[Action of penicillin on the causative agent of paratrachoma in the dynamics of an in vitro infection].

Monolayer cultures of L-cells (mouse fibroblasts) were inoculated with the causative agent of paratrachoma (strain LB-I). Simultaneously penicillin in doses of 0.01, 0.1, 1, 10, 25, 50, 100, 150 and 200 microgram/ml was added and its effect on the causative agent in the infection dynamics (18, 24, 48 and 72 hours after the inoculation) was studied with the light and electron microscopes. Gradual changes in the ultrastructure of the vegetative forms were observed by the 24th hour with the use of penicillin in a dose of 0.01 microgram/ml: the size of the vegetative forms increased, the cell wall membranes separated and periplasmic space significantly enlarged, the protoplast fragments disjoined into it, large forms vacuolized and were fragment with membranes, sometimes multilayer ones. When the culture was exposed to large doses of penicillin, the rate of the changes in the structure was higher and they were simultaneously of several types. Various types of the changes and possible modes of their formation were analyzed. Morphologically they are similar to the processes observed in L-transformation of bacteria. However, these structures were not infectious.