org/10.1128/jcm.00502-11
Abstract
Rapid identification of Cryptococcus neoformans var. grubii , Cryptococcus neoformans var. neoformans , and Cryptococcus gattii is imperative for facilitation of prompt treatment of cryptococcosis and for understanding the epidemiology of the disease. Our purpose was to evaluate a test algorithm incorporating commercial rapid biochemical tests, differential media, and DNA sequence analysis that will allow us to differentiate these taxa rapidly and accurately. We assessed 147 type, reference, and clinical isolates, including 6 other Cryptococcus spp. (10 isolates) and 14 other yeast species (24 isolates), using a 4-hour urea broth test (Remel), a 24-hour urea broth test (Becton Dickinson), a 4-hour caffeic acid disk test (Hardy Diagnostics and Remel), 40- to 44-hour growth assessment on l -canavanine glycine bromothymol blue (CGB) agar, and intergenic spacer (IGS) sequence analysis. All 123 Cryptococcus isolates hydrolyzed urea, along with 7 isolates of Rhodotorula and Trichosporon . Eighty-five of 86 C. neoformans (99%) and 26 of 27 C. gattii (96%) isolates had positive caffeic acid results, unlike the other cryptococci (0/10) and yeast species (0/24). Together, these two tests positively identified virtually all C. neoformans/C. gattii isolates (98%) within 4 h. CGB agar or IGS sequencing further differentiated these isolates within 48 h. On CGB, 25 of 27 (93%) C. gattii strains induced a blue color change, in contrast to 0 of 86 C. neoformans isolates. Neighbor-joining cluster analysis of IGS sequences differentiated C. neoformans var. grubii , C. neoformans var. neoformans , and C. gattii . Based on these results, we describe a rapid identification algorithm for use in a microbiology laboratory to distinguish clinically relevant Cryptococcus spp.Keywords
This publication has 27 references indexed in Scilit:
- In Vitro Susceptibility of the Yeast Pathogen Cryptococcus to Fluconazole and Other Azoles Varies with Molecular GenotypeJournal of Clinical Microbiology, 2010
- Emergence and Pathogenicity of Highly Virulent Cryptococcus gattii Genotypes in the Northwest United StatesPLoS Pathogens, 2010
- Correlation of Genotype and In Vitro Susceptibilities of Cryptococcus gattii Strains from the Pacific Northwest of the United StatesJournal of Clinical Microbiology, 2010
- Identification of Cryptococcus gattii by Use of l -Canavanine Glycine Bromothymol Blue Medium and DNA SequencingJournal of Clinical Microbiology, 2009
- The fatal fungal outbreak on Vancouver Island is characterized by enhanced intracellular parasitism driven by mitochondrial regulationProceedings of the National Academy of Sciences of the United States of America, 2009
- Spread ofCryptococcus gattiiinto Pacific Northwest Region of the United StatesEmerging Infectious Diseases, 2009
- Estimation of the current global burden of cryptococcal meningitis among persons living with HIV/AIDSAIDS, 2009
- Consensus multi-locus sequence typing scheme forCryptococcus neoformansandCryptococcus gattiiMedical Mycology, 2009
- Identification of Genotypically Diverse Cryptococcus neoformans and Cryptococcus gattii Isolates by Luminex xMAP TechnologyJournal of Clinical Microbiology, 2007
- Characterization of Environmental Sources of the Human and Animal Pathogen Cryptococcus gattii in British Columbia, Canada, and the Pacific Northwest of the United StatesApplied and Environmental Microbiology, 2007