Aetiology of, and risk factors for, recurrent community-acquired pneumonia.

Recurrent community-acquired pneumonia (CAP) requiring hospitalization is a matter of particular concern. However, current information on its prevalence, aetiology and risk factors is lacking. To address these issues, we performed an observational analysis of a prospective cohort of hospitalized adults with CAP. Recurrence was defined as two or more episodes of CAP 1 month apart within 3 years. Patients with severe immunosuppression or local predisposing factors were excluded. Of the 1556 patients, 146 (9.4%) had recurrent CAP. The most frequent causative organism was Streptococcus pneumoniae, both in patients with recurrent CAP and in those without recurrence. Haemophilus influenzae, other Gram-negative bacilli and aspiration pneumonia were more frequent among patients with recurrent CAP, whereas Legionella pneumophila was rarely identified in this group. Independent factors associated with recurrent CAP were greater age, lack of pneumococcal vaccination, chronic obstructive pulmonary disease (COPD) and corticosteroid therapy. In a sub-analysis of 389 episodes of pneumococcal pneumonia, the only independent risk factor for recurrence was lack of pneumococcal vaccination. Recurrence of CAP is not a rare clinical problem and it occurs mainly in the elderly, patients with COPD, and those receiving corticosteroids. Our study provides support for recommending pneumococcal vaccination for adults at risk of pneumonia, including those with a first episode of CAP.