TABLE 94.7 EMPIRIC ANTIBIOTIC THERAPY FOR SUSPECTED ACUTE BACTERIAL MENINGITIS Age Most common pathogens Empiric antibiotics 3 months of age) should be initiated Most patients need no further tests, but in atypical situations, consideration should always be given to nonviral causes that may mandate additional diagnostic steps or specific therapy If tuberculosis is suspected based on family contacts, high CSF protein, a low CSF glucose with lymphocytic predominance, or abnormal chest radiography, then a Mantoux tuberculin skin test (TST), and an interferon gamma release assay should be obtained In endemic areas, serologic studies for Lyme disease and antibiotic therapy may be indicated based upon the exposure history and time of year A CT scan provides essential information about patients with symptoms or signs of parameningeal infection, HSV encephalitis, or CNS tumors and hemorrhages Immunosuppressed patients develop infections with a wide variety of unusual bacteria, fungi, and parasites that can be identified in many cases with appropriate examination and culture of the CSF (e.g., India ink and acid-fast stains, cryptococcal antigen testing, fungal and mycobacterial cultures) TABLE 94.9 CAUSES OF ASEPTIC MENINGITIS Viral Enteroviral Herpes simplex virus Arboviral Lymphocytic choriomeningitis virus Mumps Other viral infections Bacterial Early or partially treated bacterial meningitis Parameningeal infection Mycobacterium tuberculosis Borrelia burgdorferi (Lyme disease) Rickettsial diseases Bartonella henselae (cat scratch) Leptospirosis Treponema pallidum (syphilis) Mycoplasma Fungal Cryptococcus Histoplasmosis Parasitic Candida Naegleria Toxoplasmosis Taenia solium (neurocysticercosis) Malaria Trichinosis Noninfectious Neoplasia Kawasaki disease Hemorrhage Collage vascular diseases Hypersensitivity reactions Heavy metal poisoning Sarcoidosis Because the CSF findings in aseptic meningitis overlap those in bacterial infections, hospital admission is usually warranted until the CSF culture results are available However, the experienced clinician may choose to follow the older child as an outpatient if the family is reliable and nonviral causes (e.g., Lyme disease, tuberculosis, cryptococcosis) are clinically unlikely To guide clinicians, the Bacterial Meningitis Score has been derived and validated to identify children at very low risk (negative predictive value 99.7%) for bacterial meningitis Low-risk features are negative CSF Gram stain; CSF absolute neutrophil count (ANC)