Mycoplasma pneumoniae

Last updated

Mycoplasma pneumoniae
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Phylum: Mycoplasmatota
Class: Mollicutes
Order: Mycoplasmatales
Family: Mycoplasmataceae
Genus: Mycoplasma
Species:
M. pneumoniae
Binomial name
Mycoplasma pneumoniae
Somerson et al., 1963

Mycoplasma pneumoniae is a species of very small-cell bacteria that lack a cell wall, in the class Mollicutes. M. pneumoniae is a human pathogen that causes the disease Mycoplasma pneumonia, a form of atypical bacterial pneumonia related to cold agglutinin disease.

Contents

It is one of the smallest self-replicating organisms and its discovery traces back to 1898 when Nocard and Roux isolated a microorganism linked to cattle pneumonia. This microbe shared characteristics with pleuropneumonia-like organisms (PPLOs), which were soon linked to pneumonias and arthritis in several animals. A significant development occurred in 1944 when Monroe Eaton cultivated an agent thought responsible for human pneumonia in embryonated chicken eggs, referred to as the "Eaton agent." This agent was classified as a bacteria due to its cultivation method and because antibiotics were effective in treating the infection, questioning its viral nature. In 1961, a researcher named Robert Chanock, collaborating with Leonard Hayflick, revisited the Eaton agent and posited it could be a mycoplasma, a hypothesis confirmed by Hayflick’s isolation of a unique mycoplasma, later named Mycoplasma pneumoniae. Hayflick’s discovery proved M. pneumoniae was responsible for causing human pneumonia.

Taxonomically, Mycoplasma pneumoniae is part of the Mollicutes class, characterized by their lack of a peptidoglycan cell wall, making them inherently resistant to antibiotics targeting cell wall synthesis, such as beta-lactams. With a reduced genome and metabolic simplicity, mycoplasmas are obligate parasites with limited metabolic pathways, relying heavily on host resources. This bacterium uses a specialized attachment organelle to adhere to respiratory tract cells, facilitating motility and cell invasion. The persistence of M. pneumoniae infections even after treatment is associated with its ability to mimic host cell surface composition.

Pathogenic mechanisms of M. pneumoniae involve host cell adhesion and cytotoxic effects, including cilia loss and hydrogen peroxide release, which lead to respiratory symptoms and complications such as bronchial asthma and chronic obstructive pulmonary disease. Additionally, the bacterium produces a unique CARDS toxin, contributing to inflammation and respiratory distress. Treatment of M. pneumoniae infections typically involves macrolides or tetracyclines, as these antibiotics inhibit protein synthesis, though resistance has been increasing, particularly in Asia. This resistance predominantly arises from mutations in the 23S rRNA gene, which interfere with macrolide binding, complicating management and necessitating alternative treatment strategies.

Discovery and history

In 1898, Nocard and Roux isolated an agent assumed to be the cause of cattle pneumonia and named it microbe de la peripneumonie [1] [2] [3] [4] [5] [6] Microorganisms from other sources, having properties similar to the pleuropneumonia organism (PPO) of cattle, soon came to be known as pleuropneumonia-like organisms (PPLO), but their true nature remained unknown. [1] [2] [3] [4] Many PPLO were later proven to be the cause of pneumonias and arthritis in several lower animals. [1] [7] [8] [9]

In 1944, Monroe Eaton used embryonated chicken eggs to cultivate an agent thought to be the cause of human primary atypical pneumonia (PAP), commonly known as "walking pneumonia." [10] This unknown organism became known as the "Eaton agent". [11] At that time, Eaton's use of embryonated eggs, then used for cultivating viruses, supported the idea that the Eaton agent was a virus. Yet it was known that PAP was amenable to treatment with broad-spectrum antibiotics, making a viral etiology suspect. [1] [2] [7] [12] [13]

Robert Chanock, a researcher from the NIH who was studying the Eaton agent as a virus, visited the Wistar Institute in Philadelphia in 1961 to obtain a cell culture of a normal human cell strain developed by Leonard Hayflick. This cell strain was known to be exquisitely sensitive to isolate and grow human viruses. Chanock told Hayflick of his research on the Eaton agent, and his belief that its viral nature was questionable. Although Hayflick knew little about the current research on this agent, his doctoral dissertation had been done on animal diseases caused by PPLO. Hayflick knew that many lower animals suffered from pneumonias caused by PPLOs (later to be termed mycoplasmas). Hayflick reasoned that the Eaton agent might be a mycoplasma, and not a virus. Chanock had never heard of mycoplasmas, and at Hayflick's request sent him egg yolk containing the Eaton agent. [1] [4] [14] [15] [16] [17]

Using a novel agar and fluid medium formulation he had devised, [14] Hayflick isolated a unique mycoplasma from the egg yolk. This was soon proven by Chanock and Hayflick to be the causative agent of PAP. [14] [18] [19] [20] When this discovery became known to Emmy Klieneberger-Nobel of the Lister Institute in London, the world's leading authority on these organisms, she suggested that the organism be named Mycoplasma hayflickiae. [21] Hayflick demurred in favor of Mycoplasma pneumoniae. [22] [23]

