Doxycycline in respiratory infections: a re-assessment after 17 years.

Seventeen years after a previous study of doxycycline in acute purulent exacerbations of chronic bronchitis, a similar investigation was repeated. Forty patients with bacteriologically proven infections were given 100 mg doxycycline twice daily (by mouth) for ten days. The clinical results in Branhamella catarrhalis infections were excellent as were those with Streptococcus pneumoniae, but one patient developed septicaemia with a resistant pneumococcus while under therapy. Treatment was unsuccessful in a third of the patients with Haemophilus influenzae infections. Overall, excellent or good results were recorded in 74% of patients at the end of treatment, and in 64% a week later. Doxycycline is still a useful oral antibiotic in this condition and possibly the best for B. catarrhalis infections, especially with beta-lactamase producing strains.