Abstract:

Objective To observe the ultrastructural changes of Chlamydia trachomatis after treatment with azithromycin. Methods The Chlamydia trachomatis laboratory strain （D/UW-3/Cx） was cultured in McCoy cells with or without the presence of azithromycin of 0.0667, 0.1340, 0.1900, 0.2680 and 0.3330 mg/L for 48 hours. The ultrastructural changes of host cells and Chlamydia trachomatis were observed by transmission electron microscopy. Results After 48-hour culture, vesicles increased in number both inside and outside of the inclusion bodies with the rise in azithromycin concentration; there were abnormally large reticulate bodies, some of which experienced abnormal division and even necrosis or breakdown; the number of elementary bodies was decreased, while their size was enlarged, with a more wrinkled outer membrane. No inclusion bodies were seen when the concentration of azithromycin was 0.333 mg/L. Conclusions Azithromycin can induce an increment in the outer membrane of Chlamydia trachomatis, formation of vesicles, abnormal enlargement or breakdown of reticulate bodies, and a decrease in elementary bodies.

Key words: ultrastructure