An in vitro model of azithromycin-induced persistent Chlamydia trachomatis infection

Single-dose azithromycin is recommended for treating Chlamydia trachomatis infections. Here, we established an in vitro cell model of azithromycin-induced persistent infection. Azithromycin inhibited the replication of C. trachomatis in a dose-time-dependent manner. Electron microscopy indicated that small inclusions in the induced model contained enlarged, aberrant and non-infectious reticulate bodies. RT-PCR showed that C. trachomatis still has the ability to express the unprocessed 16S rRNA gene in the model and that C. trachomatis recovered after the removal of azithromycin with a peak recovery time of 24 h. The mutations in 23S rRNA, L4 and L22 genes were not found in persistent infection, and qRT-PCR analysis showed that the relative expression level of euo in azithromycin treated infection was upregulated while omcB was downregulated. In summary, this study provides a novel in vitro cell model to examine the characteristics of azithromycin-induced persistent infection and contribute to the development of treatments for C. trachomatis infection.