| Characteristic | No colonised (%) | OR (95% CI)* | p Value |
| City | 0.86 | ||
| New Orleans | 75 (68) | Referent | |
| San Francisco | 42 (69) | 1.06 (0.54–2.08) | |
| Age (y) | 0.84 | ||
| <35 | 19 (70) | Referent | |
| 35–44 | 49 (65) | 0.79 (0.31–2.06) | |
| 45–54 | 41 (72) | 1.08 (0.39–2.96) | |
| ⩾55 | 5 (63) | 0.70 (0.13–3.66) | |
| Sex | 0.60 | ||
| Female | 34 (71) | Referent | |
| Male | 82 (67) | 0.82 (0.40–1.70) | |
| Ethnicity | 0.42 | ||
| African–American | 81 (66) | Referent | |
| Caucasian | 23 (70) | 1.19 (0.52–2.74) | |
| Other | 13 (81) | 2.25 (0.61–8.32) | |
| CD4+ T cell count (cells/μl) | 0.12 | ||
| >200 | 25 (69) | Referent | |
| 101–200 | 19 (59) | 0.64 (0.24–1.75) | |
| 51–100 | 15 (65) | 0.83 (0.27–2.51) | |
| ⩽50 | 45 (82) | 1.98 (0.74–5.31) | |
| HIV RNA (copies/ml) | 0.24 | ||
| <75 | 7 (78) | Referent | |
| ⩾75 and <20 000 | 11 (55) | 0.35 (0.06–2.12) | |
| ⩾20 000 and <100 000 | 26 (81) | 1.24 (0.20–7.53) | |
| ⩾100 000 | 39 (72) | 0.74 (0.14–3.99) | |
| Prior PCP | 0.16 | ||
| No | 77 (65) | Referent | |
| Yes | 40 (75) | 1.68 (0.81–3.48) | |
| PCP prophylaxis on admit | 0.077 | ||
| No | 72 (73) | Referent | |
| Yes | 43 (61) | 0.55 (0.29–1.07) | |
| PCP prophylaxis category | 0.059 | ||
| None | 72 (73) | Referent | |
| Co-trimoxazole | 28 (55) | 0.44 (0.22–0.89) | |
| Other | 15 (75) | 1.08 (0.36–3.28) | |
| Aetiology of pneumonia | 0.79 | ||
| Bacterial | 72 (69) | Referent | |
| Opportunistic† | 13 (59) | 0.64 (0.25–1.65) | |
| Non-infectious‡ | 12 (67) | 0.89 (0.31–2.58) | |
| Undiagnosed | 20 (71) | 1.11 (0.44–2.79) |
*Up to 57 observations may be missing (as for HIV RNA), but OR are calculated using actual observations only. †Includes mycobacterial, fungal and viral pneumonias. ‡Includes Kaposi’s sarcoma, lymphoma and other non-infectious pulmonary processes, such as chronic obstructive pulmonary disease exacerbations and pulmonary oedema. PCP, Pneumocystis pneumonia.