Urethritis is an inflammation of the genital tract that is mostly due to infectious causes. Its pathogenesis depends on the causative pathogen. N. gonorrhea is usually transmitted via the genital tract to the human host. Following attachment to host cell, which is mediated by pili, gonococci become engulfed in a process known as parasite-directed endocytosis. This organism will survive inside the vacuoles and replicate. Among non-gonorrheal causes, Chlamydia trachomatis is the most common. The infectious process begins with cell surface attachment and phagocytosis by the host cell. The pathogen survives inside the cell by debilitating the cellular lysosomes and replicating as elementary bodies which is considered as the infective form of the pathogen.

Urethritis is divided into gonorrheal and non-gonorrheal causes. The pathophysiology of each one of them is different.

• N. gonorrhea is usually transmitted via the genital tract to the human host.
• Following attachment to host cell, which is mediated by pili, gonococci become engulfed in a process known as parasite-directed endocytosis. This organism will survive inside the vacuoles and replicate.^[1]
• Gonococcal virulence factors include:^[2][3][4]
  • Pili
  • The ability to attach to urethral epithelial cells
  • Production of extracellular proteases that cleave IgA

• Among non-gonorrheal causes, Chlamydia trachomatis is the most common.
• The infectious process begins with cell surface attachment and phagocytosis by the host cell. The pathogen survives inside the cell by debilitating the cellular lysosomes and replicating as elementary bodies which is considered as the infective form of the pathogen.^[5][6]

Urethritis does not follow any genetic pattern.

• Stevens-Johnson syndrome
• Nongonococcal urethritis (NGU) due to C. trachomatis may be associated with:
  • Epididymitis
  • Prostatitis
  • Reactive arthritis
• HIV transmission is facilitated by co-existing non-gonococcal urethritis, however treatment of NGU is the same in HIV negative or positive patients.

On gross pathology, mucoid, mucopurulent, or purulent discharge can be observed.

Characteristic findings include:^[7]

• Gram-negative intracellular diplococci (GNID) or purple intracellular diplococci on methylene blue, or gentian violet stain.
• Invaded epithelial cells
• Vacuoles that contain multiple organisms
• Polymorphic nuclear cellss

• Absence of gram-negative intracellular diplococci (GNID)
• Signs of inflammation present