A nanodiagnostic panel was able to identify the fungus Candida in whole blood within several hours, a much quicker turnaround than standard blood or fungal culture methods. Results were published in Clinical Infectious Diseases.
Blood culture is considered the gold standard for detecting Candida, but positive results may take several days to appear, and the test suffers from poor sensitivity. At least 50% of the time, cultures fail to identify Candida infections. Due to these shortfalls in testing, patients with candidemia often have poor outcomes, and some die as a result of not receiving antifungal therapy in a timely manner.
Fungal culture can take even longer than blood culture—up to several weeks, study co-author Alan Wu, PhD, director of clinical chemistry and toxicology at the University of California at San Francisco, told CLN Stat. An alternative to blood culture is the T2Candida panel, which leverages magnetic resonance and polymerase chain reaction (PCR) technologies to scan blood samples for common Candida species. Results are available in 4 to 5 hours. “The fact that you can get earlier results is a game-changer for sure,” said Wu. A swift diagnosis that pinpoints a specific infection means the patient gets the appropriate medication for his or her diagnosis, instead of broad spectrum antibiotics that may or may not be effective and could lead to drug resistance, he elaborated. According to Wu, T2Candida’s use of magnetic resonance is what makes this particular test unique from other types of molecular microbiologic detection panels.
Investigators through a prospective, multicenter trial known as DIRECT2 tested T2Candida’s effectiveness to identify candidemia in 152 hospitalized patients previously diagnosed at 14 U.S.-based centers with the infection via a blood culture. Test subjects provided resamples for both blood culture and the T2Candida test, the latter of which yielded an 89% clinical sensitivity. For those with recent cases of candidemia and not receiving antifungal therapy, T2Candida performance (32.5% positive) was very close to companion blood culture tests (30% positive). In some cases when patients received antifungal therapy, the test was able to identify Candida infection that blood cultures failed to detect.
“Our trial demonstrates that the T2Candida panel is an important advance in the diagnosis of candidemia,” said lead author Cornelius J. Clancy, MD, associate professor of medicine at the University of Pittsburgh, in a statement.
While the T2Candida system shows promise for rapidly and accurately diagnosing patients and reducing high death rates due to candidemia, “these better outcomes remain unproven,” observed H. Bradford Hawley, MD of the Division of Infectious Diseases at Wright State University’s Boonshoft School of Medicine, in a related editorial.
The test’s cost effectiveness “will depend upon the incidence of candidemia in individual hospitals as well as high-risk groups of patients in those hospitals,” wrote Hawley. “Additionally, hospitals must have a reporting system and medical staff that can respond to rapid test results without delay by initiating appropriate therapy.”
A future clinical trial should be conducted in real time, evaluating T2Candida’s use in other forms of Candida and the impact of results with antibiotic use, Wu suggested.