Morphology: Gram-negative diplococci (kidney-bean), oxidase-positive, encapsulated.
GramNegOther
Typical drugs
- #1Ceftriaxone— Empiric and directed treatment.
- #2Penicillin G— If PCN-susceptible (most US strains).
Empiric therapy when resistant
Ceftriaxone remains uniformly active. PCN-resistance reported but rare in US — continue empiric ceftriaxone until susceptibilities back.
Resistance mechanisms
Target alteration
Altered PBP2 (rare)
Example: Decreased PCN susceptibility (still typically ceftriaxone-S).
Resistance notes
PCN susceptibility variable globally; ceftriaxone preferred for empiric meningitis.
Common syndromes
Pearls
Adolescents, young adults (college dorms, military), asplenic patients, complement deficiency. Petechial / purpuric rash + fever + meningismus = classic. Chemoprophylaxis for close contacts: ceftriaxone 250 mg IM × 1, ciprofloxacin 500 mg PO × 1, or rifampin 600 mg PO BID × 2 days.
References
- IDSA Bacterial Meningitis (2004)