Diagnostic Impact of FISHseq as a New Pathologic Criterion for Endocarditis According to the Duke Criteria.

Background: For clinicians treating patients with infective endocarditis (IE), identifying the causative microorganisms poses a critical diagnostic challenge. Standard techniques including blood and heart valve cultures often yield inconclusive results. According to the recent 2023 Duke-ISCVID Criteria, molecular methods represent potent tools to enhance this aspect of IE diagnostics and guide subsequent therapeutic strategies.

Methods: We retrospectively analyzed data from 124 consecutive patients who underwent heart valve surgery due to suspected IE at . The standard diagnostic pathway, which included blood culture, valve culture, histopathological analysis, and polymerase chain reaction (PCR)/sequencing, was compared with the enhanced diagnostic pathway, which included fluorescence in situ hybridization + PCR/sequencing (FISHseq) instead of PCR/sequencing alone. The aim of this study was to assess the added value of combining standard diagnostics with molecular methods such as PCR/sequencing or FISHseq for the diagnosis of IE and the potential impact on therapy.

Results: Standard diagnostic methods and PCR/sequencing yielded inconclusive results in 57/124 cases (46.0%). FISHseq provided an added value for diagnostics in 79/124 cases (63.7%) and potentially would have impacted therapy in 95/124 (76.6%) of cases. By adding data through direct visualization and characterization of microorganisms, FISHseq reduced the number of inconclusive cases by 86.0%.

Conclusions: The comparison of 2 molecular diagnostic tools for IE from the same heart valve emphasizes the value of molecular methods including molecular imaging by FISH for IE diagnostics and supports the 2023 Duke-ISCVID Criteria.