Mycoplasma pneumoniae is one of the bacteria. Among other things, the germ causes atypical pneumonia.

What is Mycoplasma pneumoniae?

The bacterium Mycoplasma pneumoniae belongs to the family Mycoplasmataceae. It causes various diseases, including atypical pneumonia. Similarly, a middle ear infection, inflammation of the larynx, a tracheobronchitis or meningitis can be caused by the pathogen.

For a long time, doctors and scientists concerned with atypical pneumonia were unaware that Mycoplasma pneumoniae was a bacterium. Thus, the mycoplasmas did not reach the size that was necessary for their visualization at the time. Also bacterial filters had no effect on the germs. For this reason, Mycoplasma pneumoniae at that time received the name "Eaton's Agent".

Occurrence, distribution & characteristics

Mycoplasma pneumoniae occurs only in humans and is found all over the world. The transmission of the bacterium takes place by droplet infection. Therefore, the germ spreads especially in places where there is active contact with patients. These may be schools, kindergartens, children's homes, military facilities or shared flats. Particularly affected by an infection with Mycoplasma pneumoniae are children between the ages of 5 and 15 years.

With an average size of 0.1 to 0.6 microns Mycoplasma pneumoniae belongs to the smaller bacteria. The germ is equipped with both DNA and RNA. Although the mycoplasmas are generally considered to be flexible, their osmotic resistance is deficient. Because they are not equipped with a cell wall, they can not be recognized by a Gram stain.

Likewise, treatments with beta-lactam antibiotics are unsuccessful. These only have an effect on bacteria that have a cell wall and murein layer. Also ineffective is the enzyme lysozyme, which occurs in the endosome. Normally, the lysozyme attacks the cell wall of the bacteria, which leads to their destruction.

Mycoplasma pneumoniae has an altered metabolism, which is why it is no cholesterol synthesis possible. For their growth, therefore, the bacteria need cholesterol from the host cell. Furthermore, the pathogen is equipped with special surface molecules. Although these are not pili, they may function as cytoadhesins for attachment to the respiratory epithelium. There are pathogenicity factors such as special super-antigens. These are B- and T-cell mitogens, from which cell division is induced. In addition, oxygen radicals form, causing epithelial damage.

Due to their flexible outer shape, the mycoplasmas are able to penetrate filters that bacteria usually can not pass. In a laboratory it is possible to grow Mycoplasma pneumoniae. After about two to eight days, the germ produces a so-called fried egg colony.

Mycoplasma pneumoniae is considered highly contagious. Within the human body, the bacterium acts like a parasite and attaches to the epithelial cells of the lungs, which are called cilia. Through certain protein structures, the mycoplasma attaches to the mobile cilia and slides down their roots. At this point, the propagation of the pathogen begins.

Mycoplasma pneumoniae produces H2O2 (hydrogen peroxide). As the hydrogen peroxide penetrates into the cells of the ciliated epithelium, it can damage them. For this reason, mucous and other substances are removed only insufficiently from the lungs. In addition, the mycoplasmas make the work of the human body's defense system harder and more protec- tive. In this way, a longer survival of the germs is possible. Furthermore, Mycoplasma pneumoniae procures missing nutrients from the cilia.

Diseases & complaints

Mycoplasma pneumoniae is not found in healthy people, yet it can easily be transmitted, causing different diseases. Children in particular often suffer from atypical or interstitial pneumonia. In most cases, however, it only causes a slight sore throat. A diagnosis therefore usually remains off.

After infection with Mycoplasma pneumoniae, it takes about 10 to 20 days for the first symptoms to start. These include primarily agonizing cough with little expectoration, fever and headache, with symptoms progressing only slowly.

In the further course there is the risk that an atypical pneumonia arises. In contrast to conventional pneumonia, when listening to and tapping the chest, the doctor can not hear any sounds otherwise heard in pneumonia. In some cases, however, only slight or even no complaints appear.

In addition to the atypical pneumonia Mycoplasma pneumoniae causes other diseases. These are haemolytic anemia, tracheobronchitis, pharyngitis (pharyngitis), muscle pain and maculopapillary erythema.

Likewise, some severe neurological diseases can occur. Physicians also suggest that there is a link between mycoplasma pneumoniae infection and bronchial asthma.

To detect Mycoplasma pneumoniae in the patient's body, material is recovered from the sputum or tracheal secretions. In addition, antibodies can be detected by ELISA or a complement fixation reaction (CBR).

Diseases caused by Mycoplasma pneumoniae are usually treated by the administration of tetracyclines such as doxycycline. Children usually get macrolides like erythromycin. In contrast, cephalosporins or penicillin are not suitable for treatment because the mycoplasmas are not equipped with a cell wall.

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