Table 3.
Atiologies of 323 patients with meningitis and a negative cerebrospinal fluid Gram stain
| Aetiology | Method of detection | New Orleans cohort (N = 205) n/N (%) |
Houston cohort (N = 118) n/N (%) |
All cohorts (N = 323) n/N (%) |
P value |
|---|---|---|---|---|---|
| Unknown | 148/205 (72·1%) | 63/118 (53·4%) | 211/323 (65·3%) | <0·01 | |
| Confirmed aetiology | 42/205 (20·5%) | 47/118 (39·8%) | 89/323 (27·5%) | <0·01 | |
| Viral | 17/205 (8·3%) | 31/118 (26·3%) | 48/323 (14·9%) | <0·01 | |
| Enterovirus | By PCR on CSF By viral culture |
7 1 |
6 0 |
13 1 |
|
| Herpes simplex 1 and 2 | PCR on CSF | 4 | 8 | 12 | |
| Varicella zoster virus | PCR on CSF | 3 | 3 | 6 | |
| St Louis encephalitis | Serology on CSF or serum | 1 | 6 | 7 | |
| West Nile virus | Serology on CSF or serum | 1 | 7 | 8 | |
| Acute HIV | PCR on serum with negative serology | 0 | 1 | 1 | |
| Bacterial | 12/205 (5·8%) | 10/118 (8·5%) | 22/323 (6·8%) | 0·36 | |
| Streptococcus pneumoniae | CSF cultures, blood cultures and BinaxNow | 3 | 4 | 7 | |
| Staphylococcus aureus | CSF cultures and blood cultures | 5 | 2 | 7 | |
| Group b streptococcus | CSF cultures and blood cultures | 1 | 3 | 4 | |
| Listeria monocytogenes | CSF culture | 1 | 0 | 1 | |
| Escherichia coli | blood cultures | 2 | 1 | 3 | |
| Other | 13/205 (6·3%) | 6/118 (5·1%) | 19/323 (5·9%) | 0·8 | |
| Cryptococcus neoformans | Cryptococcal antigen on CSF/serum or growth CSF culture | 8 | 2 | 10 | |
| Treponema pallidum | VDRL on CSF | 1 | 2 | 3 | |
| Mycobacterium tuberculosis | By CSF cultures or respiratory cultures | 2 | 1 | 3 | |
| CNS bleed | Imaging | 2 | 0 | 2 | |
| Histoplasma capsulatum | CSF Fungal cultures | 0 | 1 | 1 | |
| Presumed aetiology | 15/205 (7·3%) | 8/118 (6·8%) | 23/323 (7·1%) | 0·99 | |
| Mycoplasma pneumonia | Serology (+IgM and −IgG) | 2 | 2 | 4 | |
| Rocky mountain spotted fever | Serology (+IgM and −IgG) | 3 | 1 | 4 | |
| Cytomegalovirus | Serology (+IgM and −IgG) | 3 | 1 | 4 | |
| Epstein–Barr virus | Serology (+IgM and −IgG) | 1 | 2 | 3 | |
| Lymphocytic choriomeningitis virus | Serology | 2 | 1 | 3 | |
| Bartonella henselae | Serology | 1 | 1 | 2 | |
| Toxoplasma gondii | Positive serology with radiological findings in AIDS patient | 1 | 0 | 1 | |
| Ehrlichia chaffeensis | By IFA on serum | 1 | 0 | 1 | |
| CNS vasculitis | Imaging | 1 | 0 | 1 |
PCR, Polymerase chain reaction; CSF, cerebrospinal fluid; VDRL, Venereal Disease Research Laboratory; CNS, central nervous system; HIV, human immunodeficiency virus; AIDS, acquired immune deficiency syndrome; IFA, indirect fluorescent antibody.
Comparing the New Orleans cohort and Houston cohort using Fisher's exact test.