This smallest free-living microorganism was the first to be isolated and proven to be the cause of a human disease. For his discovery, Hayflick was presented with the Presidential Award by the International Organization of Mycoplasmology. The inverted microscope under which Hayflick discovered Mycoplasma pneumoniae is kept by the Smithsonian Institution. [20]

Taxonomy and classification

The term mycoplasma (mykes meaning fungus, and plasma, meaning formed) is derived from the fungal-like growth of some mycoplasma species. [6] The mycoplasmas were classified as Mollicutes (“mollis”, meaning soft and “cutis”, meaning skin) in 1960 due to their small size and genome, lack of cell wall, low G+C content and unusual nutritional needs. [6] [24]

Mycoplasmas, which are among the smallest self-replicating organisms, are parasitic species that lack a cell wall and periplasmic space, have reduced genomes, and limited metabolic activity. [6] [25] [26] M. pneumoniae has also been designated as an arginine nonfermenting species. [25] Mycoplasmas are further classified by the sequence composition of 16s rRNA. All mycoplasmas of the pneumoniae group possess similar 16s rRNA variations unique to the group, of which M. pneumoniae has a 6.3% variation in the conserved regions, that suggest mycoplasmas formed by degenerative evolution from the gram-positive eubacterial group that includes bacilli, streptococci, and lactobacilli. [6] [24] [25] M. pneumoniae is a member of the family Mycoplasmataceae and order Mycoplasmatales. [6]

Cell biology

A) Filamentous Mycoplasma pneumoniae cells B) M. pneumoniae cells (M) attached to ciliated mucosal cells by the attachment organelle (indicated by arrow) Mycoplasma pneumoniae cells attached to ciliated mucosal cells.jpeg
A) Filamentous Mycoplasma pneumoniae cells B) M. pneumoniae cells (M) attached to ciliated mucosal cells by the attachment organelle (indicated by arrow)

Mycoplasma pneumoniae cells have an elongated shape that is approximately 0.1–0.2  μm (100–200 nm) in width and 1–2 μm (1000-2000 nm) in length. The extremely small cell size means they are incapable of being examined by light microscopy; a stereomicroscope is required for viewing the morphology of M. pneumoniae colonies, which are usually less than 100 μm in length. [6] The inability to synthesize a peptidoglycan cell wall is due to the absence of genes encoding its formation and results in an increased importance in maintenance of osmotic stability to avoid desiccation. [6] The lack of a cell wall also calls for increased support of the cell membrane(reinforced with sterols), which includes a rigid cytoskeleton composed of an intricate protein network and, potentially, an extracellular capsule to facilitate adherence to the host cell. [6] M. pneumoniae are the only bacterial cells that possess cholesterol in their cell membrane (obtained from the host) and possess more genes that encode for membrane lipoprotein variations than other mycoplasmas, [25] which are thought to be associated with its parasitic lifestyle. M. pneumoniae cells also possess an attachment organelle, which is used in the gliding motility of the organism by an unknown mechanism. [6]

Genomics and metabolic reconstruction

Sequencing of the M. pneumoniae genome in 1996 revealed it is 816,394 bp in size. [24] The genome contains 687 genes that encode for proteins, of which about 56.6% code for essential metabolic enzymes; notably those involved in glycolysis and organic acid fermentation. [6] [24] [25] [27] M. pneumoniae is consequently very susceptible to loss of enzymatic function by gene mutations, as the only buffering systems against functional loss by point mutations are for maintenance of the pentose phosphate pathway and nucleotide metabolism. [27] Loss of function in other pathways is suggested to be compensated by host cell metabolism. [27] In addition to the potential for loss of pathway function, the reduced genome of M. pneumoniae outright lacks a number of pathways, including the TCA cycle, respiratory electron transport chain, and biosynthesis pathways for amino acids, fatty acids, cholesterol and purines and pyrimidines. [6] [25] [27] These limitations make M. pneumoniae dependent upon import systems to acquire essential building blocks from their host or the environment that cannot be obtained through glycolytic pathways. [25] [27] Along with energy costly protein and RNA production, a large portion of energy metabolism is exerted to maintain proton gradients (up to 80%) due to the high surface area to volume ratio of M. pneumoniae cells. Only 12 – 29% of energy metabolism is directed at cell growth, which is unusually low for bacterial cells, and is thought to be an adaptation of its parasitic lifestyle. [27]

Unlike other bacteria, M. pneumoniae uses the codon UGA to code for tryptophan rather than using it as a stop codon. [6] [24]

Comparative metabolomics

Mycoplasma pneumoniae has a reduced metabolome in comparison to other bacterial species. [28]   This means that the pathogen has fewer metabolic reactions in comparison to other bacterial species such as B.subtilis and Escherichia coli . [28] [29]

Metabolic pathway map depicting the enzymes of glycolysis in Mycoplasma pneumoniae.Green boxes signify enzymes that are present in the pathway. The white boxes symbolize missing enzymes. Enzymes of the TCA cycle are missing in M. pneumoniae. The complete pathway can be found at KEGG. Final emptytcamap.jpg
Metabolic pathway map depicting the enzymes of glycolysis in Mycoplasma pneumoniae.Green boxes signify enzymes that are present in the pathway. The white boxes symbolize missing enzymes. Enzymes of the TCA cycle are missing in M. pneumoniae. The complete pathway can be found at KEGG.

