''Mycoplasma'' is a genus of
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
that, like the other members of the class ''
Mollicutes
Mollicutes is a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin ''mollis'' (meaning "soft" or "pliable"), and ''cutis'' (meaning "skin"). Individuals are very small, typically only 0. ...
'', lack a
cell wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...
around their
cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
s.
Peptidoglycan
Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ...
(
murein
Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ba ...
) is absent. This characteristic makes them naturally resistant to antibiotics that target cell wall synthesis (like the
beta-lactam antibiotics
β-lactam antibiotics (beta-lactam antibiotics) are antibiotics that contain a beta-lactam ring in their chemical
structure. This includes penicillin derivatives (penams), cephalosporins and cephamycins (cephems), monobactams, carbapenems and ...
). They can be
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...
or
saprotrophic
Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi (f ...
. Several species are
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
ic 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. ''Mycoplasma'' species (like the other species of the class ''Mollicutes'') are among the smallest organisms yet discovered, can survive without oxygen, and come in various shapes. For example, ''M. genitalium'' is flask-shaped (about 300 x 600
nm), while ''M. pneumoniae'' is more elongated (about 100 x 1000
nm), many ''Mycoplasma'' species are
coccoid. Hundreds of ''Mycoplasma'' species infect animals.
The trivial name “mycoplasma” (plural mycoplasmas or mycoplasms) is commonly used for all members of the class ''Mollicutes''. In scientific classification, the designation ''Mycoplasma'' refers exclusively to the genus, a member of the ''
Mycoplasmataceae
Mycoplasmataceae is a family of bacteria in the order Mycoplasmatales. This family consists of the genera ''Mycoplasma'' and ''Ureaplasma''.
In 1967, the order Mycoplasmatales was incorporated into the class Mollicutes. Many species are sexuall ...
'', the only family of the order ''
Mycoplasmatales
Mycoplasmataceae is a family of bacteria in the order Mycoplasmatales. This family consists of the genera ''Mycoplasma'' and ''Ureaplasma''.
In 1967, the order Mycoplasmatales was incorporated into the class Mollicutes. Many species are sexuall ...
'' (see “scientific classification”).
Etymology
The term "mycoplasma", from the Greek μύκης, ' (fungus) and πλάσμα, ' (formed), was first used by
Albert Bernhard Frank
Albert Bernhard Frank (January 17, 1839 – September 27, 1900) was a German botanist, plant pathologist, and mycologist, born in Dresden. He is credited with coining the term ''mycorrhiza'' in his 1885 paper "Über die auf Wurzelsymbiose beruhen ...
in 1889 to describe an altered state of plant cell cytoplasm resulting from infiltration by fungus-like microorganisms.
Julian Nowak
Julian Ignacy Nowak (; 10 March 1865 – 7 November 1946) was a Polish microbiologist and politician who served as 9th Prime Minister of Poland in 1922.
Nowak studied medicine at the Jagiellonian University in 1886–1893 and was a professor th ...
later proposed the name mycoplasma for certain filamentous microorganisms imagined to have both cellular and acellular stages in their lifecycles, which could explain how they were visible with a microscope, but passed through filters impermeable to other bacteria.
Later, the name for these mycoplasmas was pleuropneumonia-like organisms (PPLO), broadly referring to organisms similar in
colonial morphology
In microbiology, colonial morphology refers to the visual appearance of bacterial colony, bacterial or fungus, fungal colonies on an agar plate. Examining colonial morphology is the first step in the identification of an unknown microbe. The syste ...
and filterability to the causative agent (a ''Mycoplasma'' species) of
contagious bovine pleuropneumonia
Contagious bovine pleuropneumonia (CBPP – also known as lung plague), is a contagious bacterial disease that afflicts the lungs of cattle, buffalo, zebu, and yaks.
It is caused by the bacterium ''Mycoplasma mycoides'', and the symptoms are pneu ...
.
At present, all these organisms are classified as ''Mollicutes'' and the term ''Mycoplasma'' refers solely to the genus.
