Neisseria gonorrhoeae characteristics, morphology, habitat

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Sherman Hoover

Neisseria gonorrhoeae It is the bacterial agent that causes gonorrhea, also known as gonorrhea. This microorganism is circular in shape and lacks motility.

As its cell wall is thin and rich in different types of lipids, it is considered a gram negative bacterium.. N. gonorrhoeae is a unique human pathogen and usually inhabits the urogenital tract.

The infection develops in both men and women. In the female genitalia, the infection is restricted to the cervix and can cause inflammation in the pelvis. In men it attacks the urethra and the symptoms are epididymitis in the testicles. In both sexes this disease can lead to sterility.

Its diagnosis can be carried out by means of DNA tests or by culture tests. The latter are usually quite useful, since susceptibility tests can be performed to different antibiotics..

This venereal disease affects a considerable number of people annually. According to population studies conducted in Europe and the United States, gonorrhea is the second most common sexually transmitted disease.

Regarding its distribution, gonorrhea has been reported worldwide. This disease is widely spread in all social strata, being higher in low socioeconomic levels.

Article index

  • 1 Features
  • 2 Morphology
  • 3 Habitat
  • 4 Culture and identification
  • 5 Symptoms and treatment
  • 6 References

Characteristics

Family bacteria Neisseriaceae they are characterized by being aerobic or facultative anaerobic. They are heterotrophic, this term indicates that they do not have the ability to produce their own food and use carbohydrates as a food source. In addition, these microorganisms do not have the ability to move..

Within the genre Neisseria, various human pathogens are found. N. gonorrhoeae is the causal agent of the gonorrah and N. meningitidis causes meningitis.

Similarly, there are certain species, such as N. sicca, N. mucosa Y N lactamic, that are not harmful and are normal inhabitants of human flora, including the mouth.

The optimum growth temperature of N. gonorrhoeae is 36 to 39 ° C.

Morphology

N. gonorrhoeae It is a bacterium with a circular shape and thanks to this characteristic they are attributed the name of gonococci. They do not have a capsule and are not spore-forming. The average size is 0.8 µm and the range ranges from 0.6 to 1 µm.

Under the microscope, the shape is similar to that of a kidney or a bean and is found within cells, specifically within polymorphonuclear leukocytes.

These organisms are usually found in pairs with adjacent concave sides and are called diplococci. However, young colonies can be grouped into groups of four, known as tetrads. Occasionally they can be found as short chains.

Phenotypically, it is a gram negative bacterium. However, the outer membrane contains lipooligosaccharides and not lipopolysaccharides, as usual. The Gram stain, together with its diplococcal morphology, are quite useful characteristics for its identification..

The cell surface has a series of pilis, also called fimbriae. These projections or appendages are similar to a hair. They are composed of polymers and structural proteins.

One of these proteins, adhesin, is responsible for adhering to the pathogen on the surface of the epithelial mucosa and allows bacterial colonization.

Habitat

Neisseria gonorrhoeae it is a pathogenic bacterium exclusive to humans. The presence of this harmful microorganism is due, in most cases, to sexual contact.

Non-sexual transmission is rare but can occur. They include bacterial transmission during childbirth, by the contact of the newborn's eyes with the mother's vagina (neonatal ophthalmia).

The frequent habitat of this microorganism is the human urogenital tract. In women they are commonly found in the endocervix and in men in the urethra.

To a lesser extent, this pathogen can be found in the eyes, oral, nasopharyngeal and anal cavities. In healthy individuals it is not common to find them. That is, it is not part of normal human flora.

Culture and identification

Bacteria cultures Neisseria gonorrhoeae they are not simple. They require strict nutritional conditions and growth is slow.

They are generally grown on a rich medium, on blood agar or chocolate agar. Chocolate agar is blood heated to approximately 80 ° C and is used for the growth of fastidious bacteria. They are incubated at a temperature of 35 ° C with an atmosphere of COtwo, 5 to 10% carbon dioxide.

When the incubation period is prolonged, the colonies increase in size and take on a dull appearance. They can be stained with different techniques, including fluorescent antibodies.

Metabolically, in this bacterium the formation of lactic acid occurs through glycolysis. This process occurs by the combination of two metabolic pathways: Entner-Doudoroff and pentose phosphate, generating acetic acid carbon dioxide as end products.

For identification, acid production is measured from glucose and not from maltose, mannose, lactose, fructose, or sucrose. This biochemical test is called the "cystine trypticase agar test.".

In some cases the identification by oxidation of the sugars mentioned is complicated. Therefore, an optimized version includes enzyme tests.

They can also be identified by positive reaction to catalase and oxidase tests..

Symptoms and Treatment

Symptoms vary widely from patient to patient. Arthritis-dermatitis syndrome is a classic within the picture of this disease.

In early stages of infection, tendon and joint pain is common. Skin lesions include maculopapules and pustules, usually with hemorrhagic components.

Likewise, pharyngitis, urethritis, conjunctivitis and infections in the anus and rectum can occur in patients contaminated with this bacteria. The infection may also have no symptoms, particularly in women.

Gonorrhea is often treated with a single dose of antibiotics or a combination thereof. The most suggested in the literature are ceftriaxone, ciprofloxacin, doxycycline, gentamicin, gemifloxacin and azithromycin..

Like all bacterial diseases, treatment is complicated by the increased frequency of bacteria resistant to different antibiotics..

References

  1. Berenguer, J., & Sanz, J. L. (2004). Questions in microbiology. Editorial Helix.
  2. Forbes, B. A. (2009). Microbiological diagnosis. Panamerican Medical Ed..
  3. Lydyard, P., Cole, M., Holton, J., Irving, W., Venkatesan, P., Ward, K., & Porakishvili, N. (2009). Case studies in infectious disease. Garland science.
  4. MacFaddin, J. F. (2003). Biochemical tests for the identification of bacteria of clinical importance. Panamerican Medical Ed..
  5. Negroni, M. (2000). Stomatological microbiology. Panamerican Medical Ed..
  6. Pardi, G., Pérez, M. F., Pacheco, A., & Mata de Henning, M. (2004). Some considerations about Neisseria gonorrhoeae. Venezuelan Dental Act, 42(2), 122-127.
  7. Samaranayake, L. (2011). Essential Microbiology for Dentistry E-Book. Elsevier Health Sciences.
  8. Unemo, M., Savicheva, A., Budilovskaya, O., Sokolovsky, E., Larsson, M., & Domeika, M. (2006). Laboratory diagnosis of Neisseria gonorrhoeae in St Petersburg, Russia: inventory, performance characteristics and recommended optimizations. Sexually transmitted infections, 82(1), 41-44.
  9. Urbina, M. T., & Biber, J. L. (2009). Fertility and assisted reproduction. Panamerican Medical Ed..

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