What are the causes of nongonococcal urethritis (NGU)?

Updated: Dec 12, 2018
  • Author: Martha K Terris, MD, FACS; Chief Editor: Edward David Kim, MD, FACS  more...
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Commonly identified causes of NGU include the following:

  • Chlamydia trachomatis (15-55% of cases)

  • Ureaplasma urealyticum (40-60% of cases)

  • Mycoplasma genitalium (15-20% of cases)

  • Trichomonas vaginalis (<5% of cases)

The number of fastidious organisms implicated in NGU is increasing and includes several Ureaplasma and Mycoplasma species. The causative organism cannot be identified in most patients with NGU.

Rare cases may be related to lymphogranuloma venereum, herpes simplex, syphilis, mycobacteria, or urinary tract infection with urethral stricture. Other rare but reported causes of NGU include anaerobes, adenovirus, cytomegalovirus, and streptococcus.

Urethritis following catheterization occurs in 2-20% of patients practicing intermittent catheterization and is 10 times more likely to occur with latex catheters than with silicone catheters.

Polymicrobial NGU and cases of urethritis due to both gonococcal infection and nongonococcal factors are possible and can explain some treatment failures. This should also be considered in patients with HIV infection.

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