Treatment and outcome
| Variable | Sporadic cases | Outbreak cases | p-value |
| Subjects n | 138 | 113 | |
| Fine score classes III–V | 48/83 (57.8) | 34/83 (41) | 0.04# |
| Hospital admission | 138 (96.4) | 68 (60) | 0.003# |
| ICU admission | 22 (16.1) | 5 (4.4) | 0.004# |
| Delay in treatment days | 5±2.8 | 4.2±2.4 | 0.02# |
| Adequate antibiotic treatment | 124/127 (97.6) | 113 (100) | 0.2 |
| Days of treatment | 16.9±6.1 | 14.76±2.5 | 0.001# |
| Treatment with macrolides | 77/124 (62.1) | 109 (96.4) | 0.001# |
| versus quinolones | 47/124 (37.9) | 4 (3.5) | |
| Time to apyrexia h | 59.7±67.4 | 57.8±30.8 | 0.80 |
| Complications | 75 (54.3) | 37 (32.7) | 0.001# |
| Respiratory failure | 70 (50.7) | 37 (32.7) | 0.006# |
| Mechanical ventilation | 15 (10.9) | 4 (3.5) | 0.03# |
| Acute renal failure | 10 (7.4) | 0 | 0.002# |
| Septic shock | 11 (8) | 2 (1.8) | 0.04# |
| Evolution | |||
| Cure | 128 (92.6) | 111 (98.2) | |
| Death related to pneumonia | 8 (5.9) | 2 (1.8) | 0.1 |
| Recurrence | 2 (1.5) |
Data are presented as n (%) and mean±sd. ICU: intensive care unit. #: Statistical significance in univariate analysis.