Species that infect humans
Species of ''Mycoplasma'', other than those listed below, have been recovered from humans, but are assumed to have been contracted from a non-human host. The following species use humans as the primary host:
* ''
M. amphoriforme''
* ''
M. buccale''
* ''
M. faucium''
* ''
M. fermentans''
* ''
M. genitalium''
* ''
M. hominis''
* ''
M. incognitus''
* ''
M. lipophilum''
* ''
M. orale''
* ''
M. penetrans''
* ''
M. pirum''
* ''
M. pneumoniae''
* ''
M. primatum''
* ''
M. salivarium''
* ''
M. spermatophilum''
Pathophysiology
''Mycoplasma'' species have been isolated from women with
bacterial vaginosis
Bacterial vaginosis (BV) is a disease of the vagina caused by excessive growth of bacteria. Common symptoms include increased vaginal discharge that often smells like fish. The discharge is usually white or gray in color. Burning with urination ...
.
''M. genitalium'' is found in women with
pelvic inflammatory disease
Pelvic inflammatory disease, also known as pelvic inflammatory disorder (PID), is an infection of the upper part of the female reproductive system, namely the uterus, fallopian tubes, and ovaries, and inside of the pelvis. Often, there may be no ...
. In addition, infection is associated with increased risk of
cervicitis
Cervicitis is inflammation of the uterine cervix. Cervicitis in women has many features in common with urethritis in men and many cases are caused by sexually transmitted infections. Non-infectious causes of cervicitis can include intrauterine d ...
,
infertility
Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...
,
preterm birth
Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks Gestational age (obstetrics), gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 we ...
and
spontaneous abortion
Miscarriage, also known in medical terms as a spontaneous abortion and pregnancy loss, is the death of an embryo or fetus before it is able to survive independently. Miscarriage before 6 weeks of gestation is defined by ESHRE as biochemical lo ...
.
''Mycoplasma genitalium'' has developed resistance to some antibiotics. ''Mycoplasma'' species are associated with
infant respiratory distress syndrome
Infantile respiratory distress syndrome (IRDS), also called respiratory distress syndrome of newborn, or increasingly surfactant deficiency disorder (SDD), and previously called hyaline membrane disease (HMD), is a syndrome in premature infants c ...
,
bronchopulmonary dysplasia
Bronchopulmonary dysplasia (BPD; part of the spectrum of chronic lung disease of infancy) is a chronic lung disease in which premature infants, usually those who were treated with supplemental oxygen, require long-term oxygen. The alveoli that are ...
, and
intraventricular hemorrhage
Intraventricular hemorrhage (IVH), also known as intraventricular bleeding, is a bleeding into the brain's ventricular system, where the cerebrospinal fluid is produced and circulates through towards the subarachnoid space. It can result from phys ...
in preterm infants.
Characteristics
Over 100 species have been included in the genus ''Mycoplasma'', a member of the class ''
Mollicutes
Mollicutes is a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin ''mollis'' (meaning "soft" or "pliable"), and ''cutis'' (meaning "skin"). Individuals are very small, typically only 0. ...
.'' They are
parasite
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
s or
commensal
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...
s of humans, animals, and plants. The genus ''Mycoplasma'' uses
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
and
arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
hosts.
Dietary nitrogen availability has been shown to alter
codon bias and genome evolution in ''Mycoplasma'' and ''Phytoplasma''.
''Mycoplasma'' species are among the smallest free-living organisms (about 0.2 - 0.3 µm in diameter).
They have been found in the pleural cavities of cattle suffering from pleuropneumonia. These organisms are often called MLO (mycoplasma-like organisms) or, formerly, PPLO (pleuropneumonia-like organisms).
Important characteristics of ''Mycoplasma'' species
# Cell wall is absent and
plasma membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...
forms the outer boundary of the cell.
# Due to the absence of cell walls these organisms can change their shape and are
pleomorphic.
# Lack of nucleus and other membrane-bound organelles.
# Genetic material is a single
DNA duplex and is naked.
