Bacterial<unk> :
Pneumococcus (60%), meningococcus (15%), group B streptococcus (15%), H flu (7%), listeria (2%)
Viral<unk> 
Echovirus, coxsackies, enterovirus (85%)
HSV, CMV, Herpes B virus
Pneumococcus (60%), meningococcus (15%), group B streptococcus (15%), H flu (7%), listeria (2%)
Echovirus, coxsackies, enterovirus (85%)
HSV, CMV, Herpes B virus
Hematogenous spread via respiratory tract
Contiguous spread (otitis media, sinusitis, brain abscess)
Otitis Media
Sinusitis
Immunosuppression/splenectomy
Alcoholism
Pneumonia
Diabetes Mellitus
CSF leak
Endocarditis
Neurosurgical procedure / head injury
Indwelling neurosurgical device / cochlear implant
Malignancy
Drug induced aseptic<unk> 
NSAIDs
Antimicrobials, see above page for list
NSAIDs
Antimicrobials, see above page for list
Acute (<24hr)
Usually bacterial in origin (25%)
Subacute (1-7d)
Viral or bacterial
Chronic (>7d)
Viral, TB, syphilis, fungi, carcinomatous
Usually bacterial in origin (25%)
Viral or bacterial
Viral, TB, syphilis, fungi, carcinomatous
Meningitis
Migraine headache
Encephalitis
Tension headache
Meningoencephalitis
Cluster headache
Neoplastic meningitis
Meningitis/encephalitis