Effective Rapid Diagnosis of Bacterial and Fungal Bloodstream Infections by T2 Magnetic Resonance Technology in the Pediatric Population

Abstract

Children are prone to bloodstream infections (BSIs), the rapid and accurate diagnosis of which is an unmet clinical need. The T2MR technology is a direct molecular assay for identification of BSI pathogens, which can help to overcome the limits of blood culture (BC) such as diagnostic accuracy, blood volumes required, and turnaround time. We analyzed results obtained with the T2Bacteria (648) and T2Candida (106) panels in pediatric patients of the Bambino Gesù Children's Hospital between May 2018 and September 2020 in order to evaluate the performance of the T2Dx instrument with respect to BC. T2Bacteria and T2Candida panels showed 84.2% and 100% sensitivity with 85.9% and 94.1% specificity, respectively. The sensitivity and specificity of the T2Bacteria panel increased to 94.9% and 98.7%, respectively, when BC was negative but other laboratory data supported the molecular result. T2Bacteria sensitivity was 100% with blood volumes <2 mL in neonates and infants. T2Bacteria and T2Candida provided definitive microorganism identification in a mean time of 4.4 and 3.7 h, respectively, versus 65.7 and 125.5 h for BCs (P < 0.001). T2 panels rapidly and accurately enable a diagnosis of a pediatric BSI, even in children under 1 year of age and for very small blood volumes. These findings support their clinical use in life-threatening pediatric infections, where the time to diagnosis is of utmost importance, in order to improve survival and minimize the long-term sequalae of sepsis. The T2 technology could be further developed to include more bacteria and fungi species that are involved in the etiology of sepsis.

Keywords: T2 magnetic resonance; T2 panels; bloodstream infections; molecular diagnosis; pediatric population.

FIG 1

T2 magnetic resonance results in pediatric patients with suspected bloodstream infections, in comparison with concurrent blood culture. Microorganisms identified by T2Bacteria (Panel a) and T2Candida (Panel b) are shown. ^aTwelve microorganisms identified in 9 patients. ^bInstead of Enterococcus faecium isolated in blood culture. ^cInstead of Klebsiella pneumoniae isolated in blood culture. ^dIsolation of Staphylococcus aureus (n = 2), Enterococcus faecium (n = 1), and Klebsiella pneumoniae (n = 1) in blood cultures.

FIG 2

T2Bacteria panel performance in specific age groups and for different initial blood volume processed. Sensitivity (dots) and specificity (squares) values and 95% confidence intervals for T2Bacteria panel in proven, proven and probable, and proven, probable, and possible BSIs are reported, classified for initial blood volume samples for T2Bacteria panel performance lower (Panel a, orange dots) or higher (Panel b, blue dots) than 2 mL.

FIG 3

Rate of T2Bacteria panel overdetections compared to concurrent blood culture. Rates (and 95% confidence intervals) of samples in which T2Bacteria panel provided additional microorganisms identifications compared to standard blood culture are reported for each age group, classified for initial blood volume samples for T2Bacteria panel performance lower (orange) or higher (blue) than 2 mL.