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      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

    Rules out 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.


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    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.
    • 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.
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    About the Creator
    Dr. Lise Nigrovic
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