World Library  
Flag as Inappropriate
Email this Article

Neisseria gonorrhoeae

Article Id: WHEBN0000061837
Reproduction Date:

Title: Neisseria gonorrhoeae  
Author: World Heritage Encyclopedia
Language: English
Subject: Gonorrhea, Pathogenic bacteria, List of infectious diseases, Conjunctivitis, Gram-negative bacteria
Publisher: World Heritage Encyclopedia

Neisseria gonorrhoeae

Neisseria gonorrhoeae
Neisseria gonorrhoeae cultured on two different media types and presented in stereoscopic 3d.
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Beta Proteobacteria
Order: Neisseriales
Family: Neisseriaceae
Genus: Neisseria
Species: N. gonorrhoeae
Binomial name
Neisseria gonorrhoeae
Zopf, 1885

Gonococcus Neisser 1879

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 infection gonorrhea.[1]

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


Neisseria are fastidious Gram-negative cocci that require nutrient supplementation to grow in laboratory cultures. To be specific, 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 gonorrhea (also called "The Clap," which is derived from the French word "clapier," meaning "brothel") and is transmitted via sexual contact.[2]

Neisseria is usually isolated on Thayer-Martin agar (or VPN agar)—an agar plate containing antibiotics (vancomycin, colistin, nystatin, and trimethoprim) and nutrients that facilitate the growth of Neisseria species while inhibiting the growth of contaminating bacteria and fungi. Further testing to differentiate the species includes testing for oxidase (all clinically relevant Neisseria show a positive reaction) and the carbohydrates maltose, sucrose, and glucose test in which N. gonorrhoeae will oxidize (that is, utilize) only the glucose.

N. gonorrhoeae are motile (twitching motility) and possess type IV pili to adhere to surfaces. The type IV pili operate mechanistically similar to a grappling hook. Pili extend and attach to a substrate that signals the pilus to retract, dragging the cell forward. 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, exerting one nanonewton.[3]

N. gonorrhoeae has surface proteins called Opa proteins, which bind to receptors on immune cells. In so doing, N.gonorrhoeae is able to prevent an immune response. The host is also unable to develop an immunological memory against N. gonorrhoeae – which means that future reinfection is possible. N. gonorrhoeae can also evade the immune system through a process called antigenic variation, in which the N. gonorrhoeae bacterium is able to alter the antigenic determinants (sites where antibodies bind) such as the Opa proteins[4] and Type IV pili[5] that adorn its surface. The many permutations of surface proteins make it more difficult for immune cells to recognize N. gonorrhoeae and mount a defense.[6]

The growth of Neisseria gonorrhoeae colonies on New York City medium agar, a specialised and selective media for Gonococci

N. gonorrhoeae is naturally competent for DNA transformation as well as being capable of conjugation. These processes allow for the DNA of N. gonorrhoeae to acquire or spread new genes. Especially dangerous from the aspect of healthcare is the ability to conjugate, since this can lead to antibiotic resistance.[7]

In 2011, researchers at Northwestern University found evidence of a human DNA fragment in a Neisseria gonorrhoeae genome, the first example of horizontal gene transfer from humans to a bacterial pathogen.[8][9]


N. gonorrhoeae is transmitted from person to person during sexual relations. Traditionally, the bacteria was thought to move attached to spermatozoon, but this hypothesis did not explain female to male transmission of the disease. A recent study suggests that rather than “surf” on wiggling sperm, N. gonorrhoeae bacteria uses hairlike structures called pili to anchor onto proteins in the sperm and move through coital liquid.[10]


Symptoms of infection with N. gonorrhoeae differ, depending on the site of infection. Note also that 10% of infected males and 80% of infected females are asymptomatic.

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

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

Conjunctivitis is common in neonates (newborns), 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 lead to corneal scarring or perforation, resulting in blindness in the neonate.

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 (non-itchy) 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). Infertility is caused by inflammation and scarring of the fallopian tube. Infertility is a risk to 10 to 20% of the females infected with N. gonorrhoeae.

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.[11]

Antibiotic-resistant gonorrhea has been noted by epidemiologists; beginning in the 1940s, gonorrhea was treated with penicillin, but doses had to be continually increased in order to remain effective, and, by the ’70s, penicillin- and tetracycline-resistant gonorrhea emerged in the Pacific Basin. These resistant strains then spread to Hawaii, California, the rest of the United States, and Europe. Fluoroquinolones were the next line of defense, but soon resistance to this antibiotic emerged as well. Since 2007, standard treatment has been third-generation cephalosporins, such as ceftriaxone, which are considered to be our “last line of defense.”[12]

Recently, a high-level ceftriaxone-resistant strain of gonorrhea, called H041, was discovered in Japan. Lab tests found it to be resistant to high concentrations of ceftriaxone, as well as most of the other antibiotics tested. Within N. gonorrhoeae, there are genes that confer resistance to every single antibiotic used to cure gonorrhea, but thus far they do not coexist within a single gonococcus. Because of N. gonorrhoeae’s high affinity for horizontal gene transfer, however, antibiotic-resistant gonorrhea is seen as an emerging public health threat.[12]

Patients should also be tested for other sexually transmitted infections (there is a fivefold increase of HIV transmission[13]), especially Chlamydia infections, since co-infection is frequent (up to 50% of cases). Antibacterial coverage is often included for Chlamydia because of this.

