Recovered microorganisms according to the risk factors identified in multivariate analysis
| Age ≥70 yrs | p-value# | Renal comorbidity | p-value# | Cardiac comorbidity | p-value# | Infiltrates other than alveolar | p-value* | Total population | |
| With aetiology | 52/100 (52) | 4/14 (29) | 12/34 (35) | 30/60 (50) | 122/204 (60) | ||||
| Streptococcus pneumoniae | 17/52 (33) | 0.840 | 3/4 (75) | 0.100¶ | 2/12 (17) | 0.509¶ | 5/30 (17) | 0.114 | 38/122 (31) |
| Haemophilus influenzae | 5/52 (10) | 0.966 | 0/4 (-) | 1.0 | 0/12 (-) | 0.597¶ | 4/30 (13) | 0.522 | 12/122 (10) |
| Moraxella catarrhalis | 1/52 (2) | 1.0¶ | 0/4 (-) | 1.0¶ | 2/12 (17) | 0.046¶ | 0/30 (-) | 1.0¶ | 2/122 (2) |
| Gram-positive cocci+ | 3/52 (6) | 1.0¶ | 0/4 (-) | 1.0¶ | 1/12 (8) | 0.581¶ | 2/30 (7) | 1.0¶ | 8/122 (7) |
| Gram-negative rods§ | 5/52 (10) | 0.718 | 0/4 (-) | 1.0¶ | 0/12 (-) | 0.367¶ | 3/30 (10) | 1.0¶ | 14/122 (12) |
| Atypicalƒ | 10/51 (20) | 0.628 | 1/4 (25) | 1.0¶ | 6/12 (50) | 0.049 | 8/30 (27) | 0.668 | 28/122 (23) |
| Legionella pneumophila | 4/52 (8) | 1.0¶ | 0/4 (-) | 1.0¶ | 1/12 (8) | 1.0¶ | 4/30 (13) | 0.479¶ | 11/122 (9) |
| Others** | 4/52 (8) | 1.0¶ | 0/4 (-) | 1.0¶ | 0/12 (-) | 1.0¶ | 4/30 (13) | 0.287¶ | 9/122 (7) |
Data are presented as n/total n (%)
#: p-value compared to the larger population
¶: Fisher's exact test
+: Staphylococcus aureus, Streptococcus viridans, and Streptococcus pyogenes
§: Pseudomonas spp., Klebsiella pneumoniae, and Escherichia coli
ƒ: Chlamydia spp., Coxiella spp., and Mycoplasma pneumoniae
**: Mycobacterium tuberculosis, Aspergillus fumigatus, Eikenella corrodens, and viruses