Since Mycoplasma pneumoniae has a reduced genome, it has a smaller number of overall paths and metabolic enzymes, which contributes to its more linear metabolome. [28] A linear metabolome causes Mycoplasma pneumoniae to be less adaptable to external factors. [28]   Additionally, since Mycoplasma pneumoniae has a reduced genome, the majority of its metabolic enzymes are essential. [28] This is in contrast to another model organism, Escherichia coli , in which only 15% of its metabolic enzymes are essential. [28] In summary, the linear topology of Mycoplasma pneumoniae's metabolome leads to reduced efficiency in its metabolic reactions, but still maintains similar levels of metabolite concentrations, cellular energetics, adaptability, and global gene expression. [28]

SpeciesM. pneumoniaeL. lactisB. subtilisE. coli
Mean # Of Paths8.175.377.546.12

The table above depicts the mean path length for the metabolomes of M. pneumoniae, E. coli, L. lactis , and B. subtilis. [28] This number describes, essentially, the mean number of reactions that occur in the metabolome. Mycoplasma pneumoniae, on average, has a high number of reactions per path within its metabolome in comparison to other model bacterial species. [28]

One effect of Mycoplasma pneumoniae’s unique metabolome is its longer duplication time. [28] It takes the pathogen significantly more time to duplicate on average compared to other model organism bacteria. [28] This may be due to the fact that Mycoplasma pneumoniae’s metabolome is less efficient than that of Escherichia coli. [28]

The metabolome of Mycoplasma pneumoniae can also be informative in analyzing its pathogenesis. [31] Extensive study of the metabolic network of this organism has led to the identification of biomarkers that can potentially reveal the presence of the extensive complications the bacteria can cause. [31] Metabolomics is increasingly being used as a useful tool for the verification of biomarkers of infectious pathogens. [31]

Pathogenicity

Pathogenicity of Mycoplasma pneumoniae in vasculitic/thrombotic disorders Pathogenicity of Mycoplasma pneumoniae in vasculitic-thrombotic disorders.png
Pathogenicity of Mycoplasma pneumoniae in vasculitic/thrombotic disorders

Mycoplasma pneumoniae parasitizes the respiratory tract epithelium of humans. [6] Adherence to the respiratory epithelial cells is thought to occur via the attachment organelle, followed by evasion of host immune system by intracellular localization and adjustment of the cell membrane composition to mimic the host cell membrane.[ citation needed ]Mycoplasma pneumoniae grows exclusively by parasitizing mammals. Reproduction, therefore, is dependent upon attachment to a host cell. According to Waites and Talkington, specialized reproduction occurs by “binary fission, temporally linked with duplication of its attachment organelle, which migrates to the opposite pole of the cell during replication and before nucleoid separation”. [6] Mutations that affect the formation of the attachment organelle not only hinder motility and cell division, but also reduce the ability of M. pneumoniae cells to adhere to the host cell. [25]

Cytoadherence

Adherence of M. pneumoniae to a host cell (usually a respiratory tract cell, but occasionally an erythrocyte or urogenital lining cell) is the initiating event for pneumonic disease and related symptoms. [6] The specialized attachment organelle is a polar, electron dense and elongated cell extension that facilitates motility and adherence to host cells. [6] [25] It is composed of a central filament surrounded by an intracytoplasmic space, along with a number of adhesins and structural and accessory proteins localized at the tip of the organelle. [6] [25] A variety of proteins are known to contribute to the formation and functionality of the attachment organelle, including the accessory proteins HMW1–HMW5, P30, P56, and P90 that confer structure and adhesin support, and P1, P30 and P116 which are involved directly in attachment. [6] [32] [33] This network of proteins participates not only in the initiation of attachment organelle formation and adhesion but also in motility. [33] The P1 adhesin (trypsin-sensitive protein) is a 120 kDa protein highly clustered on the surface of the attachment organelle tip in virulent mycoplasmas. [6] [33] [34] Both the presence of P1 and its concentration on the cell surface are required for the attachment of M. pneumoniae to the host cell. M. pneumoniae cells treated with monoclonal antibodies specific to the immunogenic C-terminus of the P1 adhesin have been shown to be inhibited in their ability to attach to the host cell surface by approximately 75%, suggesting P1 is a major component in adherence. [6] [32] [33] These antibodies also decreased the ability of the cell to glide quickly, which may contribute to decreased adherence to the host by hindering their capacity to locate a host cell. [32] Furthermore, mutations in P1 or degradation by trypsin treatment yield avirulent M. pneumoniae cells. [6] Loss of proteins in the cytoskeleton involved in the localization of P1 in the tip structure, such as HMW1–HMW3, also cause avirulence due to the lack of adhesin clustering. [33] [34] Another protein considered to play an important role in adherence is P30, as M. pneumoniae cells with mutations in this protein or that have had antibodies raised against P30 are incapable of adhering to host cells. [6] [25] P30 is not involved in the localization of P1 in the tip structure since P1 is trafficked to the attachment organelle in P30 mutants, but rather it may function as a receptor-binding accessory adhesin. [25] [34] P30 mutants also display distinct morphological features such as multiple lobes and a rounded shape as opposed to elongated, which suggests P30 may interact with the cytoskeleton during formation of the attachment organelle. [25] A number of eukaryotic cell surface components have been implicated in the adherence of M. pneumoniae cells to the respiratory tract epithelium. Among them are sialoglycoconjugates, sulfated glycolipids, glycoproteins, fibronectin, and neuraminic acid receptors. [6] [32] [35] Lectins on the surface of the bacterial cells are capable of binding oligosaccharide chains on glycolipids and glycoproteins to facilitate attachment, in addition to the proteins TU and pyruvate dehydrogenase E1 β, which bind to fibronectin. [6] [32]