Transmission can be reduced by the usage of latex barriers, such as condoms or dental dams, during intercourse, oral and anal sex, and by limiting sexual partners.


Due to the relative frequency of infection and the emerging development of antibiotic resistance in strains of N. gonorrhoeae, vaccines are thought to be an important goal in the prevention of infection. However, there has been a relatively low emphasis on research to such a vaccine in the medical literature and few human clinical trials for prospective vaccines. The ability to develop an effective vaccine has been limited by the lack of acquired immunity to infection to model a vaccine after and the current lack of commitment in effort and resources.[14]

Survival of gonococci

The exudates from infected individuals contain many polymorphonuclear leukocytes (PMN) with ingested gonococci. These gonococci stimulate the PMN to release an internal oxidative burst involving reactive oxygen species in order to kill the gonococci.[15] However, a significant fraction of the gonococci can resist killing and are able to reproduce within the PMN phagosomes.

Stohl and Seifert showed that the bacterial RecA protein, that mediates recombinational repair of DNA damage, plays an important role in gonococcal survival.[16] The protection afforded by RecA protein may be linked to transformation, the process by which recipient gonococci take up DNA from neighboring gonococci and integrate this DNA into the recipient genome through recombination. Michod et al. have suggested that an important benefit of transformation in N. gonorrhoeae may be recombinational repair of oxidative DNA damages caused by oxidative attack by the hosts phagocytic cells.[17]

See also


  1. ^ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill.  
  2. ^ Genco, C; Wetzler, L (editors) (2010). Neisseria: Molecular Mechanisms of Pathogenesis. Caister Academic Press.  
  3. ^ "Mighty microbe pulls 100,000 times its bodyweight". New Scientist. 19 April 2008. Retrieved 2009-07-01. 
  4. ^ Stern, Anne; Brown, Nickel, Meyer (10 October 1986). "Opacity genes in Neisseria gonorrhoeae: Control of phase and antigenic variation". Cell 47 (1): 61.  
  5. ^ Cahoon, Laty; Seifert (4 August 2011). "Focusing homologous recombination: pilin antigenic variation in the pathogenic Neisseria". Mol. Microbiol. 81 (5): 1136–1143.  
  6. ^ STI Awareness: Gonorrhea. Planned Parenthood Advocates of Arizona. 11 April 2011. Retrieved 31 August 2011.
  7. ^ Competence for natural transformation in Neisseria gonorrhoeae: components of DNA binding and uptake linked to type IV pilus expression.
  8. ^ "Gonorrhea Acquires a Piece of Human DNA: First Evidence of Gene Transfer from Human Host to Bacterial Pathogen". 13 February 2011. Retrieved 15 February 2011. 
  9. ^ Anderson, Mark T.; H. Steven Seifert (15 Feb 2011). "Opportunity and Means: Horizontal Gene Transfer from the Human Host to a Bacterial Pathogen". MBio 2 (1): e00005–11.  
  10. ^ Anderson, Mark T. (2014). "Seminal Plasma Initiates a Neisseria gonorrhoeae Transmission State". mBio 5 (2): e01004-13.  
  11. ^ "UK doctors advised gonorrhoea has turned drug resistant". BBC News. 10 October 2011. 
  12. ^ a b STI Awareness: Antibiotic-Resistant Gonorrhea. Planned Parenthood Advocates of Arizona. 6 March 2012. Retrieved 6 March 2012.
  13. ^ Emergence of multi-drug resistant Neisseria gonorrhoeae – Threat of global rise in untreatable sexually transmitted infections
  14. ^ Zhu W, Chen CJ, Thomas CE, Anderson JE, Jerse AE, Sparling PF (2011). "Vaccines for gonorrhea: can we rise to the challenge?". Front Microbiol 2: 124.  
  15. ^ Simons MP, Nauseef WM, Apicella MA (2005). Interactions of Neisseria gonorrhoeae with adherent polymorphonuclear leukocytes. Infect Immun 73(4):1971-1977. PMID 1578453
  16. ^ Stohl EA, Seifert HS (2006). Neisseria gonorrhoeae DNA recombination and repair enzymes protect against oxidative damage caused by hydrogen peroxide. J Bacteriol 188(21):7645-7651. PMID 16936020
  17. ^ Michod RE, Bernstein H, Nedelcu AM (2008). Adaptive value of sex in microbial pathogens. Infect Genet Evol 8(3):267-285. Review. doi:10.1016/j.meegid.2008.01.002 PMID 18295550

External links

  • Todar's Online Textbook of Bacteriology
  • eMedicine: Gonococcal Infections
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.