Clinical impact of a rapid multiplex PCR assay on the diagnosis and management of viral infections after HSCT.

Hematopoietic stem cell transplantation (HSCT) recipients are highly susceptible to viral infections, many of which are missed by conventional diagnostic tests owing to limited coverage and slow turnaround times. This single-center, prospective observational study evaluated a rapid multiplex PCR (mPCR) assay to detect 13 DNA viruses for diagnosis and management of post-HSCT viral infections. Between December 2020 and March 2025, 63 HSCT recipients with suspected viral infections underwent mPCR testing of blood (n = 51) or cerebrospinal fluid (CSF) (n = 12) in parallel with standard diagnostics. The mPCR results were reported within 24 h and integrated into clinical decision-making. The etiology was identified in 44 of 51 (86%) blood samples (30 infections) and 9 of 12 (75%) CSF samples (5 infections). mPCR provided the sole etiological diagnosis in 19 of 63 (30%) episodes: 15 of 51 (29%) blood and 4 of 12 (33%) CSF samples. mPCR enabled targeted treatment in 15 of 63 (24%) episodes: 11 of 51 (22%) blood and 4 of 12 (33%) CSF samples. Unexpected infections, such as varicella-zoster virus meningitis and human herpesvirus 7 encephalitis, were identified only by mPCR. Rapid mPCR provided timely, actionable diagnosis and directly influenced the clinical management of post-HSCT patients.