Schematic of the phosphorylated proteins in the attachment organelle of Mycoplasma pneumoniae Schematic of the phosphorylated proteins in the attachment organelle in Mycoplasma pneumoniae.jpeg
Schematic of the phosphorylated proteins in the attachment organelle of Mycoplasma pneumoniae

Intracellular localization

Mycoplasma pneumoniae fuses with host cells and survive intracellularly. Thus it can evade host immune system detection, resist antibiotic treatment, and cross mucosal barriers,. [6] [26] In addition to the close physical proximity of M. pneumoniae and host cells, the lack of cell wall and peculiar cell membrane components, like cholesterol, may facilitate fusion. Internal localization may produce chronic or latent infections as M. pneumoniae is capable of persisting, synthesizing DNA, and replicating within the host cell even after treatment with antibiotics. [26] The exact mechanism of intracellular localization is unknown, however the potential for cytoplasmic sequestration within the host explains the difficulty in completely eliminating M. pneumoniae infections in afflicted individuals. [6]

Immune response

In addition to evasion of host immune system by intracellular localization, M. pneumoniae can change the composition of its cell membrane to mimic the host cell membrane and avoid detection by immune system cells. M. pneumoniae cells possess a number of protein and glycolipid antigens that elicit immune responses, but variation of these surface antigens would allow the infection to persist long enough for M. pneumoniae cells to fuse with host cells and escape detection. The similarity between the compositions of M. pneumoniae and human cell membranes can also result in autoimmune responses in several organs and tissues. [6]

Cytotoxicity and organismal effects

The main cytotoxic effect of M. pneumoniae is local disruption of tissue and cell structure along the respiratory tract epithelium due to its attachment to host cells. Attachment of the bacteria to host cells can result in loss of cilia, a reduction in metabolism, biosynthesis, and import of macromolecules, and, eventually, infected cells may be shed from the epithelial lining. [6] Local damage may also be a result of lactoferrin acquisition and subsequent hydroxyl radical, superoxide anion and peroxide formation. [6]

Secondly, M. pneumoniae produces a unique virulence factor known as Community Acquired Respiratory Distress Syndrome (CARDS) toxin. [36] The CARDS toxin most likely aids in the colonization and pathogenic pathways of M. pneumoniae, leading to inflammation and airway dysfunction.

The third virulence factor is the formation of hydrogen peroxide in M. pneumoniae infections. [6] When M. pneumoniae is attached to erythrocytes, hydrogen peroxide diffuses from the bacteria to the host cell without it being detoxified by catalase or peroxidase, thus injuring the host cell by reducing glutathione, damaging lipid membranes and causing protein denaturation, i.e. oxidation of heme and hemolysis. [6] [35]

Most recently it was shown that hydrogen peroxide plays a minor if any role in haemolysis, but that hydrogen sulfide is the true culprit. [37]

The cytotoxic effects of M. pneumoniae infections translate into common symptoms like coughing and lung irritation that may persist for months after infection has subsided. Local inflammation and hyperresponsiveness by infection induced cytokine production has been associated with chronic conditions such as bronchial asthma and has also been linked to progression of symptoms in individuals with cystic fibrosis and COPD. [6]

Antimicrobial activity

Infections can be treated with oral antibiotics from the macrolide family, which work by inhibiting the Mycoplasma protein biosynthesis. Historically, erythromycin is the oldest drug. As first choice, azithromycin or clarithromycin are used, as they have more convenient pharmacokinetics than erythromycin : they only need to be taken once or twice and not four times a day and they have fewer side effects. Alternatively, tetracyclines (eg, doxycycline), and respiratory fluoroquinolones (eg, levofloxacin or moxifloxacin) can be used; they have an undesirable side effect profile in children. Beta-lactams such as penicillin are completely ineffective, because they target the cell wall synthesis.[ citation needed ]

Resistance

Resistance to macrolides has been reported as early as 1967; However resistance has been increasing with increasing use since 2000. Resistance in the 2020s has been highest in Asia, as high as 100%, while rates in the United States have varied from 3.5% to 13%. A single base mutation in the V region of 23S rRNA, like A2063/2064G [38] is responsible for more than 90% of the macrolide-resistant infections. [39]

Since routine culture and susceptibility testing is not performed, as M. pneumoniae is difficult to grow, clinicians will select an antibiotic based on an estimate of local resistance, on treatment response and on other factors.[ which? ] [38]

