Characteristics of monobacterial infections, including a single pyogenic pneumonia(SPP) compared with community-acquired pneumonia cases with a mixed pyogenic pneumonia (MPP) subgroup
| Variable | SPP | MPP | p-value | 95% CI |
| Age >65 yrs | 63 (77) | 16 (57) | 0.04 | 0.14–0.84 |
| Male | 23 (28) | 7 (25) | 1.0 | 0.43–3.07 |
| Previous antimicrobial treatment | 13 (16) | 3 (11) | 0.76 | 0.17–2.42 |
| PSI class I+II | 12 (15) | 4 (14) | 1.0 | 0.29–3.36 |
| PSI class IV+V | 49 (60) | 15 (54) | 0.65 | 0.33–1.91 |
| COPD | 32 (39) | 10 (36) | 0.82 | 0.35–2.05 |
| Any comorbidity | 48 (59) | 22 (79) | 0.17 | 0.69–9.78 |
| Alcoholism | 8 (10) | 6 (21) | 0.18 | 0.12–1.27 |
| Fever prior to admission | 60 (73) | 20 (71) | 0.81 | 0.33–2.24 |
| Expectoration | 65 (79) | 21 (75) | 0.61 | 0.29–2.15 |
| Pleuritic chest pain | 35 (43) | 13 (46) | 0.83 | 0.47–2.62 |
| Crackles | 58 (71) | 22 (79) | 0.62 | 0.49–3.81 |
| Alveolar infiltrates | 61 (74) | 19 (68) | 0.62 | 0.29–1.85 |
| Pleural effusion | 9 (11) | 4 (14) | 0.74 | 0.38–4.79 |
| Interstitial infiltrates | 7 (9) | 3 (11) | 0.71 | 0.31–5.35 |
| Leukocytes >12 or <4x109·µL−1 | 51 (62) | 21 (75) | 0.26 | 0.68–4.69 |
| Mental confusion | 14 (17) | 7 (25) | 0.41 | 0.58–4.54 |
| Systolic blood pressure <90 mmHg | 4 (5) | 5 (18) | 0.05 | 1.07–17.31 |
| Respiratory rate >30·min−1 | 40 (49) | 5 (18) | 0.008 | 0.081–0.67 |
| Creatinine >1.5 mg·dL−1 | 12 (15) | 2 (7) | 0.51 | 0.09–2.17 |
| Temperature <36 or >40°C | 7 (9) | 4 (14) | 0.46 | 0.49–6.71 |
| ICU admission | 7 (9) | 6 (21) | 0.07 | 0.90–9.73 |
| Septic shock | 3 (4) | 5 (18) | 0.03 | 1.27–25.7 |
Data are presented as n (%), unless otherwise stated. CI: confidence interval; PSI: pneumonia severity index; COPD: chronic obstructive pulmonary disease; ICU: intensive care unit.