mycoplasma & ureaplasma

Mycoplasmas

Mycoplasmas
The family Mycoplasmataceae includes two genera Mycoplasma and Ureaplasma which require cholesterol or other sterols as growth factors. There are many species of genera Mycoplasma and Ureaplasma are known to colonize or cause diseases in human.

Mycoplasmas

The Mycoplasma pneumoniae is the most important species known to cause infection in humans. Mycoplasma hominis, Mycoplasma fermentans, and Mycoplasma genitalium are the other pathogens that are commonly associated with human infections. The genus Ureaplasma includes the organisms that utilize urea. Genus Ureaplasma consists of 5 species of which Ureaplasma urealyticum is the most important species isolatedfrom infections of genital and respiratory tract in humans.

Mycoplasmas

Bacteria
Diseases
Mycoplasma pneumoniae
Upper & lower respiratory tract infection & primary a typical pneumonia.
Mycoplasma hominis
Pelvic inflammatory disease and postpartum fever.
Mycoplasma fermentans
Opportunistic infections in patients with HIV
Mycoplasma pirum
Septicemia in patients with HIV
Mycoplasma genitalium
Infection unknown
Ureaplasma urealyticum
Chorioamnionitis, prematurity, vaginitis, cervicitis, acute sappingitis and pelvic inflammatory disease.

Mycoplasmas

Mycoplasmas are prokaryotes, but they differ from prokaryotes by having a unique cell membrane that contains sterols. Also, the mycoplasmas do not have a cell wall. Mycoplasma pathogens when first discovered were thought to be viruses or L form of bacterea.
Structural features of Mycoplasma.

Mycoplasmas

Properties of the Bacteria:-It is show the following morphological features,Very small bacteria 0.2 – 0.3 µm in diameter to tapered rods of approximately 1 – 2 µm in length and 0.2 - 0.3 in µm diameter. Mycoplasma can pass throught 0.45 µm filtter, hence were once belived to be viruses.But it is differ form viruses in the following propertiesThey contain RND & DNA,They are able to grow on artificial media (in vitro growth),They Show both intracellular & extracellular parasitism in vivo.

Mycoplasmas

Mycoplasma pneumonia
Mycoplasma pneumoniae is the most important species causing upper respiratory tract disease. It is also known for causing walking pneumonia or primary atypical pneumonia. Cell Wall Components and Antigenic Structure: Membrane glycolipids and proteins are the major antigenic determinants of the mycoplasmas. Membrane glycolipid antigens show cross reaction with human tissues and other bacteria. Glycolipids with similar antigenic structure have been demonstrated in neurons in human brain. The antibodies against M. pneumoniae glycolipid may crossreact with brain cell, therefore, causing damage to neuronal cells. This cell damage possibly is responsible for neurological manifestations of M. pneumoniae infection.

Mycoplasma pneumonia

Mycoplasma pneumonia
P1 antigen: P1 antigen is a membrane associated protein, which helps in adhesion of mycoplasmas to epithelial cells. This protein specifically with sialated glycoprotein receptors present at the base of the cilia on epithelial surface. This same receptor is also present on the surface of the erythrocytes. The antibodies against P1 antigen can also act as an autoantibody against RBCs causing their agglutination.



Mycoplasma pneumonia
Epidemiology:- Mycoplasma pneumoniae infection is distributed worldwide, The organism is responsible for up to 20% of community acquired pneumonia, which requires hospitalization. Mycoplasma pneumoniae infection occurs both in epidemic and in endemic forms. M. pneumoniae is a strict human pathogen. The bacteria inhabit the upper respiratory tract in an infected host. Humans are the usual host of M. pneumoniae and thus significant reservoir of infection. M. pneumoniae is most commonly transmitted by close contact through nasal secretions. The infection is transmitted by inhalation of aerosolized droplets. Person to person transmission usually occurs among college students and military recruits who live together in close proximity.

Mycoplasma pneumonia

Mycoplasma pneumonia
Pathogenesis of Mycoplasma infections Following attachment, Mycoplasma cause direct damage to the epithelial cells in which first cilia and then ciliated epithelial cells are destroyed. Loss of the cells interferes with normal functioning of the upper respiratory tract. This results in the lower respiratory tract to become infected with microbes and mechanically irritated. The mechanical irritation causes persistent cough typically seen in patients with respiratory infection caused by M. pneumoniae.

Mycoplasma pneumonia

Pathogenesis of Mycoplasma infections M. pneumoniae behaves as a super antigen. This causes migration of inflammatory cells to the site of infection and produces cytokines, such as tumor necrosis factor alpha, interleukin-1, and interleukin-6. These cytokines help in clearing of the bacteria. The bacteria usually do not cause invasion of the blood to produce systemic manifestation of the disease. M. pneumoniae infection does not induce any protective immunity. Individuals suffering from M. pneumoniae infection are susceptible to reinfection by the bacteria.

