Repeat Meningitis/Encephalitis Syndromic Panel Testing After an Index-Negative Result: A Retrospective Laboratory-Record Study
TL;DR
These findings provide laboratory context for repeat testing but do not determine patient-level clinical appropriateness or exclude central nervous system infection.
Abstract
Syndromic molecular panels rapidly detect predefined central nervous system pathogens, but the incremental microbiological yield of repeating the same panel after an index-negative result is uncertain. We retrospectively analyzed 313 meningitis/encephalitis (ME)-panel episodes from 265 patients from September 2023 to March 2026. Among 228 patients with a first-observed index-negative panel, 30 underwent subsequent repeat testing and 198 had no subsequent repeat ME-panel test recorded at this institution during the study period. Repeat-tested patients had higher index-panel-linked cerebrospinal fluid (CSF) white blood cell (WBC) counts (median 28.0 vs. 4.0 cells/µL; p < 0.001) and protein concentrations (73.4 vs. 52.4 mg/dL; p = 0.004), whereas glucose did not differ significantly. In the 30 repeat-tested index-negative patients, no negative-to-positive conversion was observed (0/30; exact 95% confidence interval, 0.0–11.6%), and none of the 44 repeat tests detected a new on-panel target. Among 28 persistently negative patients with paired CSF WBC results, the median count decreased from 30.5 to 3.5 cells/µL. Clinical indications, treatment exposure, immune status, and final diagnoses were unavailable. These findings provide laboratory context for repeat testing but do not determine patient-level clinical appropriateness or exclude central nervous system infection.