Table 2.

Etiologies in 614 Patients With Community-Acquired Meningitis

Etiology	CT Indicated (n = 207)	CT Not Indicated (n = 407)	P Valuea
Unknown	85 (41.0)	321 (78.9)	<.001
Urgent treatableb	100 (48.3)	22 (5.4)	<.001
Untreatablec	17 (8.2)	25 (6.1)	.35
Nonurgent treatabled	5 (2.4)	38 (9.5)	.01

Data are presented as No. (%) unless otherwise indicated.

Abbreviation: CT, computed tomography.

^a P values comparing patients with an indication for CT before lumbar puncture vs those who lack indications.

^bIncluding bacterial meningitis (n = 46), Cryptococcus neoformans (n = 51), herpes simplex virus encephalitis (n = 9), Mycobacterium tuberculosis (n = 3), varicella zoster virus (n = 3), central nervous system lymphoma (n = 1), systemic lupus erythematosus flare (n = 1), Toxoplasma gondii (n = 1), infective endocarditis (n = 1), histoplasmosis (n = 1), cerebral aneurysm (n = 1), epidural empyema (n = 1), Brucella (n = 1), and Escherichia coli urinary tract infection (n = 2).

^cIncluding West Nile virus (n = 28), enterovirus (n = 12), St Louis encephalitis virus (n = 1), Epstein-Barr virus (n = 1).

^dIncluding herpes simplex virus meningitis (n = 37), acute human immunodeficiency virus (n = 1), neurosyphilis (n = 1), multiple sclerosis (n = 1), influenza A virus (n = 1), and cytomegalovirus (n = 2).