See also

External videos
Nuvola apps kaboodle.svg Robert Chanock and the Eaton Agent, Leonard Hayflick interview, 61st of 187 parts, Web of Stories. [19]

Related Research Articles

<i>Mycoplasma genitalium</i> Species of bacterium

Mycoplasma genitalium is a sexually transmitted, small and pathogenic bacterium that lives on the mucous epithelial cells of the urinary and genital tracts in humans. Medical reports published in 2007 and 2015 state that Mgen is becoming increasingly common. Resistance to multiple antibiotics, including the macrolide azithromycin, which until recently was the most reliable treatment, is becoming prevalent. The bacterium was first isolated from the urogenital tract of humans in 1981, and was eventually identified as a new species of Mycoplasma in 1983. It can cause negative health effects in men and women. It also increases the risk for HIV spread with higher occurrences in those previously treated with the azithromycin antibiotics.

<span class="mw-page-title-main">Pneumonia</span> Inflammation of the alveoli of the lungs

Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severity of the condition is variable.

<i>Mycoplasma</i> Genus of bacteria

Mycoplasma is a genus of bacteria that, like the other members of the class Mollicutes, lack a cell wall, and its peptidoglycan, around their cell membrane. The absence of peptidoglycan makes them naturally resistant to antibiotics such as the beta-lactam antibiotics that target cell wall synthesis. They can be parasitic or saprotrophic. Several species are pathogenic 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 are among the smallest organisms yet discovered, can survive without oxygen, and come in various shapes. For example, M. genitalium is flask-shaped, while M. pneumoniae is more elongated, many Mycoplasma species are coccoid. Hundreds of Mycoplasma species infect animals.

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 microorganisms can cause it. When it develops independently from another disease, it is called primary atypical pneumonia (PAP).

Mycoplasma hominis is a species of bacteria in the genus Mycoplasma. M. hominis has the ability to penetrate the interior of human cells. Along with ureaplasmas, mycoplasmas are the smallest free-living organisms known.

<span class="mw-page-title-main">Leonard Hayflick</span> American anatomist (1928–2024)

Leonard Hayflick was an American anatomist who was Professor of Anatomy at the UCSF School of Medicine, and was Professor of Medical Microbiology at Stanford University School of Medicine. He was also past president of the Gerontological Society of America and was a founding member of the council of the National Institute on Aging (NIA). The recipient of a number of research prizes and awards, including the 1991 Sandoz Prize for Gerontological Research, he studied the ageing process for more than fifty years. He is known for discovering that normal human cells divide for a limited number of times in vitro. This is known as the Hayflick limit. His discoveries overturned a 60-year old dogma that all cultured cells are immortal. Hayflick demonstrated that normal cells have a memory and can remember at what doubling level they have reached. He demonstrated that his normal human cell strains were free from contaminating viruses. His cell strain WI-38 soon replaced primary monkey kidney cells and became the substrate for the production of most of the world's human virus vaccines. Hayflick discovered that the etiological agent of primary atypical pneumonia was not a virus as previously believed. He was the first to cultivate the causative organism called a mycoplasma, the smallest free-living organism, which Hayflick isolated on a unique culture medium that bears his name. He named the organism Mycoplasma pneumoniae.

<i>Streptococcus pneumoniae</i> Species of bacterium

Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic member of the genus Streptococcus. S. pneumoniae cells are usually found in pairs (diplococci) and do not form spores and are non motile. As a significant human pathogenic bacterium S. pneumoniae was recognized as a major cause of pneumonia in the late 19th century, and is the subject of many humoral immunity studies.

<i>Coxiella burnetii</i> Species of bacterium

Coxiella burnetii is an obligate intracellular bacterial pathogen, and is the causative agent of Q fever. The genus Coxiella is morphologically similar to Rickettsia, but with a variety of genetic and physiological differences. C. burnetii is a small Gram-negative, coccobacillary bacterium that is highly resistant to environmental stresses such as high temperature, osmotic pressure, and ultraviolet light. These characteristics are attributed to a small cell variant form of the organism that is part of a biphasic developmental cycle, including a more metabolically and replicatively active large cell variant form. It can survive standard disinfectants, and is resistant to many other environmental changes like those presented in the phagolysosome.

Mycoplasma pneumonia is a form of bacterial pneumonia caused by the bacterium Mycoplasma pneumoniae.

Mollicutes is a class of bacteria distinguished by the absence of a cell wall. The word "Mollicutes" is derived from the Latin mollis, and cutis. Individuals are very small, typically only 0.2–0.3 μm in size and have a very small genome size. They vary in form, although most have sterols that make the cell membrane somewhat more rigid. Many are able to move about through gliding, but members of the genus Spiroplasma are helical and move by twisting. The best-known genus in the Mollicutes is Mycoplasma. Colonies show the typical "fried-egg" appearance.

<i>Chlamydia pneumoniae</i> Species of bacterium

Chlamydia pneumoniae is a species of Chlamydia, an obligate intracellular bacterium that infects humans and is a major cause of pneumonia. It was known as the Taiwan acute respiratory agent (TWAR) from the names of the two original isolates – Taiwan (TW-183) and an acute respiratory isolate designated AR-39. Briefly, it was known as Chlamydophila pneumoniae, and that name is used as an alternate in some sources. In some cases, to avoid confusion, both names are given.

