In vitro activity of rifaximin, a topical rifamycin derivative, against Chlamydia trachomatis.

Rifaximin is a rifamycin derivative that possesses in vitro activity against a wide range of bacteria. Its antimicrobial spectrum plus poor intestinal absorption have led to consideration of this compound as a topical agent. We evaluated its in vitro activity against clinical and laboratory strains of Chlamydia trachomatis and found that rifaximin exhibits minimum inhibitory concentrations (MICs) at concentrations that would be greatly exceeded in a topical preparation.