Neisseria gonorrhoeae
Encyclopedia
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
.
N. gonorrhoea was first described by Albert Neisser
in 1879.
are fastidious Gram-negative cocci that require 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 gonorrhea
(also called "The Clap," which is derived from the French word "clapier," meaning "brothel") and is transmitted via sexual contact.
Neisseria is usually isolated on Thayer-Martin agar
—an agar plate
containing antibiotic
s (Vancomycin
, Colistin
, Nystatin
, and SXT
) 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 only oxidize (that is, utilize) 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
which 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.
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 Opa proteins 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.
N. gonorrhoeae is naturally competent for DNA transformation as well as being capable of conjugation. Both of these concepts allow for the DNA of N. gonorrhoeae the ability to undergo conformational changes. Especially dangerous to the health industry is the ability to conjugate since this can lead to antibiotic resistance.
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.
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.
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 (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.
Gram-negative
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
coffee bean
Coffee bean
A coffee bean is a seed of a coffee plant. It is the pit inside the red or purple fruit often referred to as a cherry. Even though they are seeds, they are referred to as 'beans' because of their resemblance to true beans. The fruits - coffee cherries or coffee berries - most commonly contain two...
-shaped diplococci bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
responsible for the sexually transmitted infection gonorrhea
Gonorrhea
Gonorrhea is a common sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae. The usual symptoms in men are burning with urination and penile discharge. Women, on the other hand, are asymptomatic half the time or have vaginal discharge and pelvic pain...
.
N. gonorrhoea was first described by Albert Neisser
Albert Ludwig Sigesmund Neisser
Albert Ludwig Sigesmund Neisser was a German physician who discovered the causative agent of gonorrhea, a strain of bacteria that was named in his honour ....
in 1879.
Microbiology
NeisseriaNeisseria
The Neisseria is a large genus of commensal bacteria that colonize the mucosal surfaces of many animals. Of the 11 species that colonize humans, only two are pathogens. N. meningitidis and N. gonorrhoeae often cause asymptomatic infections, a commensal-like behavior...
are fastidious Gram-negative cocci that require nutrient supplementation to grow in laboratory cultures. Specifically, they grow on chocolate agar
Chocolate agar
Chocolate agar - is a non-selective, enriched growth medium. It is a variant of the blood agar plate. It contains red blood cells, which have been lysed by heating very slowly to 56 °C. Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae...
with carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
. 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
Gonorrhea
Gonorrhea is a common sexually transmitted infection caused by the bacterium Neisseria gonorrhoeae. The usual symptoms in men are burning with urination and penile discharge. Women, on the other hand, are asymptomatic half the time or have vaginal discharge and pelvic pain...
(also called "The Clap," which is derived from the French word "clapier," meaning "brothel") and is transmitted via sexual contact.
Neisseria is usually isolated on Thayer-Martin agar
Thayer-Martin agar
Thayer-Martin agar is a Mueller-Hinton agar with 5% chocolate sheep blood and antibiotics. It is used for culturing and primarily isolating pathogenic Neisseria bacteria, including Neisseria gonorrhoeae and Neisseria meningitidis, as the medium inhibits the growth of most other microorganisms...
—an agar plate
Agar plate
An agar plate is a Petri dish that contains a growth medium used to culture microorganisms or small plants like the moss Physcomitrella patens.Selective growth compounds may also be added to the media, such as antibiotics....
containing antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s (Vancomycin
Vancomycin
Vancomycin INN is a glycopeptide antibiotic used in the prophylaxis and treatment of infections caused by Gram-positive bacteria. It has traditionally been reserved as a drug of "last resort", used only after treatment with other antibiotics had failed, although the emergence of...
, Colistin
Colistin
Colistin is a polymyxin antibiotic produced by certain strains of Bacillus polymyxa var. colistinus. Colistin is a mixture of cyclic polypeptides colistin A and B. Colistin is effective against most Gram-negative bacilli and is used as a lingerdoodle. It is one of the last-resort antibiotics for...
, Nystatin
Nystatin
Nystatin is a polyene antifungal medication to which many molds and yeast infections are sensitive, including Candida. Due to its toxicity profile, there are currently no injectable formulations of this drug on the US market...
, and SXT
Co-trimoxazole
Trimethoprim/sulfamethoxazole or co-trimoxazole is a sulfonamide antibiotic combination of trimethoprim and sulfamethoxazole, in the ratio of 1 to 5, used in the treatment of a variety of bacterial infections.The name co-trimoxazole is the British Approved Name, and has been marketed worldwide...
) 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
Oxidase
An oxidase is any enzyme that catalyzes an oxidation-reduction reaction involving molecular oxygen as the electron acceptor. In these reactions, oxygen is reduced to water or hydrogen peroxide ....
(all clinically relevant Neisseria show a positive reaction) and the carbohydrates maltose
Maltose
Maltose , or malt sugar, is a disaccharide formed from two units of glucose joined with an αbond, formed from a condensation reaction. The isomer "isomaltose" has two glucose molecules linked through an α bond. Maltose is the second member of an important biochemical series of glucose chains....
, sucrose
Sucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...
, and glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
test in which N. gonorrhoeae will only oxidize (that is, utilize) 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
Grappling hook
A grappling hook is an anchor with multiple hooks , attached to a rope; it is thrown, dropped, sunk, projected, or fastened directly by hand to where at least one hook may catch and hold. Generally, grappling hooks are used to temporarily secure one end of a rope. They may also be used to dredge...