Community-acquired pneumonia (CAP) refers to pneumonia contracted by a person outside of the healthcare system. In contrast, hospital-acquired pneumonia (HAP) is seen in patients who have recently visited a hospital or who live in long-term care facilities. CAP is common, affecting people of all ages, and its symptoms occur as a result of oxygen-absorbing areas of the lung (alveoli) filling with fluid. This inhibits lung function, causing dyspnea, fever, chest pains and cough.

Chlamydia felis is a Gram-negative, obligate intracellular bacterial pathogen that infects cats. It is endemic among domestic cats worldwide, primarily causing inflammation of feline conjunctiva, rhinitis and respiratory problems. C. felis can be recovered from the stomach and reproductive tract. Zoonotic infection of humans with C. felis has been reported. Strains FP Pring and FP Cello have an extrachromosomal plasmid, whereas the FP Baker strain does not. FP Cello produces lethal disease in mice, whereas the FP Baker does not. An attenuated FP Baker strain, and an attenuated 905 strain, are used as live vaccines for cats.

Eaton's agar is a type of agar media is used to grow Mycoplasma pneumoniae.

Pneumococcal infection is an infection caused by the bacterium Streptococcus pneumoniae.

Atypical bacteria are bacteria that do not get colored by gram-staining but rather remain colorless: they are neither Gram-positive nor Gram-negative. These include the Chlamydiaceae, Legionella and the Mycoplasmataceae ; the Spirochetes and Rickettsiaceae are also often considered atypical.

<span class="mw-page-title-main">Robert M. Chanock</span> American pediatrician and virologist

Robert Merritt Chanock was an American pediatrician and virologist who made major contributions to the prevention and treatment of childhood respiratory infections in more than 50 years spent at the National Institute of Allergy and Infectious Diseases.

Chronic Mycoplasma pneumonia and Chlamydia pneumonia infections are associated with the onset and exacerbation of asthma. These microbial infections result in chronic lower airway inflammation, impaired mucociliary clearance, an increase in mucous production and eventually asthma. Furthermore, children who experience severe viral respiratory infections early in life have a high possibility of having asthma later in their childhood. These viral respiratory infections are mostly caused by respiratory syncytial virus (RSV) and human rhinovirus (HRV). Although RSV infections increase the risk of asthma in early childhood, the association between asthma and RSV decreases with increasing age. HRV on the other hand is an important cause of bronchiolitis and is strongly associated with asthma development. In children and adults with established asthma, viral upper respiratory tract infections (URIs), especially HRVs infections, can produce acute exacerbations of asthma. Thus, Chlamydia pneumoniae, Mycoplasma pneumoniae and human rhinoviruses are microbes that play a major role in non-atopic asthma.

Mycoplasma penetrans is a species of Gram-positive bacteria. It is pathogenic, though many infected show no symptoms. It is a sexually transmitted disease, though an infant may be infected during birth.

Mycoplasma orale is a small bacterium found in the class Mollicutes. It belongs to the genus Mycoplasma, a well-known group of bacterial parasites that inhabit humans. It also is known to be an opportunistic pathogen in immunocompromised humans. As with other Mycoplasma species, M. orale is not readily treated with many antibiotics due to its lack of a peptidoglycan cell wall. Therefore, this species is relevant to the medical field as physicians face the task of treating patients infected with this microbe. It is characterized by a small physical size, a small genome size, and a limited metabolism. It is also known to frequently contaminate laboratory experiments. This bacteria is very similar physiologically and morphologically to its sister species within the genus Mycoplasma; however, its recent discovery leaves many questions still unanswered about this microbe.

