Innovative Blood Test Rapidly Detects Candidemia

Candidemia is among the four most common bloodstream infections in hospitals in the USA, and Candida are the third most common cause of infections in intensive care units. The mortality rate among patients with candidemia is 40%.

Blood cultures fail to detect yeast in approximately 50% of Candida infections, and typically take two to three days for positive results to be apparent. A commercial blood test seems to perform as well as, if not better than, traditional blood cultures at detecting a type of fungal yeast infection that commonly strikes hospital patients.

Scientists at the University of Pittsburgh Medical Center (Pittsburgh, PA, USA) and their colleagues enrolled from 14 health centers 152 patients who had been diagnosed with candidemia through a blood culture. On average, it took nearly two days for the culture to identify that the patient had candidemia, and another day-and-a-half to specify which strain of Candida. Patients with Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, or Candida krusei candidemia were identified at the 14 centers using diagnostic blood cultures (dBCs). Follow-up blood samples were collected concurrently for testing by T2Candida panel (T2 Biosystems, Lexington, MA, USA) and companion cultures (cBCs).

T2Candida results were reported qualitatively for C. albicans/C. tropicalis, C. glabrata/C. krusei, and C. parapsilosis. T2Candida and cBCs were positive if they detected a species present in the dBC. Median time between collection of dBC and T2Candida/cBC samples in 152 patients was 55.5 hours (range, 16.4–148.4). T2Candida and cBCs were positive in 45% (69/152) and 24% (36/152) of patients, respectively. T2Candida clinical sensitivity was 89%, as positive results were obtained in 32/36 patients with positive cBCs. Prior antifungal therapy, neutropenia, and C. albicans candidemia were independently associated with T2Candida positivity.

The authors concluded that T2Candida was sensitive for diagnosing candidemia at the time of positive blood cultures. In patients receiving antifungal therapy, T2Candida identified bloodstream infections that were missed by cBCs. T2Candida may improve care by shortening times to Candida detection and species identification compared to blood cultures, retaining sensitivity during antifungal therapy and rendering active candidemia unlikely if results are negative. The study was published on February 9, 2018, in the journal Clinical Infectious Diseases.

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University of Pittsburgh Medical Center
T2 Biosystems