Infectious diseases that result in slowly resolving and chronic pneumonia.

Familiarity with the natural history of common pneumonias is obligatory for the clinician to determine whether a specific case of pneumonia is resolving at the expected rate. To many clinicians, the term slowly resolving pneumonia conjures an association with underlying neoplasm and/or less common pathogens. In reality, host factors or common pathogens such as Streptococcus pneumoniae and Legionella pneumophila are more likely responsible for delayed resolution. Familiarity with the pattern of resolution of pneumonias caused by these organisms should allow the clinician to follow such patients and avoid premature invasive evaluation. In contrast, Mycoplasma pneumoniae and Chlamydia species rarely result in slowly resolving pneumonia. Chronic bacterial pneumonia is an infectious syndrome that may present in the absence of systemic symptoms. The presentation is varied and may mimic neoplasm, interstitial lung disease, or chronic fungal or mycobacterial infection. Bacteria most commonly associated with chronic pneumonia include Haemophilus influenzae, Staphylococcus aureus, alpha-hemolytic streptococci (not S pneumoniae), and Pseudomonas aeruginosa.