Meningitis Basics

Meningitis Basics 


Risk Factors: otitis media, sinusitis, immunosuppression, splenectomy, alcoholism, PNA, DM, CSF leak, endocarditis, neurosurgical procedures, penetrating head trauma, indwelling neurosurgical device, advanced age, malignancy, liver disease, unvaccinated to encapsulated organisms 


Most Common Causative Bacteria by age: 

  • Neonates: Group B Streptococcus, S. pneumococcus, E. coli, L. monocytogenes 

  • Infants and Children: S. pneumococcus, H. influenza type B, N. meningitidis 

  • Adolescents/young adults: S. pneumococcus, N. meningitidis 

  • Older Adults: S. pneumococcus, N. meningitidis, L. monocytogenes 


Other causes: Viral (MCC enteroviruses; HSV), fungal (Crytococcus neoformans, Coccidioides immitis, Aspergillus, Candida, Mucormycosis) 



Presentation: Headache (most common symptom), fever, stiff neck, altered mental status; seizures or focal neurologic deficits 


Physical Exam Findings: 

  • Nuchal rigidity  

  • Kernig’s sign - passive neck flexion elicits flexion of hips and knees  

  • Brudzinski sign - passive knee extension with flexed hip elicits contraction of hamstrings  

  • Splinter hemorrhages, petechiae, pustules  



  • Lumbar puncture  

  • Do not perform if thrombocytopenia (platelet count <20-50k), coagulopathy (INR >1.5), or if patient anti-coagulated  

  • CSF studies - gram stain, culture, cell count w/ differential, glucose, protein  

  • Add additional testing if considering fungus, tuberculosis, Borrelia, etc.   

  • ***CT head should be ordered prior to LP if any of the following risk factors are present: 

  • Altered or deteriorating mental status  

  • Focal neurologic deficit  

  • New onset seizure  

  • Papilledema  

  • Immunocompromised state  

  • Malignancy  

  • History of focal CNS disease (stroke, focal infection, tumor)  

  • Concern for CNS mass lesion  

  • Age >60 years  

  • CBC, BMP, PT-INR, Blood cultures  



  • Immediate empiric antibiotics +/- antivirals (do not delay for LP)  

  • Neonate: Ampicillin + Gentamicin or Cefotaxime  

  • Infants and Children: 3rd generation cephalosporin (ceftriaxone or cefotaxime) + vancomycin  

  • Adults ages 18-49: 3rd generation cephalosporin (ceftriaxone or cefotaxime) + vancomycin  

  • Adults ages 50+: add ampicillin to above  

  • ***Add acyclovir if suspicious of HSV encephalitis 

  • Steroids - 10mg IV dexamethasone to be administered if strong suspicion for S. pneumococcus as causative agent, only if it can be given before or with first dose of antibiotics    

  • Admit all patients with suspected bacterial meningitis  

  • Droplet isolation  



  • Recommended if exposed to patient w/ N. meningitidis or H. influenzae meningitis (droplet transmission)  

  • High risk exposure - household contacts, exposure to oral secretions (ex. Sharing cups or utensils), intubation of patient without use of a facemask  

  • Ciprofloxacin 500mg PO x1, Ceftriaxone 250mg IM x1, or Rifampin 10mg/kg (max 600mg) every 12 hours x4 doses  





1. Bacterial Meningitis. (2019, August 6). Centers for Disease Control and Prevention. Retrieved October 22, 2020, from 


2. Tanski, ME and Ma, OJ. “Central Nervous System and Spinal Infections.” Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8th Ed. Judith E. Tintinalli, et al. New York, NY: McGraw-Hill, 2016.