Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
    • Suggested protocolsAlgorithm





    Chief Complaint


    Organ System


    Patent Pending

    Bacterial Meningitis Score for Children

    Determines likelihood of aseptic or bacterial meningitis.


    Use in patients aged 29 days to 19 years with CSF WBC ≥10 cells/μL. Do not use if patient is critically ill, recently received antibiotics, has a VP shunt or recent neurosurgery, is immunosuppressed, or has other bacterial infection requiring antibiotics (including Lyme disease).

    When to Use
    Why Use

    Pediatric patients (aged 29 days to 19 years) with suspected meningitis.

    Do NOT use if the patient:

    • Is critically ill, requiring respiratory or vasopressor support.
    • Received antibiotics <72 hours prior to lumbar puncture.
    • Has a VP shunt or recent neurosurgery.
    • Is immunosuppressed.
    • Has proof of another bacterial infection (e.g. UTI, bone infection, known bacteremia) that warrants inpatient antibiotic therapy.
    • Has known active Lyme Disease.
    • The Bacterial Meningitis Score (BMS) predicts bacterial vs. aseptic etiology in pediatric patients (aged 29 days to 19 years) with suspected meningitis.  
    • Can help determine if the patient will require admission for parenteral antibiotics while awaiting CSF culture results.
    • Higher score indicates higher likelihood of bacterial meningitis.
    • Sensitivity, specificity, and negative predictive value of the BMS decrease significantly for children under the age of 2 months.
    • Creators of the BMS advise against using the score in children who have already received antibiotics prior to LP, are ill-appearing, are <2 months of age, or have exam findings indicative of invasive bacterial infection such as petechiae and purpura.
    • Not effective at ruling out potentially harmful nervous system infections requiring antibiotics (e.g. herpes encephalitis, Lyme meningitis, tuberculous meningitis).
    • Meningococcal meningitis can present without CSF pleocytosis; thus, these patients can be misclassified as not having inclusion criteria for the use of the BMS. It is important to perform a thorough physical exam to assess for petechiae or purpura if there is suspicion for meningococcemia or meningitis, as CSF may be falsely normal.
    • Bacterial meningitis incidence has dramatically decreased since the advent of highly effective vaccines against the more common causes (H. flu, S. pneumo), making it more challenging to determine which patients should be admitted and observed while awaiting CSF culture results.
    • Helps stratify which patients do not necessarily require observation, due to higher likelihood of aseptic (i.e., spontaneously resolving) meningitis.
    • Helps avoid financial burden and health risk associated with hospitalization for observation and parenteral antibiotic administration.
    About the Creator
    Dr. Lise Nigrovic
    Content Contributors
    • Cullen Clark, MD


    Please fill out required fields.

    Next Steps
    Creator Insights


    For patients at very low risk for bacterial meningitis (BMS 0):

    • Consider discharge with close follow-up (ideally within 24–48 hours) and return precautions for family, including new seizure activity, altered mental status, purpuric rash, or other concerning symptoms.
    • Patients may have received a dose of empiric antibiotics after LP was performed if concern for bacterial meningitis. If no antibiotics were administered, consider a single dose of long-acting antibiotics with good CSF penetration, such as ceftriaxone, prior to discharge.  

    For patients with at least 1 risk factor for bacterial meningitis or high clinical suspicion (BMS >0):

    • Consider admission for parenteral antibiotics and observation while awaiting CSF culture results.
    • Make sure CSF is sent for culture.
    • Consider continuous monitoring of vital signs and regular neurologic exams.
    • If not previously administered, start empiric broad spectrum antibiotics.
    • Consider expanding antimicrobial coverage:
      • If concern for herpes encephalitis, add acyclovir.
      • If high clinical suspicion for tuberculous meningitis, consult with infectious disease specialist and consider rifampin, isoniazid, pyrazinamide, and a fluoroquinolone or aminoglycoside.
    • Consider steroid administration based on clinical presentation, geographic area, and potential risk factors.

    Critical Actions

    • Physician gestalt, severity of illness and clinical presentation supersedes the application of the BMS prediction rule.
    • If significant suspicion for bacterial meningitis, err on the side of caution and admit for observation and empiric antibiotics.


    Addition of the selected points:



    0 points

    1 point

    CSF Gram stain



    CSF absolute neutrophil count (ANC)

    <1,000 cells/μL

    ≥1,000 cells/µL

    CSF protein

    <80 mg/dL (800 mg/L)

    ≥80 mg/dL (800 mg/L)

    Peripheral blood ANC

    <10,000 cells/μL

    ≥10,000 cells/μL

    Seizure at (or prior to) initial presentation



    Facts & Figures


    Bacterial Meningitis Score

    Risk for Bacterial Meningitis


    Very low risk


    Not very low risk

    Evidence Appraisal

    The original Bacterial Meningitis Score was derived from a multicenter, retrospective cohort study published by Nigrovic et al in JAMA 2007.  Data were collected from 20 participating emergency departments of academic medical centers over a three year period. 3,295 patients aged 29 days to 19 years with CSF pleocytosis were scored using the BMS.

    Of the 1,714 who were categorized as very low risk, two were found to have bacterial meningitis. Both miscategorized patients were <2 months of age and had E. coli meningitis with an E. coli UTI but negative urinalysis.

    Sensitivity of BMS for bacterial meningitis was 98.3% (95% CI 94.2-99.8%). NPV was 99.9% (95% CI 99.6-100%). The investigators attempted to refine the score using recursive partitioning, which led to a simpler model with only three variables, but it also led to one additional patient with meningitis being misclassified as very low risk.

    Given the two misclassified patients were under the age of two months, the investigators analyzed the BMS for a subgroup of all patients under two months of age and found sensitivity was 92.3% (95% CI 74.9-99.4%), NPV 99.5% (95% CI 98.3-99.9%).

    The BMS was validated by Nigrovic et al in Archive of Disease in Childhood, 2012. This was a meta analysis of studies published between 2002 and 2012 and included 4,896 patients aged 29 days to 19 years. Sensitivity was 99.3% (95% CI 98.7-99.7%) for bacterial meningitis and NPV was 98.3% (95% CI 96.6-99.3%).

    Kulik et al in 2013 published a systematic review of several bacterial meningitis predictive rules, and of the studies reviewed, the BMS had the highest quality evidence and the best performance to date. They recommended that the score still be further evaluated with prospective trials.


    Dr. Lise Nigrovic

    About the Creator

    Lise E. Nigrovic, MD, MPH, is an associate professor of pediatrics and emergency medicine at Harvard Medical School. She serves as co-director of Population Science for the Institutional Centers for Clinical and Translational Research (ICCTR) and the Boston Children’s Hospital Medical Research Office for Harvard Catalyst. Dr. Nigrovic’s research focus has been in the approach to diagnosis and management of children with infectious and traumatic emergencies.

    To view Dr. Lise Nigrovic's publications, visit PubMed

    Content Contributors
    • Cullen Clark, MD