# Ribosomes are
70S
Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to for ...
type.
# Possess a replicating disc at one end which assists replication process and also the separation of the genetic materials.
#
Heterotrophic nutrition
Heterotrophic nutrition is a mode of nutrition in which organisms depend upon other organisms for food to survive. They can't make their own food like Green plants. Heterotrophic organisms have to take in all the organic substances they need to sur ...
. Some live as
saprophytes but the majority are parasites of plants and animals. The parasitic nature is due to the inability of mycoplasmal bacteria to synthesise the required growth factor.
Cell and colony morphology
Due to the lack of a rigid cell wall, ''Mycoplasma'' species (like all ''Mollicutes'') can contort into a broad range of shapes, from round to oblong. They are
pleomorphic and therefore cannot be identified as rods,
cocci
A coccus (plural cocci) is any bacterium or archaeon that has a spherical, ovoid, or generally round shape. Bacteria are categorized based on their shapes into three classes: cocci (spherical-shaped), bacillus (rod-shaped) and spiral ( of whi ...
or
spirochetes
A spirochaete () or spirochete is a member of the phylum Spirochaetota (), (synonym Spirochaetes) which contains distinctive diderm (double-membrane) gram-negative bacteria, most of which have long, helically coiled (corkscrew-shaped or s ...
.
Colonies show the typical „fried egg” appearance (about 0.5 mm in diameter).
Reproduction
In 1954, using phase-contrast microscopy, continual observations of live cells have shown that ''Mycoplasma'' species ("mycoplasmas", formerly called pleuropneumonia-like organisms, PPLO, now classified as ''Mollicutes'') and
L-form bacteria
L-form bacteria, also known as L-phase bacteria, L-phase variants or cell wall-deficient (CWD) bacteria, are growth forms derived from different bacteria. They lack cell walls. Peptidoglycan (murein) is absent. Two types of L-forms are distinguish ...
(previously also called L-phase bacteria) do not proliferate by binary fission, but by a uni- or multi-polar
budding
Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is know ...
mechanism. Microphotograph series of growing microcultures of different strains of PPLOs, L-form bacteria and, as a control, a Micrococcus species (dividing by binary fission) have been presented.
Additionally, electron microscopic studies have been performed.
Phylogeny
Previously, ''Mycoplasma'' species (often commonly called "mycoplasmas", now classified as ''
Mollicutes
Mollicutes is a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin ''mollis'' (meaning "soft" or "pliable"), and ''cutis'' (meaning "skin"). Individuals are very small, typically only 0. ...
'') were sometimes considered stable
L-form bacteria
L-form bacteria, also known as L-phase bacteria, L-phase variants or cell wall-deficient (CWD) bacteria, are growth forms derived from different bacteria. They lack cell walls. Peptidoglycan (murein) is absent. Two types of L-forms are distinguish ...
or even viruses, but phylogenetic analysis has identified them as bacteria that have lost their cell walls in the course of evolution.
The genus ''Mycoplasma'' as originally described is highly paraphyletic, as such it was redescibed by Gupta et al. 2018 and its emendation was accompanied by the removal of 78 species. The currently accepted taxonomy is based on the
List of Prokaryotic names with Standing in Nomenclature
List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclature ...
(LPSN)
and
National Center for Biotechnology Information
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The ...
(NCBI)
Unassigned species:
* "''Ca.'' M. aoti"
Barker et al. 2011
* "''Ca.'' M. corallicola"
Neulinger et al. 2009
* "''Ca.'' M. erythrocervae"
Watanabe et al. 2010
* "''Ca.'' M. haematocervi"
corrig. Watanabe et al. 2010
* "''Ca.'' M. haematodidelphidis"
corrig. Messick et al. 2002
* "''Ca.'' M. haematomacacae"
corrig. Maggi et al. 2013
* "''Ca.'' M. haematominiopteri"
corrig. Millán et al. 2015
* "''Ca.'' M. haematonasua"
Collere et al. 2021
* "''Ca.'' M. haematoparvum"
Sykes et al. 2005
* "''Ca.'' M. haematovis"
corrig. Hornok et al. 2009
* "''Ca.'' M. haemoalbiventris"
Pontarolo et al. 2021
* "''Ca.'' M. haemobovis"
Meli et al. 2010
* "''Ca.'' M. haemomeles"
Harasawa, Orusa &Giangaspero 2014
* "''Ca.''
