Differentiating bacterial from aseptic meningitis in children is critical for optimal treatment. While symptoms overlap, bacterial meningitis demands immediate antibiotics. Traditionally, CSF culture has been the gold standard for diagnosis, but its yield has declined with widespread vaccination. Consequently, some children with negative cultures may still have bacterial meningitis. The Bacterial Meningitis Score (BMS), a validated clinical prediction rule, offers a valuable tool, particularly in resource-limited settings, to better identify high-risk children and guide more effective treatment strategies.

To evaluate the clinical utility and diagnostic accuracy of the BMS in identifying pediatric patients at high risk for bacterial meningitis.

This retrospective cross-sectional study included 75 pediatric patients (aged 29 days to 18 years) with suspected meningitis seen at the Emergency Room of the Pediatrics Department in Mariano Marcos Memorial Hospital and Medical Center from March to November 2023. Eligible patients underwent lumbar puncture for CSF analysis. The BMS, a five-variable clinical tool including CSF Gram stain, CSF absolute neutrophil count, CSF protein, peripheral absolute neutrophil count, and seizure, were used to classify patients as very low risk (BMS=0) or not very low risk (BMS ≥1).

The diagnostic performance of the Bacterial Meningitis Score (BMS) across different cut-off thresholds is as follows: At a cutoff of ≥1, sensitivity is 100%, specificity is 36.80%, positive predictive value (PPV) is 33.3% (95% CI: 22% – 46%), negative predictive value (NPV) is 100% (95% CI: 84.5% – 100%), positive likelihood ratio (LR+) is 1.58 (95% CI: 1.29 – 1.93), negative likelihood ratio (LR–) is 0 (95% CI: 0 – NaN), and Youden’s index is 0.36. For a cut-off of ≥2, sensitivity is 88.90%, specificity is 78.90%, PPV is 57% (95% CI: 39% – 73%), NPV is 95% (95% CI: 85% – 98%), LR+ is 4.21 (95% CI: 2.48 – 7.16), LR– is 0.14 (95% CI: 0.03 – 0.52), and Youden’s index is 0.67. At a cut-off of ≥3, sensitivity drops to 61.10%, specificity increases to 98.20%, PPV rises to 91% (95% CI: 64% – 98%), NPV is 88%(95% CI: 78% – 94%), LR+ is 33.94 (95% CI: 4.82 – 251.61), LR– is 0.39 (95% CI: 0.22 – 0.70), and Youden’s index is 0.59. Finally, at a cut-off of ≥4, sensitivity is markedly low at 5.56%, specificity is perfect at 100%, PPV is 100% (95% CI: 20% – 100%), NPV is 77% (95% CI: 66% – 85%), LR+ is not applicable, LR– is 0.94 (95% CI: 0.84 – 1.05), and Youden’s index is 0.056. The optimal cutoff based on Youden’s index (0.67) was BMS ≥2, providing a more balanced trade-off between sensitivity (88.90%) and specificity (78.90%).

The BMS is a highly sensitive initial screen for bacterial meningitis in children, but its low specificity at the ≥1 cutoff necessitates a more judicious approach. Employing a ≥2 cutoff (Youden index 0.67) significantly improves diagnostic accuracy, optimizing resource utilization and enabling targeted interventions. While definitive diagnosis requires confirmatory testing, the BMS strategically guides initial triage, particularly crucial in resource-constrained environments.