Snapshot A 19-year-old man presents to the emergency department with a headache. His headache was initially mild but then subsequently worsened over the course 2 days. His headaches are associated with fevers, chills, photophobia, and neck stiffness. His temperature is 101°F (38.3°C), blood pressure is 124/95 mmHg, pulse is 118/min, and respirations are 22/min. Physical examination is notable for nuchal rigidity and petechieal hemorrhages in the skin. An emergent lumbar puncture is performed and blood cultures are obtained. Immediately after, he is started on intravenous vancomycin and ceftriaxone. (Meningococcal meningitis) Introduction Definition inflammation of the meninges that can be caused by infection (bacterial, viral, and fungal) autoimmune disease malignancy medications Etiology infection bacterial viral fungal autoimmune disease neurosarcoid Behcet syndrome malignancy leptomeningeal carcinomatosis hemotologic malignancy medications trimethoprim-sulfamethoxazole non-steroidal anti-inflammatory drugs intravenous immunoglobulins inflixamab Epidemiology incidence aseptic meningitis is more common than bacterial meningitis enteroviruses are the most common cause of viral meningitis Prognosis bacterial meningitis is a medical emergency requiring prompt antibiotic treatment Presentation Symptoms headache confusion photophobia Physical exam nuchal rigidity positive Kernig sign patient supine knee extension while hips are 90° flexed → resistance/pain positive Brudzinski sign patient supine passive neck flexion → involuntary knee flexion petechial rash may suggest Neisseria meningitidis infection Studies Lumbar puncture helps suggest which type of meningitis the patient has studies must include opening pressure cell count protein glucose Gram stain culture other tests depend on the clinical scenario e.g., acid fast bacillus (AFB) stain in patients who are likely to have tuberculosis Serum studies blood cultures especially helpful in patients who urgently require antibiotics but are unable to get a lumbar puncture immediately Cerebrospinal Fluid Analysis Test Normal Bacterial Viral Fungal/TB Opening pressure ≤ 20 cm H 2O ↑ Normal or slightly ↑ ↑ Color Clear Cloudy Clear Cloudy Cell count 0-5 cells/µL ↑ PMN ↑ (Lymphocytes) ↑ (Lymphocytes) Protein < 45 mg/dL ↑ Slighty ↑ ↑ CSF:Serum glucose > 0.6 ↓ Normal ↓ Treatment Bacterial Population Causative Organism Treatment Infants (<1 month) Streptococcus agalactiae (group B streptococcus) Listeria monocytogenes Escherichia coli other gram-negative bacilli Ampicillin and cefotaxime 1-23 months of age Streptococcus pneumoniae Neisseria meningitidis S. agalactiae Haemophilus influenzae E. coli Vancomycin and ceftriaxone In cases of streptococcal pneumoniae, patients can benefit from dexamethasone 2-50 years of age N. meningitidis S. pneumoniae Vancomycin and ceftriaxone > 50 years of age of immunocompromised S. pneumoniae Listeria monocytogenes N. meningitidis aerobic gram-negative bacilli Vancomycin, ceftriaxone, and ampicillin Viral meningitis supportive treatment Meningococcal prophylaxis indication roomates or intimate contacts child care center workers direct exposure (e.g., kissing and endotracheal intubation) sitting next to the affected person for ≥ 8 hours medication rifampin interacts with oral contraceptives and other medications that use the cytochrome P450 system ceftriaxone ciprofloxacin Cryptococcal meningitis treatment amphotericin with flucytosine followed by fluconazole Complications Neurological sequela (e.g., cognitive deficit) Septic sinus thrombosis Subudural effusion or empyema