In vitro activity of iclaprim and comparison agents tested against Neisseria gonorrhoeae including medium growth supplement effects.

Iclaprim is a novel diaminopyrimidine currently in phase III clinical development. This study was conducted to determine the activity of iclaprim compared with trimethoprim and other commonly prescribed drug classes against a comprehensive collection of 156 Neisseria gonorrhoeae, including subsets of organisms resistant to beta-lactams and fluoroquinolones (>60%). Iclaprim (MIC(50/90), 4/8 microg/mL) was 16-fold more potent than trimethoprim (MIC(50/90), 64/>64 microg/mL), and medium growth supplements did not adversely influence activity. Lack of cross-resistances for iclaprim with other commonly used therapies could make iclaprim an alternative for several sexually transmitted diseases (gonococci, Chlamydia trachomatis).