Aetiology of lower respiratory tract infection in adults in primary care: a prospective study in 11 European countries

Objectives: To describe the role of bacteria (including bacterial resistance), viruses (including those recently described), and mixed bacterial-viral infections in adults presenting to primary care with lower respiratory tract infection (LRTI). Methods: We enrolled 3104 adults with LRTI, 141 (4.5%) of whom had community-acquired pneumonia (CAP), and 2985 matched controls in a prospective study in 16 primary care networks in Europe, and followed patients up at 28-35 days. We detected S. pneumoniae and H. influenzae and assessed susceptibility, atypical bacteria and viruses. Results: A potential pathogen was detected in 1844 (59%) (in 350 (11%) bacterial pathogens only, in 1190 (38%) viral pathogens only, and in 304 (10%) both bacterial and viral pathogens). The most common bacterial pathogens isolated were S. pneumoniae (5.5% overall, 9.2% in CAP patients) and H. influenzae (5.4% overall, 14.2% in CAP patients).