A new blood test seems to perform as well as, if not better
than, traditional blood cultures at detecting candidemia that commonly strikes
hospital patients, according to an analysis led by University of Pittsburgh
Schools of the Health Sciences.
The T2Candida Panel is the first diagnostic test
for candidemia that has been cleared by the US Food and Drug
Administration and doesn’t require culturing a blood sample from the
patient to see what grows. The results of the trial, named DIRECT2, are
reported in the journal Clinical
Infectious Diseases. The trial was funded by T2 Biosystems, the
company that makes the panel, which is used by UPMC.
“There are many advantages to quickly diagnosing the
specific type of infection a patient has,” said lead author Cornelius J.
Clancy, MD, associate professor of medicine in the University of
Pittsburgh’s Division of Infectious Diseases, and director of the mycology
program. “With an accurate diagnosis, we can start the patient on the correct
medication for the type of infection he or she has, which will hopefully allow
us to stop the infection before it spreads, but also keep us from giving the
patient a drug that won’t work and potentially contributing to drug resistance.
For candidemia, we know that the shorter the time to administering an active
antifungal medication to a patient, the higher the survival rate. ”
Candidemia is among the four most common bloodstream
infections in US hospitals, 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.
The T2Candida Panel involves putting a small vial of blood
from the patient into a desktop machine that uses magnetic resonance
to scan the blood for the five most common Candida species. Positive or
negative results are available within five hours.
From 14 US hospitals, Clancy’s team enrolled 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.
In the trial, the T2Candida test was positive in 89%
of patients at the time of a positive blood culture for Candida. The T2Candida
Panel was significantly more likely to be positive than blood cultures in
patients with recent candidemia, in particular those patients who were being
treated with antifungal drugs.
While the T2Candida Panel performed well in the trial,
Clancy says there were limitations, including the fact that the study didn’t
assess whether T2Candida shortens time to starting antifungal treatment or
improves patient outcomes.
“Our trial demonstrates that the T2Candida Panel is an
important advance in the diagnosis of candidemia,” said Clancy. “The next steps
should be evaluating it in direct clinical practice and determining if its use
truly speeds up antifungal treatment, cuts unnecessary drug prescribing,
results in better patient outcomes and is cost-effective, and identifies large
numbers of candidemia cases that are currently not detected by blood cultures.”
Reference: Clancy CJ, et al. Detecting Infections Rapidly
and Easily for Candidemia Trial, Part 2 (DIRECT2): A Prospective, Multicenter
Study of the T2Candida Panel. Clinical
Infectious Diseases. Published 9 February 2018.