Expanding Diagnostic Options for Pediatric Meningitis: BCID2 Testing Results on Cerebrospinal Fluid After a Negative Meningitis/Encephalitis Panel

Background: Rapid etiological diagnosis of bacterial meningitis is crucial in children, as delays can lead to neurological sequelae. The BioFire FilmArray Meningitis/Encephalitis (ME) panel is widely used on cerebrospinal fluid (CSF), but its target spectrum may miss healthcare-associated or multidrug-resistant pathogens. We evaluated the diagnostic performance and stewardship-oriented clinical impact of off-label BioFire FilmArray Blood Culture Identification 2 (BCID2) testing on CSF from pediatric patients with suspected bacterial CNS infection and negative ME results. Methods: We retrospectively analyzed CSF samples collected between January 2023 and March 2025 at a tertiary pediatric hospital. In ME-negative cases with persistent suspicion and abnormal CSF parameters, BCID2 was performed off-label on residual CSF aliquots after routine testing, without additional sampling. We assessed pathogen detection, agreement with culture, resistance-gene identification, and documented stewardship actions. Results: Among 76 ME-negative CSF samples tested with BCID2, 23 (30.3%) were positive, all involving organisms not included in the ME panel. BCID2 was concordant with culture in 19/23 cases (82.6%); 4/23 (17.4%) were BCID2-positive/culture-negative, consistent with reduced culture sensitivity in frequently pretreated cases. Resistance genes (VIM, vanA/B, CTX-M) were detected in 30.4% of BCID2-positive samples. Overall agreement with culture was 94.7% (PPA 100%, NPA 93.0%). Escalation was documented in 13/23 episodes (56.5%), discontinuation in 2/23 (8.7%), and confirmation in 9/23 (39.1%), with no de-escalation events; clinical outcomes were not systematically available. Conclusions: In selected ME-negative pediatric cases with abnormal CSF profiles, BCID2 testing on residual CSF provided rapid, clinically meaningful microbiological information that may support antimicrobial optimization.