. Pili extend and attach to a substrate
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
which 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.
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
Antigenic variation
Antigenic variation refers to the mechanism by which an infectious organism such as a protozoan, bacterium or virus alters its surface proteins in order to evade a host immune response. Immune evasion is particularly important for organisms that target long-lived hosts, repeatedly infect a single...
, in which the N. gonorrhoeae bacterium is able to alter the Opa proteins 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.
N. gonorrhoeae is naturally competent for DNA transformation as well as being capable of conjugation. Both of these concepts allow for the DNA of N. gonorrhoeae the ability to undergo conformational changes. Especially dangerous to the health industry is the ability to conjugate since this can lead to antibiotic resistance.
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
Horizontal gene transfer
Horizontal gene transfer , also lateral gene transfer , is any process in which an organism incorporates genetic material from another organism without being the offspring of that organism...
from humans to a bacterial pathogen.
Disease
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
Pus
Pus is a viscous exudate, typically whitish-yellow, yellow, or yellow-brown, formed at the site of inflammatory during infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection of pus within or beneath the epidermis is known as a pustule or...
-like) discharge from the genitals which may be foul smelling. Symptoms may include inflammation, redness, swelling, and dysuria
Dysuria
In medicine, specifically urology, dysuria refers to painful urination.Difficult urination is also sometimes described as dysuria.It is one of a constellation of irritative bladder symptoms, which includes urinary frequency and haematuria....
N. gonorrhoeae can also cause conjunctivitis
Conjunctivitis
Conjunctivitis refers to inflammation of the conjunctiva...
, pharyngitis
Pharyngitis
Pharyngitis is an inflammation of the throat or pharynx. In most cases it is quite painful, and is the most common cause of a sore throat.Like many types of inflammation, pharyngitis can be acute – characterized by a rapid onset and typically a relatively short course – or chronic....
, proctitis
Proctitis
Proctitis is an inflammation of the anus and the lining of the rectum, affecting only the last 6 inches of the rectum.-Overview:Symptoms are ineffectual straining to empty the bowels, diarrhea, rectal bleeding and possible discharge, a feeling of not having adequately emptied the bowels,...
or urethritis
Urethritis
Urethritis is inflammation of the urethra. The most common symptom is painful or difficult urination.-Causes:The disease is classified as either gonococcal urethritis, caused by Neisseria gonorrhoeae, or non-gonococcal urethritis , most commonly caused by Chlamydia trachomatis...
, prostatitis
Prostatitis
Prostatitis is an inflammation of the prostate gland, in men. A prostatitis diagnosis is assigned at 8% of all urologist and 1% of all primary care physician visits in the United States.-Classification:...
and orchitis
Orchitis
Orchitis or orchiditis is a condition of the testes involving inflammation. It can also involve swelling and frequent infection.-Symptoms:Symptoms of orchitis are similar to those of testicular torsion...
.
Conjunctivitis is common in neonates (newborns), and silver nitrate
Silver nitrate
Silver nitrate is an inorganic compound with chemical formula . This compound is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides...
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
Endocarditis
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves . Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or even on intracardiac devices...
, meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
or gonococcal dermatitis-arthritis syndrome. Dermatitis-arthritis syndrome presents with arthralgia
Arthralgia
Arthralgia literally means joint pain; it is a symptom of injury, infection, illnesses or an allergic reaction to medication....
, tenosynovitis
Tenosynovitis
Tenosynovitis is the inflammation of the fluid-filled sheath that surrounds a tendon. Symptoms of tenosynovitis include pain, swelling and difficulty moving the particular joint where the inflammation occurs. When the condition causes the finger to "stick" in a flexed position, this is called...
and painless non-pruritic (non-itchy) dermatitis
Dermatitis
-Etymology:Dermatitis derives from Greek derma "skin" + -itis "inflammation" and genetic disorder.-Terminology:There are several different types of dermatitis. The different kinds usually have in common an allergic reaction to specific allergens. The term may describe eczema, which is also called...
.
Infection of the genitals in females with N. gonorrhoeae can result in pelvic inflammatory disease
Pelvic inflammatory disease
Pelvic inflammatory disease is a generic term for inflammation of the uterus, fallopian tubes, and/or ovaries as it progresses to scar formation with adhesions to nearby tissues and organs. This may lead to infections. PID is a vague term and can refer to viral, fungal, parasitic, though most...
if left untreated, which can result in infertility. Pelvic inflammatory disease
Pelvic inflammatory disease
Pelvic inflammatory disease is a generic term for inflammation of the uterus, fallopian tubes, and/or ovaries as it progresses to scar formation with adhesions to nearby tissues and organs. This may lead to infections. PID is a vague term and can refer to viral, fungal, parasitic, though most...
results if N. gonorrhoeae travels into the pelvic peritoneum
Peritoneum
The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal organs — in amniotes and some invertebrates...
(via the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
, endometrium
Endometrium
-Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
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 resistantAntibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...
to the penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....
family of antibiotics, then ceftriaxone
Ceftriaxone
Ceftriaxone is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram-positive and Gram-negative bacteria. In most cases, it is considered to be equivalent to cefotaxime in terms of safety and efficacy...
(a third-generation cephalosporin
Cephalosporin
The cephalosporins are a class of β-lactam antibiotics originally derived from Acremonium, which was previously known as "Cephalosporium".Together with cephamycins they constitute a subgroup of β-lactam antibiotics called cephems.-Medical use:...
) 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 (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.