Acute Bacterial Meningitis
causes::
Neonates  -- Group B strep > E. Coli > Listeria monocytogenes
Children>3m -- Neisseria meningitidis > Strep Pneumo > Listeria
Adults (18-50) -- S. Pneumo > Neisseria > Haemophilus Influenza
Elderly (>50) --  S. Pneumo > Neisseria > Listeria
tx: ceftriaxone or cefotaxime+vancomycin+ampicillin
Immunocompromised -- Listeria > gram-neg bacilli > S. pneumo
tx:  ceftazidime+ampicillin+vancomycin

CSF::
Aseptic -- mostly lymphocytes and monocytes, WBC <1,000, normal glucose.
Bacterial -- mostly PMNs. high WBC (>1,000), Low glucose.

Clinical:
symptoms:  headache, fever, stiff neck, n/v, photophobia, Altered mental status.
signs:  stiff nech, Rashes (neisseria-> purpura), vesicular lesions (HSV, Varicella), increase in ICP (causes papilledema, seizures), CN palsies,
Kernig's sign-- cant extend knees when lying down with hips flexed 90 degrees
Brudzinski's sign-- passive flexion of the neck causes flexion of the legs and thighs.