Microbiological etiology in clinically diagnosed community-acquired pneumonia in primary care in Orebro, Sweden

Objective To study the etiology of clinically diagnosed community-acquired pneumonia (CAP) in antibiotically naive patients attending a primary care center and treated at their homes. Methods A three-year prospective study was carried out, and 177 patients presenting with clinical signs of CAP were included. All patients had chest X-rays after inclusion, and 82 (46%) showed infiltrates. Nasopharyngeal swab culture was performed on all patients, and 51% produced a representative sputum sample. Paired sera were obtained from 176 patients. Results Among the 82 patients with radiographically proven CAP, Streptococcus pneumoniae was detected in 26 patients (32%), Haemophilus influenzae in 23 (28%), Mycoplasma pneumoniae in 15 (18%), and Chlamydia pneumoniae in four (5%). Serologic evidence of a viral infection was found in 13 patients (16%). Among the 95 patients without infiltrates, S. pneumoniae was found in 21 (22%), H. influenzae in 14 (15%), M. pneumoniae in two (2%), and C. pneumoniae in five (5%). Viral infection was detected in 19 (20%) of these 95 patients. Conclusion In primary care in Sweden, the initial antibiotic treatment in any patient with pneumonia should be effective against S. pneumonia and H. influenzae . In addition, M. pneumoniae should be targeted during recurrent epidemics. C. pneumoniae , and especially Legionella , seem to be uncommon in primary care.