Evaluation of 4 chromogenic media for detection and identification of clinically relevant yeasts

Abstract number: 1733_661

Ieven M., Wouters Z., Vercauteren E., Goossens H.

Background: Rapid detection and identification of yeasts is essential for an immediate and correct therapeutic management.

Objectives: Four commercially available chromogenic agars for the detection and identification of yeasts were evaluated on strains and directly on clinical specimens.

Methods: A total of 94 well characterised clinical isolates were included (31 C. albicans, 22 C. glabrata, 9 C. parapsilosis, 6 C. krusei, 8 C. tropicalis, 5 C. dubliniensis, 1 C. guilliermondii, 5 Cryptococcus neoformans, 3 Geotrichum spp. and 1 Saccharomyces cerevisiae) as well as 100 clinical specimens, identified positive for yeasts by conventional methods, including a wide range of sample types (wound swabs, sputa, urine blood cultures). All isolates and clinical specimens were cultured onto Candida ID2 (bioMérieux), Oxoid Chromogenic Candida Agar (OCCA, Oxoid) BD CHROMagar Candida (Becton Dickinson) and Cromogen Candida (Biomedics) and examined after both 24 h and 48 h incubation at 37°C or 30°C for the OCCA agar. Conventional non-chromogenic media, commercial identification systems and biochemical tests were used as gold standard to compare the results of the chromogenic media.

Results: The sensitivity for identification of isolates of C. albicans on chromogenic media varied between 13% and 100% after 24 h and increased to 97%-100% for all four media after 48 h. Both BD CHROMagar Candida and OCCA media correctly identified all C. albicans, C. krusei, C. tropicalis and C. dubliniensis after 48 h. Sensitivity for identification of C. glabrata, the second most prevalent species recovered from all clinical specimens, was 100% and 95.5% for OCCA and BD CHROMagar Candida respectively. Specificity for all 4 media was 100%: no single isolate was misidentified. The table presents sensitivity (%) for isolation and identification directly from clinical specimens.

Sensitivity for isolation and identification directly from clinical specimens

Species (n = 114)Sensitivity (%)a
OCCABD CHROMagarCromogen CandidaCandida ID2  
C. albicans91828496
C. glabrata9480NANA
C. krusei100100100100
C. tropicalis100100100NA
C. parapsilosis67NANANA
aNA, not applicable.

Conclusions:C. albicans was detected and identified with the highest sensitivity on the Candida ID2 but the OCCA chromogenic agar allowed to isolate and identify 98.2% of all species isolated from clinical samples with sensitivities varying between 91% and 100%.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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