In vitro activity of tosufloxacin (A-60969) and clarithromycin (A-56268, TE-031) against resistant Haemophilus influenzae, Streptococcus pneumoniae and Branhamella catarrhalis isolates.

The activity of tosufloxacin (A-60969), a new oral quinolone, and clarithromycin (A-56268, TE-031), a new oral macrolide, was compared in vitro to that of other oral quinolones and beta-lactam antimicrobial agents against clinical isolates of ampicillin and/or chloramphenicol resistant Haemophilus influenzae, penicillin resistant Streptococcus pneumoniae and beta-lactamase producing Branhamella catarrhalis. Results were compared to those for sensitive isolates. Tosufloxacin was the most active compound against Haemophilus influenzae and was more active than ciprofloxacin or ofloxacin against all strains of Streptococcus pneumoniae. Tosufloxacin was also more active than any of the beta-lactam drugs tested against penicillin resistant or relatively penicillin resistant isolates. Clarithromycin was the most active compound tested against both penicillin sensitive and penicillin resistant Streptococcus pneumoniae, and was as active as ciprofloxacin against Branhamella catarrhalis. In view of the favourable in vitro activity against common bacterial respiratory pathogens, tosufloxacin should be considered for clinical trials in adults with respiratory tract infections, while clarithromycin might be useful in treatment of infection with these organisms in all age groups.