M. haemomuris"
(Mayer 1921) Neimark et al. 2002
* "''Ca.'' M. haemoparvum"
Kenny et al. 2004
* "''Ca.'' M. haemosphiggurus"
Valente et al. 2021
* ''M. hafezii''
Ziegler et al. 2019
* "''
M. incognitus''"
Lo et al. 1989
* "''M. insons''"
May et al. 2007
* "''Ca.'' M. kahanei"
Neimark et al. 2002
* ''M. miroungigenitalium''
Volokhov et al. 2022
* ''M. miroungirhinis''
Volokhov et al. 2022
* "''M. monodon''"
Ghadersohi & Owens 1998
* ''M. phocoenae''
Volokhov et al. 2022
* ''M. phocoeninasale''
Volokhov et al. 2022
* "''M. pneumophila''"
Lyerova et al. 2008
* "''Ca.'' M. ravipulmonis"
Neimark, Mitchelmore & Leach 1998
* ''M. seminis''
Fischer et al. 2021
* "''M. sphenisci''"
Frasca et al. 2005
* "''M. tauri''"
Spergser et al. 2021
* "''M. timone''"
Greub & Raoult 2001
* "''Ca.'' M. tructae"
Sanchez et al. 2020
* "''Ca.'' M. turicense"
corrig. Willi et al. 2006
* "''M. volis''"
Dillehay et al. 1995
* "''M. vulturii''"
Oaks et al. 2004
Laboratory contaminant
''Mycoplasma'' species are often found in research laboratories as contaminants in
cell culture
Cell culture or tissue culture is the process by which cells are grown under controlled conditions, generally outside of their natural environment. The term "tissue culture" was coined by American pathologist Montrose Thomas Burrows. This te ...
. Mycoplasmal cell culture contamination occurs due to contamination from individuals or contaminated cell culture
medium
Medium may refer to:
Science and technology
Aviation
*Medium bomber, a class of war plane
* Tecma Medium, a French hang glider design
Communication
* Media (communication), tools used to store and deliver information or data
* Medium of ...
ingredients. ''Mycoplasma'' cells are physically small – less than 1 µm, so are difficult to detect with a conventional
microscope
A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...
.
Mycoplasmae may induce cellular changes, including
chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
aberrations, changes in
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
and cell growth. Severe ''Mycoplasma'' infections may destroy a cell line. Detection techniques include
DNA probe
In molecular biology, a hybridization probe (HP) is a fragment of DNA or RNA of usually 15–10000 nucleotide long which can be radioactively or fluorescently labeled. HP can be used to detect the presence of nucleotide sequences in analyzed RN ...
,
enzyme immunoassays,
PCR, plating on sensitive
agar
Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori (''Gracilaria'') and "tengusa" (''Gelidiaceae''). As found in nature, agar is ...
and staining with a
DNA stain including
DAPI
DAPI (pronounced 'DAPPY', /ˈdæpiː/), or 4′,6-diamidino-2-phenylindole, is a fluorescent stain that binds strongly to adenine–thymine-rich regions in DNA. It is used extensively in fluorescence microscopy. As DAPI can pass through an inta ...
or
Hoechst Hoechst, Hochst, or Höchst may refer to:
* Hoechst AG, a former German life-sciences company
* Hoechst stain, one of a family of fluorescent DNA-binding compounds
* Höchst (Frankfurt am Main), a city district of Frankfurt am Main, Germany
** Fra ...
.
An estimated 11 to 15% of U.S. laboratory cell cultures are contaminated with mycoplasma.
