Impact of rapid identification of C. albicans and C. glabrata directly from blood cultures using PNA FISH technology on selection of antifungal therapy

Abstract number: P1382

Della-Latta P., Whittier S., Wu F.

Objectives: We studied the performance of the peptide nucleic acid fluorescent in situ hybridisation (PNA FISH) assay for rapid identification of Candida albicans and Candida glabrata directly from blood cultures within hours, compared to routine methods with time to results at 1 to 2 days. The impact of differentiating these 2 species in real time on the selection of or change to the most effective antifungal treatment (Tx) was evaluated. Our 2007 antibiogram demonstrated that fluconazole (FLU) susceptibility for isolates of C. albicans and C. parapsilosis was nearly 100%; FLU resistance was 21%, 50% and 10%, for C. glabrata, C. krusei and C. tropicalis, respectively. The emerging resistance to FLU in non-albicans strains and their predictable susceptibility to caspofungin (CP) often results in empiric Tx with CP.

Methods: 37 blood cultures newly Gram stain positive for yeast were evaluated for the presence of either C. albicans or C. glabrata or neither by PNA FISH (AdvanDx, Woburn, MA) technology. The assay uses fluorophore-labeled dual probes with staining green for C. albicans and red for C. glabrata. Routine identification was performed using MicroScan panels (Dade Behring, Sacramento CA) and CHROMagar selective media (BD, Sparks, MD).

Results: The Candida spp. recovered included 15 C. glabrata, 10 C. albicans, 5 C. parapsilosis, 2 C. tropicalis, 1 C. krusei, and 1 Candida dubliniensis. The sensitivity, specificity, positive and negative predictive values of PNA FISH for C. glabrata and C. albicans compared to routine identification methods were 100%. One patient isolate negative by FISH and presumptively positive for C. albicans by CHROMagar was identified as C. dubliniensis, a strain known to develop resistance to FLU. Tx of 7/15 patients (47%) with C. glabrata sepsis, was changed from FLU to CP within hours of reporting FISH results; for 2/10 patients (20%) with C. albicans fungaemia CP was switched to FLU after rapid reporting.

Conclusions: The PNA FISH accurately identifies C. albicans and C. glabrata directly from positive blood cultures within hours and can impact on the appropriate selection of the most effective antifungal Tx, thereby making it a clinically relevant diagnostic assay.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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