Mycoplasma pneumonia

Clinical Syndromes Majority of the respiratory infections are mild and self limiting. M. pneumoniae causes (a) upper respiratory tract infections, (b) lower respiratory tract infections, (c) primary atypical pneumonia.

Mycoplasma pneumonia

Clinical SyndromesUpper respiratory tract infections: M. pneumoniae typically causes mild upper respiratory tract infections.The condition is characterized by low grade fever, malaise, and headache. Nonproductive cough is a typical manifestation, which appears 2–3 weeks after exposure.The cough is initially nonproductive but may later produce small to moderated quantities of sputum, which may become mucopurulent and even blood tinged in more severe cases.

Mycoplasma pneumonia

Clinical Syndromes Lower respiratory tract infections: These include tracheobronchitis and bronchopneumonia. The condition is characterized by primary infection of bronchi with infiltration of bronchial epithelial cells by lymphocytes and plasma cells.

Mycoplasma pneumonia

Clinical Syndromes Primary atypical pneumonia: The condition is also known as walking pneumonia. Incubation period varies from 2 to3 weeks. Patients suffering from atypical pneumonia usually do not appear ill. Hence, the illness is often referred to as walking pneumonia. The pharynx is affected, The condition is associated with presence of patchy bronchopneumonia seen on the chest X ray.

Mycoplasma pneumonia

Laboratory Diagnosis Specimens Respiratory specimens include throat washings, bronchial washings, and expectorated sputum, Tracheal washings are more useful than sputum specimens, because most patients with respiratory tract infections do not produce any sputum as they have a dry and nonproductive cough. The specimens are collected and transported to the laboratory immediately.

Mycoplasma pneumonia

Laboratory Diagnosis Microscopy: Microscopy is of no value in diagnosis of M. pneumoniae infections. Mycoplasmas are stained poorly, because they lack cell wall.

Mycoplasma pneumonia

Laboratory DiagnosisCulture:Bacterial culture is a little practical value because of its fastidious growth requirements and need for 3–4 weeks for culture. Isolation of M. pneumoniae from clinical specimens by culture confirms the diagnosis of M. pneumoniae.The specimens are inoculated into mycoplasma medium, such as PPLO (Pleuropneumonia-like organism) agar supplemented with serum (source for sterols), glucose, pH indicator, yeast extract and antibiotics and antifungal agents (to inhibit bacteria and fungi).On this medium, M. pneumoniae grows very slowly and colonies are demonstrated at 37°C. The growth is facilitated by incubation in the 5% of CO2. The bacteria produce small colonies with homogenous appearance, typically described as mulberry-shaped colonies.

Mycoplasma pneumonia

Laboratory Diagnosis Serodiagnosis Complement fixation test: Enzyme-linked immunosorbent assay:

Mycoplasma pneumonia

Colonies of Mycoplasma pneumoniae visualized under 100X magnification.
Typical large Mycoplasma colony showing fried egg appearance

Mycoplasma pneumonia

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Mixed isolation of Mycoplasma hominis and Ureaplasma urealyticum showing why U. urealyticum was originally called “T” for tiny strain (arrow) (Ч40). Typical chest radiograph of a patient with a 3-week course of atypical pneumonia. Note nonspecific interstitial pneumonia and a patchy infiltrate delineated by a feathery outline.

Mycoplasma pneumonia

Treatment M. pneumoniae is sensitive to Doxycycline (first line) Azithromycin, Levofoxacin
Radiograph of lung of an individual with atypical pneumonia.

GENITAL MYCOPLASMAS

Three Mycoplasma species, Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum. are human urogenital pathogens. They are often associated with sexually transmitted infections, such as NGU (nongonococcal urethritis) or puerperal infections (that is, infections connected with, or occurring during childbirth or the period immediately following childbirth).

GENITAL MYCOPLASMAS

Mycoplasma hominis and Ureaplasma urealyticum are common inhabitants of the GU tract, particularly in sexually active adults. Because colonization rates in some populations are in excess of 50 percent. Both agents can be cultured. They grow more rapidly than M. pneumoniae and can be distinguished by their carbon utilization patterns: M. hominis degrades arginine, whereas U. urealyticum hydrolyses urea. The major clinical condition associated with M. hominis is post-partum or post-abortal fever

GENITAL MYCOPLASMAS

Ureaplasma urealyticum is a common cause of urethritis when neither gonococcus nor chlamydia can be demonstrated, particularly in men.In women, the organism has been isolated from the endometrium of patients with endometritis and from vaginal secretions of women who undergo premature labor or deliver low-birth-weight babies.The infants are often colonized, and Ureaplasma urealyticum has been isolated from the infant’s lower respiratory tract and CNS both with and without evidence of inflammatory response.Treatment:A tetracycline, such as doxycyline, is effective for specific treatment

Diseases caused by M. hominis and U. urealyticum.

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B
The antibiotic used to treat these infections.

Summary of Mycoplasma species. 1- Indicates first-line drugs.