A
Corning study showed that half of U.S. scientists did not test for ''Mycoplasma'' contamination in their cell cultures. The study also stated that, in former Czechoslovakia, 100% of cell cultures that were not routinely tested were contaminated while only 2% of those routinely tested were contaminated (study p. 6). Since the U.S. contamination rate was based on a study of companies that routinely checked for ''Mycoplasma'', the actual contamination rate may be higher. European contamination rates are higher and that of other countries are higher still (up to 80% of Japanese cell cultures).
About 1% of published
Gene Expression Omnibus
Gene Expression Omnibus (GEO) is a database for gene expression profiling and RNA methylation profiling managed by the National Center for Biotechnology Information (NCBI). These high-throughput screening genomics data are derived from microarray ...
data may have been compromised.
[Link](_blank)
into RNAnet showing contamination of GEO. Press plot and drag blue crosshairs to expose links to description of experiments on human RNA samples Several antibiotic-containing formulations of antimycoplasmal reagents have been developed over the years.
by Roche, MRA by ICN
Plasmocin
by Invivogen and more recentl
by TOKU-E.
Synthetic mycoplasma genome
A chemically synthesized genome of a mycoplasmal cell based entirely on synthetic DNA which can self-replicate has been referred to as ''
Mycoplasma laboratorium
''Mycoplasma laboratorium'' or Synthia refers to a synthetic strain of bacterium. The project to build the new bacterium has evolved since its inception. Initially the goal was to identify a minimal set of genes that are required to sustain li ...
''.
Pathogenicity
The P1 antigen is the primary
virulence factor
Virulence factors (preferably known as pathogenicity factors or effectors in plant science) are cellular structures, molecules and regulatory systems that enable microbial pathogens (bacteria, viruses, fungi, and protozoa) to achieve the following ...
of mycoplasma. P1 is a membrane associated protein that allows adhesion to
epithelial cells
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...
. The P1 receptor is also expressed on
erythrocytes
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
which can lead to autoantibody
agglutination
In linguistics, agglutination is a morphological process in which words are formed by stringing together morphemes, each of which corresponds to a single syntactic feature. Languages that use agglutination widely are called agglutinative lang ...
from mycobacteria infection. Several ''Mycoplasma'' species can
cause disease, including ''M. pneumoniae'', which is an important cause of
atypical pneumonia
Atypical pneumonia, also known as walking pneumonia, is any type of pneumonia not caused by one of the pathogens most commonly associated with the disease. Its clinical presentation contrasts to that of "typical" pneumonia. A variety of microorgan ...
(formerly known as "walking pneumonia"), and ''M. genitalium'', which has been associated with
pelvic inflammatory diseases. Mycoplasma infections in humans are associated with skin eruptions in 17% of cases.
Sexually transmitted infections
''Mycoplasma'' and ''Ureaplasma'' species are not part of the normal
vaginal flora
Vaginal flora, vaginal microbiota or vaginal microbiome are the microorganisms that colonize the vagina. They were discovered by the German gynecologist Albert Döderlein in 1892 and are part of the overall human flora.
The amount and type o ...
. Some ''Mycoplasma'' species are spread through sexual contact.
[
]
Infertility
Some ''Mycoplasma'' species have a negative effect on fertility. '' M. hominis'' causes ''male sterility
Cytoplasmic male sterility is total or partial male sterility in plants as the result of specific nuclear and mitochondrial interactions. Male sterility is the failure of plants to produce functional anthers, pollen, or male gametes.
Background
Jo ...
/Genitals inflammation'' in humans.
Infant mortality
Low birth-weight, preterm infants are susceptible to ''Mycoplasma'' infections.
Links to cancer
Several species of ''Mycoplasma'' are frequently detected in different types of cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
cells. These species are:
* ''M. fermentans''
* ''M. genitalium''
* ''M. hyorhinis''
* ''M. penetrans''
* ''U. urealyticum''
The majority of these ''Mycoplasma'' species have shown a strong correlation to malignant transformation
Malignant transformation is the process by which cells acquire the properties of cancer. This may occur as a primary process in normal tissue, or secondarily as ''malignant degeneration'' of a previously existing benign tumor.