References

  1. 1 2 3 4 5 Hayflick L, Chanock RM (June 1965). "Mycoplasma species of man". Bacteriological Reviews. 29 (2): 185–221. doi:10.1128/mmbr.29.2.185-221.1965. PMC   441270 . PMID   14304038.
  2. 1 2 3 Hayflick, L. (May 1965). "The mycoplasma (PPLO) species of man". Transactions of the New York Academy of Sciences. Series II. 27 (7): 817–827. doi:10.1111/j.2164-0947.1965.tb02241.x. PMID   14333465.
  3. 1 2 Hayflick, L. (1967). Hayflick, L. (ed.). Biology of the mycoplasmas. Second Conference on the Biology of the Mycoplasmas. Vol. 143. Annals of the New York Academy of Sciences. pp. 5–6.
  4. 1 2 3 Hayflick, L., ed. (1969). The Mycoplasmatales and the L-phase of Bacteria. New York, NY: Appleton-Century-Crofts. ISBN   9780608123905.
  5. ↑ Marmion, B.P. (1990). "Eaton agent – science and scientific acceptance: A historical commentary". Reviews of Infectious Diseases. 12 (2): 338–353. doi:10.1093/clinids/12.2.338. PMID   2109871.
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Waites KB, Talkington DF (October 2004). "Mycoplasma pneumoniae and its role as a human pathogen". Clinical Microbiology Reviews. 17 (4): 697–728. doi:10.1128/CMR.17.4.697-728.2004. PMC   523564 . PMID   15489344.
  7. 1 2 Razin S, Hayflick L (March 2010). "Highlights of mycoplasma research – an historical perspective". Biologicals. 38 (2): 183–190. doi:10.1016/j.biologicals.2009.11.008. PMID   20149687.
  8. ↑ Hayflick, L. (1956). The growth of human and poultry pleuropneumonia-like organisms in tissue cultures and in ovo, and the characterization of an infectious agent causing tendovaginitis with arthritis in chickens (Ph.D. thesis). University of Pennsylvania.
  9. ↑ Hayflick L, Stinebring WR (January 1960). "Intracellular growth of pleuropneumonialike organisms (PPLO) in tissue culture and in ovo". Annals of the New York Academy of Sciences. 79 (10): 433–449. Bibcode:1960NYASA..79..433H. doi:10.1111/j.1749-6632.1960.tb42709.x. PMID   14400338. S2CID   21089254.
  10. ↑ Eaton MD, Meiklejohn G, van Herick W (June 1944). "Studies on the etiology of primary atypical pneumonia : A filterable agent transmissible to cotton rats, hamsters, and chick embryos". The Journal of Experimental Medicine. 79 (6): 649–668. doi:10.1084/jem.79.6.649. PMC   2135382 . PMID   19871393.
  11. ↑ Dajani AS, Clyde WA, Denny FW (June 1965). "Experimental infection with Mycoplasma pneumoniae (Eaton's agent)". The Journal of Experimental Medicine. 121 (6): 1071–1086. doi:10.1084/jem.121.6.1071. PMC   2138014 . PMID   14319403.
  12. ↑ Hayflick, L. (1969). "Fundamental biology of the class Mollicutes, order Mycoplasmatales". In Hayflick, L. (ed.). The Mycoplasmatales and the L-phase of Bacteria. New York, NY: Appleton-Century-Crofts. ISBN   9780608123905.
  13. ↑ Hayflick, L. (1971). "Biology of the Mycoplasmatales". In Madoff, S. (ed.). Mycoplasmas and the L-forms of Bacteria. New York, NY: Gordon and Breach. doi:10.1002/jobm.19720120516.
  14. 1 2 3 Hayflick, L. (1965). "Tissue cultures and mycoplasmas". Texas Reports on Biology and Medicine. 23 (1): 285–303. PMID   5833547.
  15. ↑ Hayflick, L. (1966). "The role of mycoplasmas in human disease". The New Physician. December: 328–333, 348–350.
  16. ↑ Hayflick, L. (1972). Mycoplasmas as pathogens. CIBA Foundation Symposium: Pathogenic Mycoplasmas. Amsterdam, NL: Elsevier Excerpta Medica. pp. 17–31.
  17. ↑ Hayflick, L. (4 October 1993). "Isolation and identification of a mycoplasma as the etiological agent of primary atypical pneumonia in humans". Citation Classic. Current Contents. 40: 8.
    Hayflick, L. (April 2013). "The "Eaton agent" and pneumonia". Archives of Environmental Health. 4 (5): 553–554. doi:10.1080/00039896.1962.10663209.
  18. ↑ Chanock RM, Hayflick L, Barile MF (January 1962). "Growth on artificial medium of an agent associated with atypical pneumonia and its identification as a PPLO". Proceedings of the National Academy of Sciences of the United States of America. 48 (1): 41–49. Bibcode:1962PNAS...48...41C. doi: 10.1073/pnas.48.1.41 . PMC   285494 . PMID   13878126.
  19. 1 2 "Robert Chanock and the Eaton Agent". Web of Stories. 8 August 2012.
  20. 1 2 Sharrer, T. (2007). "Leitz inverted microscopes, Circa 1958". The Scientist. 21 (3): 96.
  21. ↑ Klieneberger-Nobel, E. (1980). Memoires (English ed.). London, UK: Academic Press. ISBN   0-12-414850-6.
  22. ↑ Chanock, R.M. (May 1963). "Mycoplasma pneumoniae: Proposed nomenclature for atypical pneumonia organism (Eaton agent)". Science. 140 (3567): 662. Bibcode:1963Sci...140..662C. doi:10.1126/science.140.3567.662. PMID   14020096. S2CID   34513645.
