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What Causes Gonorrhea?

By Dr Ananya Mandal, MD

Gonorrhoea is a sexually transmitted infection (STI) caused by the Neisseria gonorrhoeae bacteria. The bacteria is also known as gonococcus.

The bacteria and its family

Neisseria gonorrhoeae is a Gram-negative diplococcus. This means it is usually seen in pairs with the adjacent sides flattened. It is pathogenic to humans who are its only natural host. This infection does not affect animals.

Pathogenesis of gonorrhea

Gonococcus is present in the penis and vaginal fluids and discharge of an infected person. The bacteria can spread from person to person via these fluids. It is capable of infecting mucous membranes of the urethra, endocervix (inner walls of the cervix), rectum, pharynx (back of the throat) and conjunctiva (mucous linings of the eyes).

Gonorrhea is a sexually transmitted disease of worldwide importance. It commonly affects young sexually active persons between ages 15 and 29 years of age.

Gonococcus can grow and multiply easily in warm, moist areas. This includes the cervix, uterus, and fallopian tubes in women, and in the urethra in women and men. The bacterium can also grow in the mouth, throat, eyes, and anus. 

Men have a 20% risk of getting the infection from a single act of vaginal intercourse with a woman infected with gonorrhoea and women have a 60–80% risk of getting the infection from a single act of vaginal intercourse with a man infected with gonorrhea. The risk for men who have sex with men is higher.

Spread can occur during unprotected sexual intercourse with an infected person. Ejaculation is not needed for successful transmission. Spread may also occur by sharing contaminated and unsheathed (by condom) sex toys and vibrators. Gonococcus can also spread from a pregnant mother to her new born infant during childbirth. This may affect the baby’s eyes and conjunctiva and is called ophthalmia neonatorum.

The incubation period is 2 to 30 days with most symptoms occurring between 4–6 days after being infected. Once infected, the gonococcus bacterium attaches to the urethral mucosal layer and penetrates within using pili and opa proteins. Infection leads to inflammation of the urethra (urethritis), cervix (cervicitis), fallopian tubes (salpingitis), rectum (proctitis), conjunctiva (conjunctivitis), pharynx (pharyngitis) and pelvic inflammatory disease,

Risk factors of gonorrhoea infection

Risk factors that predispose to a gonococcal infection include:

  • young age of less than 25 years
  • number of sexual partners
  • previous history of STI and presence of other STIs and HIV infection
  • lack of barrier contraception with infected partners, new partners, multiple or unknown sexual partners
  • homosexual men who indulge in unprotected anal intercourse of oral sex with multiple or unknown male partners
  • history of commercial sexual activity and drug use
  • some ethnic groups and population mobility

Reviewed by , BA Hons (Cantab)

Further Reading

Last Updated: Nov 28, 2012

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