T2Bacteria magnetic resonance assay for the rapid detection of ESKAPEc pathogens directly in whole blood

Objectives: To evaluate the magnetic resonance-based T2Bacteria Panel assay for direct detection of ESKAPEc (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) pathogens in blood samples of patients with suspected bloodstream infection (BSI). Patients and methods: Adult patients admitted to the Emergency Medicine Department, Infectious Diseases Unit and ICU of a large tertiary-care hospital were included if they had a blood culture (BC) ordered concomitantly with a whole-blood sample for T2Bacteria testing. Results were compared with those of BC and other clinically relevant information. Results: A total of 140 samples from 129 BSI patients were studied. Single bacteria were detected in 15.7% (22/140) and 12.1% (17/140), and multiple bacteria in 2.9% (4/140) and 1.4% (2/140), of samples tested by T2Bacteria and BC, respectively. With respect to the six target (ESKAPEc) species, overall sensitivity and specificity of T2Bacteria across all detection channels in comparison with BC were 83.3% and 97.6%, respectively; these values increased to 89.5% and 98.4%, respectively, when a true-infection criterion (i.e. the same microorganism detected only by T2Bacteria was cultured from another sample type reflecting the source of infection) was used as the comparator. There were 808 T2Bacteria detection results across 112 samples, with concordant negative results, yielding a negative predictive value of 99.8%. The mean time to negative result was 6.1+1.5 h, whereas the mean time to detection/species identification was 5.5+1.4 h. Conclusions: The T2Bacteria Panel assay has the potential to provide accurate and timely diagnosis of ESKAPEc bacteraemia, which might support the direct therapeutic management of BSI patients.