Mycoplasma genitalium belongs to the genus Mycoplasma. Mycoplasma was first isolated from sick cattle in 1898. With Mycoplasma pneumoniae, a form pathogenic for humans was detected for the first time in 1962. In 1981, Mycoplasma genitalium was discovered and in 1983 it was assigned to the genus Mycoplasma as a new species. Complete gene sequencing was published in 1995.
What is mycoplasma genitalium?
The bacterial species Mycoplasma genitalium belongs to the genus Mycoplasma and the superordinate class Mollicutes. Bacterial species in the class Mollicutes do not have a cell wall. The name Mollicutes means soft skin or soft-skinned (Molli= soft, plump; Cutis= skin) and indicates this. The lack of a cell wall in Mollicutes in general and Mycoplasmas in particular allows for a pleomorphic, or multiform, form. The bacteria appear both vesicular and filamentous and can change shape as needed. The filamentous shape of mycoplasmas is very reminiscent of a fungus, which is expressed in the name mycoplasma. Translated, mycoplasma (myco = fungus and plasma = shape) roughly means “mushroom-shaped.” However, the lack of a cell wall causes, in addition to the pleomorphic properties, pronounced susceptibilities to various environmental influences. Thus, even slight osmotic fluctuations of the surrounding medium can lead to the killing of the germs. On the other hand, due to the lack of a cell wall, mycoplasmas also exhibit a natural resistance to antibiotics that adhere to the cell wall. Conventional antibiotics such as penicillins thus show no effect. Mycoplasmas are very small in shape and, at 200-300 nanometers, are among the smallest bacterial genera in the world. Because of their small size, they often play a role as laboratory contaminants. Since most mass-produced sterile filters do not fall below the nominal pore size of 220 nanometers, effective filtration of mycoplasmas cannot be guaranteed. The genome of mycoplasmas is among the smallest prokaryotic genomes in the world. Thus, at 580-1,380 kbp, mycoplasmas are among the genetically smallest germs capable of autoreplication, along with the nanoarchaeum equitans (~500 kbp) and the endosymbiont Carsonella ruddii (about 160 kbp). Another striking feature is the cholesterol contained in the cell membrane of mycoplasmas, which is otherwise only found in eukaryotic cells. Precise RNA studies show that the genus Mollicutes cannot be counted among the base of the bacterial phylogenetic tree, but have arisen through degenerative evolution. A descent from germs of the Lactobacillus group and a subsequent loss of large parts of genetic information by degenerative evolution is very likely and makes the class of Mollicutes representatives of the living beings with the smallest known genome. The small genome of mycoplasmas lends itself to research into synthesis, and so it is not surprising that the research group led by Craig Venter synthesized the germ Mycoplasma genitalium in 2008. The replica is called Mycoplasma genitalium JCVI-1.0 and is considered the first bacterium to be completely synthesized.
Occurrence, distribution, and properties
Mycoplasmas have a parasitic lifestyle and are dependent on host cells. They can parasitize extracellularly on the host cell as well as intracellularly. Mycoplasmas depend on essential metabolic components such as amino and nucleic acids from the host cell. There is the ability to shrink the genome as needed, which accommodates an undemanding parasitic lifestyle. Mycoplasma genitalium colonizes the urethra, where it lives preferentially on epithelial cells.
Diseases and symptoms
Mycoplasmas are responsible for numerous diseases because of their parasitic lifestyle. Along with Chlamydia trachomatis, Mycoplasma genitalium is one of the most common pathogens for non-gonococcal urethritis. Non-gonococcal urethritis is the term used to describe urethritis that is not caused by the gonococci that are usually responsible. The urethritis usually runs with typical symptoms such as strong burning during urination and mucopurulent discharge. As a result, women may experience heavy bleeding after sexual intercourse. Women may also develop serious complications.Due to the much shorter urethra, severe secondary inflammation may occur. Inflammatory diseases such as cervicitis, endometritis, salpingitis and other pelvic inflammatory diseases may occur. A correlation with other ailments and diseases such as infertility or ovarian cancer has been statistically demonstrated, but has not been causally proven to date. Decreased prostate development has been observed in men with past infection and is under discussion. A higher intensity of HIV infections due to Mycoplasma genitalium is also discussed. Furthermore, it is questionable whether Mycoplasma genitalium needs to be defined as a sexually transmitted pathogen. Urethritis, popularly known as gonorrhea, is a commonly transmitted infectious disease. Treatment with antibiotics is possible. However, since several pathogens can cause the symptoms, identification of the antigen with all resistance is essential for successful antibiotic therapy. For Mycoplasma genitalium, as for most germs of the Mollicutes class, an antibiotic of the macrolide class is recommended, especially azithromycin. The macrolides do not attack the pathogen at the cell surface, as penicillin does, but prevent further replication by slowing the protein biosynthesis of the pathogen. Hasty antibiotic administration, especially of penicillin, can lead to increased persistence of the pathogen, especially with germs of the Mollicutes class.