PATHOGENS

• Gonococcal urethritis:5-20%
  • Neisseria gonorrhoeae: 5-20% of urethritis in the U.S. (higher in inner-city populations).
• Non-gonococcal urethritis:
  • Chlamydia trachomatis (CT): the most frequent cause of urethritis in men accounting for 23%-55% of cases. However, the proportion of non-gonococcal urethritis (NGU) cases due to CT is declining gradually.
  • Mycoplasma genitalium: maybe the second most frequent cause of urethritis in the U.S and U.K. May account for between 15%-22% of cases of acute NGU. Also has a role in chronic NGU.
  • Trichomonas vaginalis: is the cause of only about 2% of cases of acute NGU but probably a higher proportion of chronic NGU.
  • Ureaplasma urealyticum: biovar 2 is probably a more important cause of acute NGU than previously realized. Note that organism can be cultured from 30-40% of asymptomatic men. Quantification of the organism may help establish a diagnosis (Frolund Sex Transm Infect 2011).

• Less common: include
  • Herpes simplex virus (rare in absence of obvious skin lesions)
  • Adenovirus
  • Haemophilus spp
  • Yeasts, e.g., Candida spp.
  • N. meningitidis 
  • Staphylococcus saprophyticus.  
  • Novel bacteria recently associated with bacterial vaginosis such as Leptotrichia/Sneathia spp. may be the urethral pathogens of "idiopathic" NGU[9].