Rapid Detection of Candidemia with T2MR

Mortality from candidemia increases with delay in initiating appropriate antifungal therapy. Current diagnostic methods are either time-consuming or nonspecific. However, an assay that uses T2 magnetic resonance (T2MR) has been shown to have high sensitivity and specificity, with results in <3 hours. This technology has been used to develop an automated platform, allowing detection of five Candida species from a single blood specimen without culture or sample preparation. Now, results from a manufacturer-supported study — the first extensive clinical trial of this technology — have been reported.

Participants were inpatients aged 18 to 95 with a blood culture ordered at any of 12 centers between July 2013 and April 2014. Among the 2046 patients who completed the study, 245 (12%) were excluded because of indeterminate T2MR results; in addition, 300 had contrived samples — 250 spiked with various Candida species and 50 Candida-negative controls. The remaining 1501 patients were prospectively followed.

The mean time to a negative result among those prospectively followed was 4.2±0.9 hours for T2MR versus ≥120 hours for standard blood culture. For the four patients with T2MR and blood culture positivity for the same species, the mean time to species identification was 4.4±1.0 hours for T2MR versus 129.9±26.3 hours for standard blood culture (P<0.001). Among the 31 discordant cases, 29 were T2MR-positive and blood culture–negative. Analysis of the spiked specimens revealed an overall sensitivity of 91%, an overall specificity of 99%, and a limit of detection of one to three colony-forming units per mL, depending on the species.