TABLE 3.

Etiologies and Adverse Clinical Outcomes (ACO) in 619 Patients with Community-Acquired Meningitis^a

Etiologyb	< 65 (n = 565)		≥ 65 (n = 54)
	No. (%) of patients	No. (%) of ACOs	No. (%) of patients	No. (%) of ACOs
Unknown*†	385 (68.1)	12 (3.1)	22 (40.7)	8 (36.4)
Urgent treatable*†	104 (18.4)	23 (22.1)	23 (42.6)	13 (56.5)
Bacterial meningitis*c	30	7	16	8
Cryptococcus neoformans	44	5	0	0
Herpes simplex encephalitis	11	6	2	2
Mycobacterium tuberculosis	5	2	0	0
Varicella zoster virus	5	0	2	2
CNS lymphoma/carcinomatosis	2	2	1	1
Otherd	7	1	2	0
Untreatable*†	35 (6.2)	7 (20.0)	9 (16.7)	7 (77.8)
West Nile Virus	20	7	9	7
Enterovirus	11	0	0	0
St Louis encephalitis virus	3	0	0	0
Epstein-Barr virus	1	0	0	0
Non-urgent treatable*	41 (7.3)	0 (0)	0 (0)	0 (0)
Herpes simplex meningitis	34	0	0	0
Acute HIV	3	0	0	0
Othere	4	0	0	0
Total	565 (100.0)	42 (7.4)	54 (100.0)	28 (51.9)

^aCNS = central nervous system; HIV = human immunodeficiency virus

^bSignificant p values (p < 0.05) comparing the etiologies (*) and ACOs (^†) between <65 and ≥65 cohorts.

^cOrganisms identified are expressed as a ratio of (<65) to (≥65) and include Streptococcus pneumoniae (11:17), Enterobacter cloacae (1:0), Enterococcus (1:1), Haemophilus influenzae (1:1), Listeria monocytogenes (1:0), Methicillin-sensitive Staphylococcus aureus (1:0), Neisseria meningitidis (2:0), Staphylococcus aureus (1:1), Coagulase-negative Staphylococcus (1:0), Group A Streptococcus (2:0), Group B Streptococcus (0:3), Streptococcus anginosusmilleri (1:0).

^dOther urgent treatable etiologies include Systemic lupus erythematosus flare, Toxoplasma gondii, infective endocarditis, histoplasmosis, cerebral aneurysm, epidural empyema, Brucella, and Escherichia coli urinary tract infection.

^eOther nonurgent treatable etiologies include neurosyphilis, multiple sclerosis, influenza virus type A, and cytomegalovirus.