Causes
There are ...
in mammalian cells ''in vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...
''.
''Mycoplasma'' infection and host cell transformation
The presence of ''Mycoplasma'' was first reported in samples of cancer tissue in the 1960s. Since then, several studies tried to find and prove the connection between ''Mycoplasma'' and cancer, as well as how the bacterium might be involved in the formation of cancer. Several studies have shown that cells that are chronically infected with the bacteria go through a multistep transformation. The changes caused by chronic mycoplasmal infections occur gradually and are both morphological and genetic. The first visual sign of infection is when the cells gradually shift from their normal form to sickle-shaped. They also become hyperchromatic
Dysplasia is any of various types of abnormal growth or development of cells (microscopic scale) or organs (macroscopic scale), and the abnormal histology or anatomical structure(s) resulting from such growth. Dysplasias on a mainly microscopic ...
due to an increase of DNA in the nucleus of the cells. In later stages, the cells lose the need for solid support to grow and proliferate, as well as the normal contact-dependent inhibition cells.
Possible intracellular mechanisms of mycoplasmal malignant transformation
Karyotypic changes related to mycoplasma infections
Cells infected with ''Mycoplasma'' for an extended period of time show significant chromosomal abnormalities. These include the addition of chromosomes, the loss of entire chromosomes, partial loss of chromosomes, and chromosomal translocation
In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal-, and Robertsonian translocation. Reciprocal translo ...
. All of these genetic abnormalities may contribute to the process of malignant transformation. Chromosomal translocation and extra chromosomes help create abnormally high activity of certain proto-oncogenes
An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels. , which caused by these genetic abnormalities and include those encoding c-myc
''Myc'' is a family of regulator genes and proto-oncogenes that code for transcription factors. The ''Myc'' family consists of three related human genes: ''c-myc'' (MYC), ''l-myc'' (MYCL), and ''n-myc'' (MYCN). ''c-myc'' (also sometimes referre ...
, HRAS
GTPase HRas, from "Harvey Rat sarcoma virus", also known as transforming protein p21 is an enzyme that in humans is encoded by the gene. The ''HRAS'' gene is located on the short (p) arm of chromosome 11 at position 15.5, from base pair 522,241 t ...
, and vav. The activity of proto-oncogenes is not the only cellular function that is affected; tumour suppressor genes are affected by the chromosomal changes induced by mycoplasma, as well. Partial or complete loss of chromosomes causes the loss of important genes involved in the regulation of cell proliferation. Two genes whose activities are markedly decreased during chronic infections with mycoplasma are the Rb and the p53
p53, also known as Tumor protein P53, cellular tumor antigen p53 (UniProt name), or transformation-related protein 53 (TRP53) is a regulatory protein that is often mutated in human cancers. The p53 proteins (originally thought to be, and often s ...
tumour suppressor genes. Another possible mechanism of carcinogenesis is RAC1 activation by a small GTPase-like protein fragment of Mycoplasma. A major feature that differentiates mycoplasmas from other carcinogenic pathogens is that the mycoplasmas do not cause the cellular changes by insertion of their own genetic material into the host cell. The exact mechanism by which the bacterium causes the changes is not yet known.
; Partial reversibility of malignant transformations
The malignant transformation induced by ''Mycoplasma'' species is also different from that caused by other pathogens in that the process is reversible. The state of reversal is, however, only possible up to a certain point during the infection. The window of time when reversibility is possible varies greatly; it depends primarily on the ''Mycoplasma'' involved. In the case of ''M. fermentans'', the transformation is reversible until around week 11 of infection and starts to become irreversible between weeks 11 and 18. If the bacteria are killed using antibiotics
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...
