Rapid molecular detection of bacteremia in children: clinical utility and limitations of the t2bacteria panel a single-center retrospective analysis

Bloodstream infections and sepsis represent a leading cause of morbidity and mortality in pediatric patients. Conventional blood culture, while considered the diagnostic gold standard, is limited by turnaround times of up to 72 h. T2 Magnetic Resonance (T2MR) technology enables rapid, culture-independent detection of bacterial pathogens directly from whole blood within 3–5 h. This study evaluated the diagnostic performance of the T2Bacteria panel in hospitalized children with suspected bloodstream infection and compared it with conventional blood culture. This retrospective study included 51 pediatric patients (aged 6 days to 17 years) hospitalized at the University Children’s Hospital in Kraków between November 2023 and February 2025. A total of 62 paired blood samples were analyzed using both methods. Clinical parameters including C-reactive protein (CRP), procalcitonin, and white blood cell count were recorded. Agreement between methods was assessed using Cohen’s kappa, and the sensitivity, specificity, and predictive values of T2Bacteria were calculated using blood culture as the reference standard. Clinical parameters were compared across mutually exclusive result groups using nonparametric tests with correction for multiple comparisons. Bacteria were identified in 11/62 blood cultures (17.7%) and 16/62 T2Bacteria tests (25.8%). Overall agreement between methods was 82.3% (51/62; κ = 0.48, 95% CI 0.21–0.76). Both methods were positive in 8 samples (identical species in 5, different species in 3), 8 samples were positive by T2Bacteria only, and 3 by blood culture only. Using blood culture as the reference, T2Bacteria sensitivity was 72.7% (8/11) and specificity 84.3% (43/51). Median time to pathogen identification was 22.5 h by blood culture (data available for 3 samples) versus 4.1 h by T2Bacteria. T2Bacteria provided faster pathogen detection and identified organisms in a subset of culture-negative samples, although these results could not be confirmed in other clinical specimens. However, its utility was limited by a narrow pathogen panel, inability to detect coagulase-negative staphylococci, and blood volume requirements that are challenging in neonates. As the T2Dx platform is no longer commercially available, these findings are best interpreted as evidence on rapid, culture-independent pathogen detection directly from whole blood, which should complement rather than replace blood culture in pediatric diagnostic algorithms.