[Comparative in vitro activity of a new macrolide RU 28965 and of erythromycin against Chlamydia trachomatis].

Activity of a new macrolide, RU 28965, and erythromycin against 8 Chlamydia trachomatis strains isolated from the human genital tract was studied. Minimal inhibitory concentrations were determined using cycloheximide-treated McCoy cells. Giemsa and immunofluorescence staining with monoclonal antibodies were used to detect Chlamydial inclusions. Immunofluorescence proved more sensitive and easier to read. All the strains were highly susceptible to RU 28965 (MIC = 0.05 mg/l - 0.1 mg/l) and erythromycin (MIC = 0.02 mg/l - 0.2 mg/l).