Chlamydia trachomatis OmpA genotyping as a tool for studying the natural history of genital chlamydial infection.

Objective: To investigate the relationship of Chlamydia trachomatis (CT) outer membrane protein A (OmpA) type to the clearance of CT infection before treatment.

Methods: CT OmpA genotyping, with amplification and sequencing of ompA, was utilised to study the natural history of CT infection (spontaneous resolution vs persistence) in 102 individuals with chlamydia-positive screening tests returning for treatment.

Results: CT OmpA distribution was associated with spontaneous resolution of CT, most notably with CT OmpA genotype J/Ja detected more often from the initial screening CT test than other genotypes in those who then had spontaneous resolution of CT noted at the time of treatment. Five individuals with presumed persisting CT infection had discordant CT OmpA genotypes at the screening and treatment visits, suggesting possible new interval CT infection.

Conclusions: Clearance of chlamydia by the host before treatment may be influenced by the CT OmpA genotype infecting the host. CT OmpA genotyping may be a valuable tool in understanding the natural history of chlamydial infections.