Table 3.
Patients with CAP and episodes of CAP with a pathogen identified
| Aetiology | Patients with pathogen identifieda | Episodes with pathogen identifieda | References | ||||
|---|---|---|---|---|---|---|---|
| Cohorts (n)b | Studies (n) | Range (%) | Cohorts (n)b | Studies (n) | Range (%) | ||
| Gram-positive bacteria | |||||||
| Streptococcus pneumoniae | 51 | 19 | 12.0–85.0 | 6 | 5 | 3.2–19.2 | [22–26, 33–43, 45, 46, 48–50, 65, 67, 68] |
| Staphylococcus aureus | 39 | 12 | 0.8–20.0 | 2 | 2 | 3.3–6.5 | [22, 23, 26, 33, 36, 38, 40–42, 46, 49, 50, 65, 67] |
| Streptococcus viridans | 1 | 1 | 1.7 | 1 | 1 | 3.3 | [22, 36] |
| Gram-negative bacteria | |||||||
| Gram-negative enteric bacillic | 39 | 10 | 0.6–42.9 | 3 | 2 | 1.7–7.8 | [22, 23, 25, 34, 37, 40, 41, 45, 46, 48–50] |
| Haemophilus influenzae | 45 | 15 | 1.1–29.4 | 6 | 5 | 3.2–19.2 | [22, 23, 25, 26, 33–43, 45, 46, 48–50, 65] |
| Pseudomonas aeruginosa | 14 | 10 | 0.9–16.8 | 2 | 2 | 5.9–6.7 | [22, 24, 26, 34, 36, 38, 41–43, 45, 49, 67] |
| Pseudomonas speciesd | 19 | 1 | 0.2–3.2 | 1 | 1 | 19.4 | [33, 41] |
| Klebsiella pneumoniae | 5 | 5 | 0.3–5.0 | 1 | 1 | 3.3 | [24, 26, 36, 38, 42, 43] |
| Moraxella catarrhalis | 28 | 5 | 0.3–2.3 | 0 | 0 | – | [26, 40–42, 46] |
| Serratia marcescens | 1 | 1 | 2.3 | 1 | 1 | 3.3 | [26, 36] |
| Escherichia coli | 5 | 3 | 0.6–2.1 | 1 | 1 | 6.7 | [36, 38, 42, 43] |
| Atypical bacteria | |||||||
| Mycoplasma pneumoniae | 39 | 10 | 0.7–61.3 | 0 | 0 | – | [22, 23, 38–43, 45, 65] |
| Legionella pneumophila | 19 | 12 | 1.7–20.1 | 5 | 4 | 3.2–15.1 | [22, 25, 26, 34–36, 38–40, 42, 43, 45, 46, 48–50] |
| Legionella speciese | 27 | 3 | 5.4–20.0 | 0 | 0 | – | [23, 41, 67] |
| Chlamydophila pneumoniae | 29 | 9 | 0.1–9.9 | 0 | 0 | – | [22, 23, 26, 38, 39, 41–43, 45] |
| Coxiella burnetii | 9 | 6 | 0.8–3.4 | 0 | 0 | – | [22, 26, 38, 40, 43, 45] |
| Virus | 38 | 10 | 1.4–28.6 | 1 | 1 | 0.7 | [22, 23, 38, 40–42, 45, 46, 48, 49, 65] |
CAP community-acquired pneumonia
Pathogens only reported in one cohort in one study were excluded
aPercentages are based on the number of patients/episodes in which pathogens were identified and data were available
bFor studies that only reported data separately for each cohort, all cohorts were included; for studies that reported data for the overall study population, the summary data were used. Studies performed in patients with pneumonia due to a specific pathogen were excluded
cFor studies [22, 23, 25, 34, 37, 40, 41, 45, 46, 48–50], Gram-negative enteric bacilli were grouped together and individual pathogens in this group were not reported separately
dFor studies [33, 41], Pseudomonas species were not reported separately and, therefore, could include P. aeruginosa
eFor studies [23, 41, 67], Legionella species were not reported separately and, therefore, could include L. pneumophila