Non-neococcal urethritis (NSU) is called urethritis, not associated with Neisseria gonorrhoeae. This is the most common syndrome detected in STD clinics in men. The term “non-specific urethritis” is not very successful. It gives the false impression that NSU has no reason or its reason is unknown. In early studies, 30–50% of NSU cases were associated with Chlamydia trachomatis. Currently, Chlamydia trachomatis accounts for 20-30 “cases of NSU. The cause of the remaining NSUs has not been fully elucidated. Ureaplasma urealyticum is detected in 20-40% of NSU patients. However, data on the etiological role of Ureaplasma urealyticum are contradictory. About a third of NSU patients do not detect neither Chlamydia trachomatis nor Ureaplasma urealyticum.  

Recent studies indicate the possible role of Mycoplasma genitalium in the etiology of NSU. The association of NSU with oral sex in homosexuals and bisexual men suggests that part of the NSU is due to normal oropharyngeal microflora. Less than 5% of NSU cases occur in Trichomonas vaginalis and HSV. Urethritis caused by HSV is often combined with rashes on the genitals and severe pain during urination. Enterobacteria sometimes cause urethritis in homosexuals and bisexual men who practice active anal intercourse. The differential diagnosis of NSU should include foreign bodies of the urethra and periuretic fistula, which are rare.
Persistent and recurrent NSUs are difficult to treat. The effectiveness of their treatment often does not satisfy either the patient or the doctor. Persistent and recurrent NSU should be distinguished from acute NSU. Persistent and relapsing NSU are characterized by frequent exacerbations, sometimes not associated with sexual contacts. In this case, Chlamydia trachomatis and other known pathogens in most cases are not found. 

Although sometimes relapsing NSU is combined with abacterial prostatitis, most often the prostate gland is not changed. The role of alcohol, spicy foods and changes in the frequency of sexual intercourse in the development of recurrent NSU and abacterial prostatitis has not been proven. It is possible that immune responses play a role in the pathogenesis of recurrent NSU. For example, urethritis is sometimes detected in patients with Reiter’s syndrome after intestinal infections. The main complications of NSU are complications of chlamydial infection, such as acute epididymitis and Reiter’s syndrome. None of these complications occurs with nonchlamydia NSU. There is no evidence that NSU leads to urethral strictures. Most cases of urethral strictures before the discovery of antibiotics were caused by gonorrhea and complications of local treatment methods, li the absence of Chlamydia trachomatis neither acute nor recurrent HIU are associated with severe complications in either men or women – their sexual partners. Although NSU is traditionally treated with antibiotics, the question of the appropriateness of antibiotic therapy in the absence of Chlamydia trachomatis remains open.