For treatment purposes, doctors usually classify infectious urethritis in two categories: gonococcal urethritis, caused by gonorrhea bacteria; and non-gonococcal urethritis (NGU), caused by bacteria other than gonorrhea bacteria.
The symptoms of urethritis can include pain or a burning sensation upon urination (dysuria), a white/cloudy discharge and a feeling that one needs to pass urine frequently; however, there are often no symptoms.
Urethritis can be caused by mechanical injury (from a urinary catheter or a cytoscope), by an irritating chemical (antiseptics or some spermicides), or by an infection (most commonly sexually transmitted).
The most common bacterial cause of NGU is chlamydia trachomatis, but it can also be caused by Ureaplasma urealyticum, Trichomonas vaginalis (rare), Herpes simplex virus (rare), Adenovirus, Haemophilus vaginalis, and Mycoplasma genitalium.
Historically, it has been easy to test for the presence of gonorrhea by viewing a Gram's stain of the urethral discharge under a microscope: the causative organism is distinctive in appearance. Thus, one of the major causes of urethritis can be identified by a simple common test, and the distinction between gonococcal and non-gonococcal urethritis arose historically for this reason.
Non-gonococcal urethritis (NGU) is diagnosed if a person with urethritis has no signs of gonorrhea bacteria on laboratory tests. The most frequent cause of NGU (23%-55% of cases) is chlamydia.
Because of its multi-causative nature, initial treatment strategies involve using a broad range antibiotic that is effective against chlamydia (such as doxycycline). It is imperative that both the patient and any sexual contacts are treated. Women who are infected with the organisms that cause NGU may develop pelvic inflammatory disease. If symptoms persist, follow-up with a urologist may be necessary to identify the cause.