Final answer:
Chlamydia trachomatis is the most likely causative pathogen in a 26 year old woman with PID.
Step-by-step explanation:
The most likely causative pathogen in a 26 year old woman with Pelvic Inflammatory Disease (PID) is Chlamydia trachomatis. Chlamydia trachomatis is one of the two most common pathogens responsible for PID, along with Neisseria gonorrhoeae. PID is an infection of the female reproductive organs, and symptoms include pain in the lower abdomen, vaginal discharge, fever, and painful urination. It is important to seek medical attention and receive appropriate treatment for PID to prevent complications and long-term consequences.