Mycoplasma is a genus of bacteria that lack a cell wall around their cell membranes, making them naturally resistant to antibiotics that target cell wall synthesis.
Over 100 species have been included in the genus Mycoplasma.
Mycoplasma can be parasitic or saprotrophic.
Pathogenic Mycoplasma in humans, including M. pneumoniae, which is an important cause of walking pneumonia and other respiratory disorders, and M. genitalium, which is believed to be involved in pelvic inflammatory diseases.
They are the smallest bacterial cells yet discovered.
Mycoplasma cells are physically small, less than 1 µm.
They can survive without oxygen.
Mycoplasma come in various shapes: flask-shaped and elongated.
Due to the lack of a rigid cell wall, Mycoplasma can contort into a broad range of shapes, from round to oblong, and cannot be classified as rods, cocci or spirochetes.
Hundreds of mycoplasma species infect animals, and many species of Mycoplasma use humans as the primary host:
Mycoplasma species have been isolated from women with bacterial vaginosis, and pelvic inflammatory disease, and Mycoplasma genitalium has developed resistance to some antibiotics.
Mycoplasma infection is associated with increased risk of cervicitis, infertility, preterm birth and spontaneous abortion.
Mycoplasmas are associated with: infant respiratory distress syndrome, bronchopulmonary dysplasia, and intraventricular hemorrhage in preterm infants.
Mycoplasma are parasites or commensals of humans, animals, and plants.
The genus Mycoplasma uses vertebrate and arthropod hosts.
Mycoplasmal bacteria are also known as mollicutes.
The cell wall is absent and the plasma membrane forms the outer boundary of the cell.
Mycoplasma’s absence of cell wall allows these organisms to change their shape and are pleomorphic.
They lack a nucleus and other membrane-bound organelles.
Genetic material is a single DNA duplex.
Mycoplasma’s ribosomes are 70S type.
Some mycoplasma live as saprophytes but the majority are parasites of plants and animals, as mycoplasmal bacteria are unable to synthesise the required growth factor.
Mycoplasma species are often found in research laboratories as contaminants in cell culture.
They may induce changes in the cell, including chromosome aberrations, changes in metabolism and cell growth.
Mycoplasma detection techniques include: DNA probes, enzyme immunoassays, PCR, plating on sensitive agar and staining with a DNA stain.
P1 membrane associated antigen protein is the mycoplasma virulence factor.
The P1 membrane associated protein
allows adhesion to epithelial cells.
A P1 receptor is also expressed on erythrocytes which can lead to autoantibody agglutination from mycobacteria infection.
Several Mycoplasma species can cause disease.
M. pneumoniae, is an important cause of atypical pneumonia.
M. genitalium, is associated with pelvic inflammatory diseases.
Mycoplasma infections are associated with skin eruptions in 17% of cases.
Some Mycoplasma species are spread through sexual contact, and
some have a negative effect on fertility.
M. hominis can causes male sterility by genital inflammation.
Low birth-weight, preterm infants are susceptible to Mycoplasma infections.
Several species of Mycoplasma are frequently detected in different cancer cells.
These mycoplasmae have shown a strong correlation to malignant transformation in mammalian cells in vitro.
Cells that are chronically infected with the mycoplasma bacteria go through a multistep transformation, becoming hyperchromatic due to an increase of DNA in the nucleus of the cells.
Subsequently, the cells lose the need for a solid support to grow and proliferate.
Chronically infected cells with Mycoplasma for an extended period of time show significant chromosomal abnormalities: addition of chromosomes, the loss of entire chromosomes, partial loss of chromosomes, and chromosomal translocation.
Genetic abnormalities may contribute to the process of malignant transformation.
Chromosomal translocations and extra chromosomes create abnormally high activity of certain proto-oncogenes: encoding c-myc, HRAS, and vav.
Proto-oncogenes affect tumor suppressor genes are affected by the chromosomal changes induced by mycoplasma.
Gene activities markedly decreased during chronic infections with mycoplasma are the Rb and the p53 tumor suppressor genes.
Mycoplasmas do not cause the cellular changes by insertion of their own genetic material into the host cell.
The malignant transformation induced by mycoplasmae is is reversible early in the process.
Studies suggest infection and inflammation initiate certain cancers, including those of the prostate.
M. genitalium and M. hyorhinis induce malignant phenotype in benign human prostate cells.
Other types of cancer possibly associated with Mycoplasma include: Colon cancer, gastric cancer, lung and renal cancer.
Mycoplasma genitalium is a recently described sexually transmitted infection.
Mycoplasma genitalium infects the urogenital tract in men and women, with 7.9% of women and 8.8% of men being asymptomatic.
About 30 to 40% of men with persistent and recurrent urethritis are infected with M. genitalium.
Symptoms include dysuria, penile irritation, and urethral discomfort.
M genitalium has been linked to cervicitis, pelvic inflammatory disease and infertility in women.
Symptoms in women include cervicitis, postcoital bleeding, and painful intermenstrual bleeding and lower abdominal pain.
Treatment guidelines suggest sequential treatment with doxycycline followed by moxifloxacin.