(i.e. ciprofloxacin
Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin infec ...
or Clarithromycin
Clarithromycin, sold under the brand name Biaxin among others, is an antibiotic used to treat various bacterial infections. This includes strep throat, pneumonia, skin infections, ''H. pylori'' infection, and Lyme disease, among others. Clarith ...
) before the irreversible stage, the infected cells should return to normal.
Connections to cancer ''in vivo'' and future research
Epidemiologic, genetic, and molecular 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 (BPH-1) that were not tumorigenic after 19 weeks of exposure.
Types of cancer associated with ''Mycoplasma''
Colon cancer
Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel mo ...
: In a study to understand the effects of ''Mycoplasma'' contamination on the quality of cultured human colon cancer cells, a positive correlation was found between the number of'' M. hyorhinis'' cells present in the sample and the percentage of CD133-positive cells (a glycoprotein with an unknown function).
Gastric cancer
Stomach cancer, also known as gastric cancer, is a cancer that develops from the lining of the stomach. Most cases of stomach cancers are gastric carcinomas, which can be divided into a number of subtypes, including gastric adenocarcinomas. Lymph ...
: Strong evidence indicates the infection of'' M. hyorhinis'' contributes to the development of cancer within the stomach and increases the likelihood of malignant cancer cell development.
Lung cancer
Lung cancer, also known as lung carcinoma (since about 98–99% of all lung cancers are carcinomas), is a malignant lung tumor characterized by uncontrolled cell growth in tissue (biology), tissues of the lung. Lung carcinomas derive from tran ...
: Studies on lung cancer have supported the belief that more than a coincidental positive correlation exists between the appearance of'' Mycoplasma'' strains in patients and the infection with tumorigenesis.
Prostate cancer
Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...
: p37, a protein encoded for by ''M. hyorhinis'', has been found to promote the invasiveness of prostate cancer cells. The protein also causes the growth, morphology, and gene expression of the cells to change, causing them to become a more aggressive phenotype.
Renal cancer
Kidney cancer, also known as renal cancer, is a group of cancers that starts in the kidney. Symptoms may include blood in the urine, lump in the abdomen, or back pain. Fever, weight loss, and tiredness may also occur. Complications can include spr ...
: Patients with renal cell carcinoma (RCC) exhibited a significantly high amount of Mycoplasma sp. compared with the healthy control group. This suggests ''Mycoplasma'' may play a role in the development of RCC.
See also
* International Organization for Mycoplasmology The International Organisation for Mycoplasmology (IOM) is a non-profit making organisation founded in 1976. It promotes the study of mycoplasmas (mollicutes), bacteria without a cell wall, and the diseases associated with them.
Areas of research ...
(IOM)
* Sexually transmitted disease
Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal diseases, are infections that are spread by sexual activity, especially vaginal intercourse, anal sex, and oral ...
* Vaginal flora
Vaginal flora, vaginal microbiota or vaginal microbiome are the microorganisms that colonize the vagina. They were discovered by the German gynecologist Albert Döderlein in 1892 and are part of the overall human flora.
The amount and type o ...
* Vaginal infection
Vaginitis, also known as vulvovaginitis, is inflammation of the vagina and vulva. Symptoms may include itching, burning, pain, discharge, and a bad smell. Certain types of vaginitis may result in complications during pregnancy.
The three main ...
* Vaginal disease
A vaginal disease is a pathological condition that affects part or all of the vagina.
Types
Sexually transmitted infections
Sexually transmitted disease that affect the vagina include:
*Herpes genitalis. The herpes simplex virus (HSV) can infect ...
* Vaginal health
In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen. ...
* Phytoplasma
Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-lik ...
* List of bacterial orders
This article lists the orders of the Bacteria. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)
and the phylogeny is based on 16S ...
* List of bacteria genera This article lists the genera of the bacteria. The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI). However many taxonomic names are ...
References
External links
Ureaplasma Infection: eMedicine Infectious Diseases
{{Authority control
Mycoplasmataceae
Bacteria genera
Rodent-carried diseases
Sexually transmitted diseases and infections
Infectious causes of cancer
Infertility
Bacterial vaginosis