Neisseria gonorrhoeae

Neisseria gonorrhoeae
Neisseria gonorrhoeae cultured on two different media types.
Scientific classification
Kingdom:	Bacteria
Phylum:	Proteobacteria
Class:	Beta Proteobacteria
Order:	Neisseriales
Family:	Neisseriaceae
Genus:	Neisseria
Species:	N. gonorrhoeae
Binomial name
Neisseria gonorrhoeae Zopf, 1885

Neisseria gonorrhoeae, also known as Gonococci (plural), or Gonococcus (singular), is a species of Gram-negative coffee bean-shaped diplococci bacteria responsible for the sexually transmitted disease gonorrhea.^[1]

N.gonorrhoeae was first described by Albert Neisser in 1879.

Microbiology

Neisseria are fastidious Gram-negative cocci, requiring nutrient supplementation to grow in laboratory cultures. Specifically, they grow on chocolate agar with carbon dioxide. These cocci are facultatively intracellular and typically appear in pairs (diplococci), in the shape of coffee beans. Of the eleven species of Neisseria that colonize humans, only two are pathogens. N. gonorrhoeae is the causative agent of gonorrhoea and is transmitted via sexual contact.^[2]

Neisseria is usually isolated on Thayer-Martin agar—an agar plate with three different antibiotics and nutrients which not only facilitate the growth of Neisseria species, but inhibit the growth of Gram-positive organisms and most bacilli and fungi. Further testing to differentiate the species includes testing for oxidase (all Neisseria show a positive reaction) and the carbohydrates maltose, sucrose, and glucose test in which N. gonorrhoeae will only oxidize (that is, utilize) the glucose.

N. gonorrhoeae are able to pull 100,000 times their own weight and it has been claimed that the pili used to do so are the strongest biological motor known to date, exterting one nanonewton.^[3]

Disease

Symptoms of infection with N. gonorrhoeae differ depending on the site of infection.

Infection of the genitals can result in a purulent (or pus-like) discharge from the genitals which may be foul smelling, inflammation, redness, swelling, dysuria and a burning sensation during urination.

N. gonorrhoeae can also cause conjunctivitis, pharyngitis, proctitis or urethritis, prostatitis and orchitis.

Conjunctivitis is common in neonates and silver nitrate or antibiotics are often applied to their eyes as a preventive measure against gonorrhoea. Neonatal gonorrheal conjunctivitis is contracted when the infant is exposed to N. gonorrhoeae in the birth canal, and can result in corneal scarring or perforation.

Disseminated N. gonorrhoeae infections can occur, resulting in endocarditis, meningitis or gonococcal dermatitis-arthritis syndrome. Dermatitis-arthritis syndrome presents with arthralgia, tenosynovitis and painless non-pruritic dermatitis.

Infection of the genitals in females with N. gonorrhoeae can result in pelvic inflammatory disease if left untreated, which can result in infertility. Pelvic inflammatory disease results if N. gonorrhoeae travels into the pelvic peritoneum (via the cervix, endometrium and fallopian tubes).

Treatment and Prevention

If N. gonorrhoeae is resistant to the penicillin family of antibiotics, then ceftriaxone (a third-generation cephalosporin) is often used. Sexual partners should also be notified and treated.

Patients should also be tested for other sexually transmitted infections, especially Chlamydia infections, since co-infection is frequent.

Transmission can be reduced by the usage of condoms during intercourse and oral sex and limiting sexual partners.

See also

• Neisseria meningitidis

References

External links

• Todar's Online Textbook of Bacteriology
• eMedicine: Gonococcal Infections