Final answer:
Chlamydial infection is the most common cause of non-gonococcal urethritis. Chlamydia trachomatis causes most cases of this condition, which can lead to further health complications if left untreated.
Step-by-step explanation:
Non-gonococcal urethritis is most often caused by chlamydial infection. It refers to the inflammation of the urethra that is not linked to Neisseria gonorrhoeae, which causes gonorrhea. The primary causative agent of non-gonococcal urethritis is Chlamydia trachomatis, which can also lead to other complications such as epididymitis, pelvic inflammatory disease (PID), and an increased risk of cervical cancer. While Mycoplasma genitalium is another common cause and can result in recurrent or persistent infections, chlamydial infection remains the most prevalent. Both conditions, urethritis and prostatitis, can present with similar symptoms such as painful urination and genital discharge, making clinical diagnosis and treatment a coordinated effort to manage the infection effectively.