Inhibition of Chlamydia trachomatis growth in mouse fibroblasts by liposome-encapsulated tetracycline

The in-vitro susceptibility of Chlamydia trachomatis to liposome-encapsulated tetracycline was determined and compared with free tetracycline. Anionic, cationic and neutral small unilamellar liposomes were used in this study. Chlamydia-infected mouse fibroblast monolayers were continuously exposed to varying concentrations of antibiotic, incubated for 48 h and Giemsa stained. The minimum inhibitory concentration (MIC) for anionic, cationic and neutral liposomes containing tetracycline were 0.38, 0.08 and 0.04 mg/L, respectively. This was approximately 2, 10, and 20 times more efficient than free tetracycline (MIC, 0.79 mg/L). Neutral liposomes displayed no visible toxic side-effects on the host cells. When compared with free tetracycline, neutral liposomes were the most efficient for the delivery of inhibitory concentrations of tetracycline to chlamydia-infected mouse fibroblast L cell cultures.