Neisseria gonorrhoeae is a gram negative diplococcic bacteria it is often called Gonococcus. The disease caused by Neisseria gonorrhoeae is called Gonorrhoea and it is a venereal disease.
Table of Contents
- Neisseria gonorrhoeae Diseases (Neisseria gonorrhoeae Infections)
- Neisseria gonorrhoeae Epidemiology
- Neisseria gonorrhoeae Transmission
- Neisseria gonorrhoeae Characteristics and Morphology (Structure)
- Neisseria gonorrhoeae Virulence Factors
- Neisseria gonorrhoeae Pathogenesis
- Neisseria gonorrhoeae Symptoms and Signs
- Neisseria gonorrhoeae Diagnosis
- Neisseria gonorrhoeae Culture
- Neisseria gonorrhoeae Treatment
- Neisseria gonorrhoeae Complications
- Neisseria gonorrhoeae Prevention
Neisseria gonorrhoeae Diseases (Neisseria gonorrhoeae Infections)
- Purulent conjunctivitis
- Arthritis (when dissemination occurs)
- Endocarditis (in disseminated cases)
Neisseria gonorrhoeae Epidemiology
Neisseria gonorrhoeae infection (Gonorrhea) occurs worldwide and it is one of the most common causes of female infertility; the infection occurs only in humans. It has an annual incidence of 12 cases per 1,000 inhabitants in developed countries of the world. Because of AIDS prophylaxis, there has been a reduction in the incidence of Neisseria gonorrhoeae infection in recent years.
Neisseria gonorrhoeae Transmission
Transmission of Neisseria gonorrhoeae occurs mainly through sexual intercourse and that is why it is called a venereal disease. Other means of transmission include during childbirth (vertical transmission) where the baby gets infected through the birth canal. It has an incubation period of 2-14 days with most symptoms occurring between days 2 and 5.
Neisseria gonorrhoeae Characteristics and Morphology (Structure)
- Neisseria gonorrhoeae shape looks like coffee bean
- Neisseria gonorrhoeae are cocci (round shape) that are usually paired (hence they are called Diploccoci)
- Neisseria gonorrhoeae measures about 1 micrometer in diameter
- The presence of pili helps in attaching to mucosal cells of the host
Neisseria gonorrhoeae Virulence Factors
- The Opa protein on the surface membrane and outer membrane has attachment pili that aids in adhesion to cells of the urogenital tract
- The Opa protein also helps to direct the invasion process by means of endocytosis.
- The outer membrane porin Por of Neisseria gonorrhoeae prevents the fusion of phagosome and lysosomes and therefore helps to avoid attack by the immune system.
- The Lipo-Oligosaccharide (LOS) that is located in the outer membrane of Neisseria gonorrhoeae is responsible for resistance to complement system (serum resistance) and also helps against inflammatory tissue reaction in a similar manner as that of the more complex structured LPS of enterobacteria.
- Neisseria gonorrhoeae has the ability to trap and store iron from lactoferrin and transferrin proteins and use the iron for growth
- Neisseria gonorrhoeae produces an enzyme (protease) against immunoglobulin A1 (IgA1) that hydrolyzes secretory antibodies in the mucosal secretions and therefore evade destruction by secretory antibodies
- Neisseria gonorrhoeae has high antigen variability as a result of the attachment pili and the Opa protein this makes it possible for repeated infections because the body has to keep producing different antibodies for each new infection.
Neisseria gonorrhoeae Pathogenesis
Gonorrhea is a disease that is transmitted through sexual intercourse from an infected partner (venereal disease) . Neisseria gonorrhoeae penetrate into the urogenital mucosa and cause local purulent infection this infection in men could affect the prostate and epididymis causing Prostatitis and Epididymitis respectively while Neisseria gonorrhoeae infection in women can cause salpingitis, oophoritis or even peritonitis. When gonococci reach the conjunctival membrane of the eyes, they may cause purulent conjunctivitis which is mostly seen in newborn children.
Neisseria gonorrhoeae infection may also affect the rectal or pharyngeal mucosa; if hematogenous spread occurs, dissemination may lead to arthritis or even endocarditis.
Neisseria gonorrhoeae Symptoms and Signs
- Some infections may not show symptoms or signs (asymptomatic)
- Painful urination in men
- Discharge from the penis in Men
- In homosexual men, rectal infection due to Neisseria gonorrhoeae may produce proctitis with pain, discharge and itch
- Gonorrhea symptoms in Women includes increased or altered vaginal discharge, pelvic pain due to ascending infection and intermenstrual bleeding
- In women, there may be painful sexual intercourse( dyspareunia)
- May progress to cause Pelvic inflammatory disease (PID)
Neisseria gonorrhoeae Diagnosis
- Gram stain using methylene blue
- Immunofluorescence or Coagglutination methods
- Direct detection using enzymatic immunosorbence test
- Use of Gene probe to identify gonococcus specific DNA sequences coding for rRNA
Neisseria gonorrhoeae Culture
Neisseria gonorrhoeae can be grown on moist culture mediums that are enriched with protein such as blood in an atmosphere having about 5 to 10% of carbon dioxide (CO2) . Gonococci are sensitive in cultures, hence the material must be used immediately after they are obtained to inoculate the Thayer-Martin blood agar and antibiotics should be added to eliminate accompanying flora – culture should grow oxidase positive colonies that are non-maltose fermenting and not encapsulated. The identification of Neisseria gonorrhoeae involves both morphology and biochemical characteristics.
Neisseria gonorrhoeae Treatment
The drug of choice now used for treatment of Neisseria gonorrhoeae infctions is third-generation Cephalosporins such as Ceftriaxone. Penicillin G was initially used but now has growing resistance because of new strains having enzymes that neutralize penicillin known as Penicillinase. Other drugs use in treating gonoccocal infection are fluorinated 4-quinolones such as Ciprofloxacin or Ofloxacin.
Neisseria gonorrhoeae Complications
- Ophthalmia neonatorum
- Gonorrhea may give rise to ascending infections involving the epididymis or prostate
- Formation of Bartholin’s abscesses
- Peri-hepatitis (Fitzhugh-Curtis syndrome) this occurs in rare cases
- Formation of urethral strictures
- Ectopic pregnancy
Neisseria gonorrhoeae Prevention
- Stopping the spread of gonorrhea involves prompt diagnosis and treatment
- 100% prevention of ophthalmia neonatorum caused by Neisseria gonorrhoeae is possible using a single parenteral dose of 125mg ceftriaxone
- Local prophylaxis can also help to prevent ophthalmia neonatarum and this is done using a 1% solution of silver nitrate or eye ointments containing 1% tetracycline or 0.5% erythromycin.