In vivo whole animal body imaging reveals colonization of Chlamydia muridarum to the lower genital tract at early stages of infection.

Purpose: The leading cause of sexually transmitted bacterial infection is Chlamydia trachomatis. The aim of this study is to investigate the early events in colonization of this bacterium within the murine genital tract.

Procedures: An in vivo animal body imaging technology was used to track fluorophore labeled C. muridarum elementary bodies (EBs) inoculated intravaginally in C57BL/6 mice during the first 24 h of infection.

Results: Ascension of viable EBs was observed (1) to be localized to the lower regions of the murine genital tract within the first 24 h post challenge and (2) was dose independent during this early exposure period. Molecular detection revealed enhanced bacterial load in lower regions of the genital tract with increasing bacterial load in the upper region beginning 12 h post inoculation.

Conclusion: This study provides additional insight into chlamydial colonization in the murine genital tract during the first 12-24 h following inoculation.