  23. ↑ Edward DG, Freundt EA, Chanock RM, Fabricant J, Hayflick L, Lemcke RM, et al. (March 1967). "Recommendations on nomenclature of the order Mycoplasmatales". Science. 155 (3770): 1694–1696. Bibcode:1967Sci...155.1694E. doi: 10.1126/science.155.3770.1694 . PMID   6020298.
  24. 1 2 3 4 5 Weisburg WG, Tully JG, Rose DL, Petzel JP, Oyaizu H, Yang D, et al. (December 1989). "A phylogenetic analysis of the mycoplasmas: basis for their classification". Journal of Bacteriology. 171 (12): 6455–67. doi:10.1128/jb.171.12.6455-6467.1989. PMC   210534 . PMID   2592342.
  25. 1 2 3 4 5 6 7 8 9 10 11 12 13 Romero-Arroyo CE, Jordan J, Peacock SJ, Willby MJ, Farmer MA, Krause DC (February 1999). "Mycoplasma pneumoniae protein P30 is required for cytadherence and associated with proper cell development". Journal of Bacteriology. 181 (4): 1079–87. doi:10.1128/JB.181.4.1079-1087.1999. PMC   93483 . PMID   9973332.
  26. 1 2 3 Dallo SF, Baseman JB (November 2000). "Intracellular DNA replication and long-term survival of pathogenic mycoplasmas". Microbial Pathogenesis. 29 (5): 301–9. doi:10.1006/mpat.2000.0395. PMID   11031124.
  27. 1 2 3 4 5 6 Wodke JA, Puchałka J, Lluch-Senar M, Marcos J, Yus E, Godinho M, et al. (2013). "Dissecting the energy metabolism in Mycoplasma pneumoniae through genome-scale metabolic modeling". Molecular Systems Biology. 9: 653. doi:10.1038/msb.2013.6. PMC   3658275 . PMID   23549481.
  28. 1 2 3 4 5 6 7 8 9 10 11 12 Yus E, Maier T, Michalodimitrakis K, van Noort V, Yamada T, Chen WH, et al. (November 2009). "Impact of genome reduction on bacterial metabolism and its regulation". Science. 326 (5957): 1263–1268. Bibcode:2009Sci...326.1263Y. doi:10.1126/science.1177263. PMID   19965476. S2CID   17576843.
  29. ↑ Chowdhury S, Hepper S, Lodi MK, Saier MH, Uetz P (April 2021). "The Protein Interactome of Glycolysis in Escherichia coli". Proteomes. 9 (2): 16. doi: 10.3390/proteomes9020016 . PMC   8167557 . PMID   33917325.
  30. ↑ "KEGG PATHWAY: Glycolysis / Gluconeogenesis – Mycoplasma pneumoniae 309". www.genome.jp. Retrieved 2022-10-27.
  31. 1 2 3 Li J, Luu LD, Wang X, Cui X, Huang X, Fu J, et al. (December 2022). "Metabolomic analysis reveals potential biomarkers and the underlying pathogenesis involved in Mycoplasma pneumoniae pneumonia". Emerging Microbes & Infections. 11 (1): 593–605. doi: 10.1080/22221751.2022.2036582 . PMC   8865114 . PMID   35094669.
  32. 1 2 3 4 5 Drasbek M, Christiansen G, Drasbek KR, Holm A, Birkelund S (November 2007). "Interaction between the P1 protein of Mycoplasma pneumoniae and receptors on HEp-2 cells". Microbiology. 153 (Pt 11): 3791–3799. doi: 10.1099/mic.0.2007/010736-0 . PMID   17975088.
  33. 1 2 3 4 5 Baseman JB, Cole RM, Krause DC, Leith DK (September 1982). "Molecular basis for cytadsorption of Mycoplasma pneumoniae". Journal of Bacteriology. 151 (3): 1514–22. doi:10.1128/JB.151.3.1514-1522.1982. PMC   220433 . PMID   6809731.
  34. 1 2 3 Hahn TW, Willby MJ, Krause DC (March 1998). "HMW1 is required for cytadhesin P1 trafficking to the attachment organelle in Mycoplasma pneumoniae". Journal of Bacteriology. 180 (5): 1270–6. doi:10.1128/JB.180.5.1270-1276.1998. PMC   107017 . PMID   9495768.
  35. 1 2 Sobeslavsky O, Prescott B, Chanock RM (September 1968). "Adsorption of Mycoplasma pneumoniae to neuraminic acid receptors of various cells and possible role in virulence". Journal of Bacteriology. 96 (3): 695–705. doi:10.1128/JB.96.3.695-705.1968. PMC   252361 . PMID   4183967.
  36. ↑ "CDC Mycoplasma Pneumoniae". CDC. Retrieved 23 September 2015.
  37. ↑ Großhennig, Stephanie; Ischebeck, Till; Gibhardt, Johannes; Busse, Julia; Feussner, Ivo; Stülke, Jörg (April 2016). "Hydrogen sulfide is a novel potential virulence factor of Mycoplasma pneumoniae : characterization of the unusual cysteine desulfurase/desulfhydrase HapE". Molecular Microbiology. 100 (1): 42–54. doi:10.1111/mmi.13300. ISSN   0950-382X. PMID   26711628.
  38. 1 2 Lanata, Mariana M.; Wang, Huanyu; Everhart, Kathy; Moore-Clingenpeel, Melisa; Ramilo, Octavio; Leber, Amy (June 2021). "Macrolide-Resistant Mycoplasma pneumoniae Infections in Children, Ohio, USA". Emerging Infectious Diseases. 27 (6): 1588–1597. doi:10.3201/eid2706.203206. ISSN   1080-6040. PMC   8153876 . PMID   34013867.
  39. ↑ Cheng, Jie; Liu, Ya; Zhang, Guangli; Tan, Liping; Luo, Zhengxiu (July 2024). "Azithromycin Effectiveness in Children with Mutated Mycoplasma Pneumoniae Pneumonia". Infection and Drug Resistance. 17: 2933–2942. doi: 10.2147/idr.s466994 . ISSN   1178-6973. PMC   11249021 . PMID   39011344.

This article incorporates public domain text from the CDC as cited.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.