Evaluation of In Vitro Activity of Rokitamycin against Chlamydia trachomatis
1990 Volume 64 Issue 6 Pages 687-692
Details
1990 Volume 64 Issue 6 Pages 687-692
Evaluation of the in vitro activity of rokitamycin (RKM) against Chlamydia trachomatis in cycloheximide treated HeLa 229 cells and McCoy cells by comparing with five drugs including doxycycline (DOXY), minocycline (MINO), ofloxacin (OFLX), ampicillin (ABPC) and erythromycin (EM) with regard to assaying minimal inhibitory concentrations (MICs), minimal lethal concentrations (MLCs), and by yield reduction assays:
1) direct treatment of Chlamydial organisms with various concentrations of antibiotics before inoculation, 2) pre-treatment of host cell (HeLa 229) with the antibiotics before they are infected and 3) treatment of already infected cultures (48 hrs after infection) with antibiotics. The yield of Chlamydia was determined by both assaying the infectivity of Chlamydia and/or Chlamydiazyme® value (from Abott Co Ltd USA).
It was found that similar MIC was obtained among the drugs tested (except EM) in both HeLa 229 cell and McCoy cell assay system. The MLC of RKM (0. 3μg/ml) was the same as that of OFLX and was significantly lower than that of other drugs tested.
When Chlamydial organisms and the host cells were treated with various concentrations (25-0.1μg/ml) of the drug, the infectivity and the growth of Chlamydia was noteworthily decreased with RKM treatment. Infectivity of Chlamydia in an already infected cultures also decreased with RKM treatment within 24 hours when comparing the value of the control. In other drugs treatment, 96 hours or more hours were required for obtaining the same infectivity as RKM. Although the Chlamydiazyme® value of the control culture (no drug) gradaully increased, the values of drug-treated samples (infected cell+fluid) did not changed within the time tested: just before and 24, 48, 72 an 96 hours after treatment with drugs. This suggests that RKM permiates both host and Chlamydial cells and results in strong bactericidal activity. These in vitro results make us expect that RKM will be an excellent antimicrobial agent for therapy of the patients with Chlamydial infection.
