Table 1.

Microbial Pathogens in Chronic Obstructive Pulmonary Disease (COPD)

Microbe	Role in exacerbations	Role in stable disease
Bacteria
Haemophilus influenzae Streptococcus pneumoniae Moraxella catarrhalis Pseudomonas aeruginosa Enterobacteriaceae Haemophilus haemolyticus Haemophilus parainfluenzae Staphylococcus aureus	20–30% of exacerbations 10–15% of exacerbations 10–15% of exacerbations 5–10% of exacerbations, prevalent in advanced disease Isolated in advanced disease, pathogenic significance undefined Isolated frequently, unlikely cause Isolated frequently, unlikely cause Isolated infrequently, unlikely cause	Major pathogen Minor role Minor role Likely important in advanced disease Undefined Unlikely Unlikely Unlikely
Viruses
Rhinovirus Parainfluenza Influenza Respiratory syncytial virus Coronavirus Adenovirus Human metapneumovirus	20–25% of exacerbations 5–10% of exacerbations 5–10% of exacerbations 5–10% of exacerbations 5–10% of exacerbations 3–5% of exacerbations 3–5% of exacerbations	Unlikely Unlikely Unlikely Controversial Unlikely Latent infection seen, pathogenic significance undefined Unlikely
Atypical Bacteria
Chlamydophila pneumoniae Mycoplasma pneumoniae	3–5% of exacerbations 1–2% of exacerbations	Commonly detected, pathogenic significance undefined Unlikely
Fungi
Pneumocystis jiroveci	Undefined	Commonly detected, pathogenic significance undefined

NOTE. Reproduced with permission from Sethi S, Murphy TF. Infection in the pathogenesis and course of chronic obstructive pulmonary disease. N Engl J Med. 2008;359[22]:2355–65. ©Massachusetts Medical Society, 2008