Chlamydia trachomatis as the cause of infectious infertilityÖ Acute, repetitive or persistent long-term infection?

Chlamydia trachomatis is the most frequently detected agent of sexually transmitted infections worldwide. Infection of the lower female genital tract (FGT) can cause cervicitis and if ascending to the upper FGT may result in serious sequelae such as pelvic inflammatory disease (PID), salpingitis and tubal factor infertility (TFI). The factors leading to this complication are still not completely understood. We elaborate four different models for host–pathogen interactions in C. trachomatis infections that may promote disease development: (1) acute infection, (2) repeated infections, (3) chronic/persistent infections and (4) non-inflammatory colonization. Whereas experimental data exist for all of these models in vitro, ex vivo and in vivo, we were interested in seeing what clinical evidence we have supporting one or the other model. We particularly focused on data that favour the one or the other model for TFI development in C. trachomatis infection and speculate on future studies that could integrate in vitro findings for a better characterization of the situation in vivo.