Activity of doxycycline against respiratory pathogens.

149 patients were admitted from the Brussels area to the multi-centre Pan European trial of doxycycline in respiratory tract infections. Of these, 40 satisfied the strict criteria for detailed bacteriological study with positive culture of a known pathogen before treatment and bacteriological follow-up after treatment. The pathogens were beta-haemolytic streptococcus, group A (29 cases), pneumococcus (6 cases) and Haemophilus influenzae (6 cases); in one case, the pneumococcus and H. influenzae were present together. The results of doxycycline therapy were excellent, this included both its in vivo and in vitro activity; only one strain of pneumococcus proved resistant.