| 2001–2002 study# | 2009–2011 study¶ | |||
| Tests performed | Positive results | Tests performed | Positive results | |
| Blood and serology | 238 | 75 (31.5) | 138 | 32 (23.2) |
| Blood overall | 236 | 36 (15.3) | 136 | 13 (9.6) |
| Bacterial culture | 185 | 6 (3.2) | 126 | 7 (5.6) |
| Streptococcus pneumoniae PCR | 228 | 30 (13.2) | 86 | 7 (8.1) |
| Serology overall | 181 | 49 (27.0) | 105 | 22 (21.0) |
| Acute serology | ||||
| Mycoplasma IgM antibody | 34 | 11 (32.4) | 77 | 8 (10.4) |
| ASOT | 158 | 12 (7.6) | 80 | 9 (11.3) |
| Mycoplasma/Chlamydia | 128 | 8 (6.3)/0 | 51/39 | 0 |
| Legionella/Q-fever | 0 | 0 | 50/42 | 0 |
| Influenza A/B | 158 | 1 (0.6)/2 (1.2) | 68/62 | 7 (10.3)/0 |
| RSV/adenovirus | 158 | 2 (1.2)/2 (1.2) | 52/46 | 0 |
| Convalescent serology | ||||
| ASOT | 52 | 2 (3.8) | 0 | 0 |
| Mycoplasma/Chlamydia | 14 | 3 (21.4)/0 | 0 | 0 |
| Influenza A/B | 101 | 1 (1.0)/0 | 0 | 0 |
| RSV/adenovirus | 101 | 6 (6.0)/6 (6.0) | 0 | 0 |
| Respiratory secretions overall | 175 | 59 (33.7) | 151 | 121 (80.1) |
| Viral screen | 158 | 44 (27.9) | 141 | 63 (44.7) |
| Bacterial culture (TBS) | 14 | 5 (35.7) | 12 | 7 (58.3) |
| Pleural fluids overall | 17 | 4 (23.5) | 40 | 27 (67.5) |
| Bacterial culture | 17 | 2 (11.8) | 40 | 10 (25.0) |
| Pneumococcal antigen | 17 | 2 (11.8) | 30 | 7 (23.3) |
| Pneumococcal real-time PCR | 0 | 0 | 30 | 18 (60.0) |
Data are presented as n or n (%). ASOT: antistreptolysin O titre; RSV: respiratory syncytial virus; TBS: tracheobronchial secretions. #: n=241; ¶: n=160.