Melting temperature mapping for rapid pathogen identification in neonatal bloodstream infections: A prospective study

The melting temperature (Tm) mapping method is a culture-independent diagnostic tool for the early detection of bloodstream infections, utilizing real-time polymerase chain reaction. It identifies 163 bacterial species and quantifies bacterial load within 4 h of sample collection. This study aimed to evaluate its clinical utility in a neonatal intensive care unit (NICU).

This single-center prospective study was conducted at the Toyama University Hospital NICU (2019-2024). Blood samples were collected from neonates diagnosed with or suspected of bloodstream infection for Tm mapping and conventional blood culture (BC). We investigated the rapidity of the Tm mapping method relative to BC and evaluated its clinical utility, including diagnostic accuracy.

Overall, 321 samples were collected from 248 patients, with an average blood volume of 261 μL for Tm mapping. Bacterial species were identified in 26 samples by Tm mapping. Of these, six were BC-positive, and all were identified earlier by Tm mapping. Although some discrepancies in species identification occurred due to polymicrobial infection, the results were consistent with the clinical course. Moreover, three samples yielded BC-negative results but were diagnosed as sepsis based on the Tm mapping results and clinical course. Of the 295 samples without bacterial species identified by Tm mapping, 10 were BC-positive, with four showing true bacteremia and six considered contaminated.

The findings revealed that Tm mapping enabled faster identification of causative bacteria and detected pathogens not identified by BC, suggesting its potential to complement conventional culture-based diagnostics and inform the management of neonatal infections.