Ultrastructural analysis of the effects of erythromycin on the morphology and developmental cycle of Chlamydia trachomatis HAR-13.

The effect of erythromycin (10 micrograms/ml) on the morphology and developmental cycle of Chlamydia trachomatis HAR-13 was examined by electron microscopy. When the antibiotic was added later than 24 h post infection, the HAR-13 morphology or developmental cycle was not altered. Addition at 18 or 24 h post infection inhibited glycogen production, blocked the transformation of the reticulate body to elementary body, and produced ghost bodies and reticulate bodies twice the diameter of untreated reticulate bodies. When erythromycin was added within 12 h post infection, the conversion of the elementary body to reticulate body was inhibited. Erythromycin (10 micrograms/ml) was bactericidal to strain HAR-13 throughout the developmental cycle.