Which sexually transmitted infection is most commonly associated with pelvic inflammatory disease (PID)?

Pelvic inflammatory disease (PID) is primarily the result of infections that ascend from the cervix and vagina into the upper reproductive tract, namely the uterus, fallopian tubes, and ovaries. The two most commonly implicated pathogens in this process are Chlamydia trachomatis and Neisseria gonorrhoeae.

Chlamydia is noted for causing asymptomatic infections in many cases, which can lead to delayed diagnosis and treatment; subsequently, this increases the risk for developing PID. Gonorrhea has similar characteristics and can also progress to PID if left untreated. The relationship between these infections and PID is well-established in clinical studies, where it has been shown that a significant proportion of PID cases are attributable to either chlamydial or gonococcal infections.

Other infections such as HPV, syphilis, and herpes simplex virus do not have a direct established causative link to PID. While these infections can lead to various reproductive complications, they are not the primary pathogens associated with the development of pelvic inflammatory disease. Thus, Chlamydia and gonorrhea are clearly recognized as the most common sexually transmitted infections associated with PID, confirming the selection of that answer.