Blood culture remains the gold standard, for invasive yeast infection diagnosis, despite its low sensitivity. Waiting times can also be extensive, varying across species. Time to positive blood cultures can range from 19–22 hours for Candida tropicalis to 60–75 hours for Candida glabrata.^1,2
 

With a potential invasive fungal infection (IFI), there is no time to wait. Late initiation of

antifungal therapy significantly increases mortality in invasive candidiasis.^1,2

TOOLS FOR TESTING
 

New strategies are emerging that can shorten diagnostic time for invasive candidiasis:^1,2

• Yeast Traffic Light PNA FISH^TM is a next-generation, three-probe Peptid Nucleic Acid Fluorescence In-Situ Hybridization (PNA-FISH) system, which can identify Candida albicans/Candida parapsilosis, Candida glabrata/Candida krusei and Candida tropicalis performed from blood cultures in 90 minutes.
• MALDI-TOF technology identifies yeasts directly from positive blood culture bottles in 30 minutes, without the need for a subculture. It has sensitivity for Candida albicans and non-Candida albicans species (95.9% and 86.5%, respectively), but sample preparation does require time and a high level of expertise.
• Multiplex-PCR platforms detects many pathogens, including five Candida species, with good specificity and sensitivity for yeast. Taking only 5 minutes to set up, it can provide results in one hour. But only one sample runs at a time, which can cause delays.

The above techniques all rely on a positive blood culture. A new approach using magnetic resonance can be performed on whole blood. This method lyses Candida cells, amplifies DNA with pan-Candida primers, and detects the amplified product. It’s fast and simple, with a response time of less than 4 hours and sample preparation of less than 10 minutes. However, the test is costly and the reagents have a short shelf-life.¹

Current methods for diagnosing invasive yeast infections have limitations.^1,2 But we must continue practising the principles of stewardship, making use of existing tools for a timely and accurate diagnosis. Together we can make real progress against antifungal resistance.