Pathology and physiology
Urethritis is an inflammatory condition that may be caused by an infection or by trauma. Urinary tract infections are typically sexually transmitted and are classified as either GU (i.e., infections caused by Neisseria gonorrhoeae) or NGU (e.g., infections caused by Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum, Trichomonas vaginalis, or Mycoplasma genitalis). (3)
The presence of Gram-negative intracellular diplococci in a urethral smear is indicative of gonococcal urethritis. Chlamydial infections account for 15% to 40% of nongonococcal urethritis (NGU) cases, which are typically accompanied by gonococcal infections. It is essential to document chlamydial infections in order to prevent complications and evaluate partners, especially female partners, with chlamydial infections.
Mycoplasma genitalium-induced urethritis has become the second most prevalent cause of non-genital urethritis, despite the absence of FDA-approved detection assays.
Sexual transmission accounts for 15%-25% of NGU cases in the United States, and should be suspected when recurrent or persistent urethritis is present.
Patients who engage in oral intercourse without protection are more likely to contract NGU due to Haemophilus species. Herpes simplex virus types 1 and 2, lymphogranuloma venereum, adenovirus, mycobacterial infection, syphilis, Corynebacterium, and other bacterial infections associated with cystitis (typically gram-negative rods) while the urethral stricture is present are uncommon infectious causes of urethritis. (4)
In addition to viral and streptococcal infections, urethritis has also been linked to anaerobic and meningococcal infections. In 35% of cases, however, non-pathogenic organisms can still infect NGUs.
Post-traumatic urethritis can occur in 2% to 20% of patients undergoing intermittent catheterization and after the insertion of an instrument or foreign body. Latex catheters are 10 times more likely to cause urethritis than silicone catheters.
