Mycoplasma vs Mycobacterium

Mycobacteria are aerobic and slender, curved rod shaped species. Since they are aerobic they like to live in areas where oxygen levels are high; such as, apical or upper part of the lungs. Thus, a decrease in oxygen concentration can be dangerous for these organisms. On the other hand, Mycoplasma is a bacterial genus that has more than 100 species. It was first described in the late 1800s and members of this genus are very tiny. Even though most of the species of this genus are harmless, there are some that appear to be virulent and thus are responsible for “specific medial conditions in humans” (1).

Mycobacteria cell wall is composed of waxes and mycolic acids, which makes them resistant to Gram staining; however, they can be stained acid-fast. Whereas, Mycoplasmas are gram negative bacteria and one interesting characteristic of these bacteria is that they don’t have a cell wall; which gives them an elastic shape that can vary easily (1). The unusual cell wall of Mycobacterium and the absence of cell wall in Mycoplasmas make them invulnerable to many drugs. Plus, both, Mycobacterium and Mycoplasma, grow very slow, this also accounts for the long time to make observable colonies on laboratory media.

Both Mycobacterium tuberculosis and Mycoplasma pneumoniae are pathogenic bacterial species that causes respiratory tract disease. The disease that Mycobacterium tuberculosis cause is called tuberculosis and Mycoplasma pneumoniae are responsible for causing mild upper respiratory tract infection known as atypical pneumonia. Mycobacterium tuberculosis was first discovered in 1882 by Robert Koch and it belongs to the genus Mycobacterium; whereas, Mycoplasma pneumoniae belong to genus Mycoplasma. Atypical pneumonia symptoms are different from typical pneumonia. In addition, sometimes patients don’t even have any symptoms related to the respiratory tract. Frequently, patients remain ambulatory, therefore this condition is also sometimes called walking pneumonia.

Tuberculosis (TB) is spread from person to person via air. If a person, who has TB, coughs, sneezes, or speaks, he can put M. tuberculosis into the air. If nearby people breathe in these bacteria they can become infected. On the other hand, Mycoplasma pneumoniae is also transmitted from one person to another through close personal contact by respiratory droplets. Symptoms, such as fever, chest pain and cough, can be seen after the organism is in the host’s system for 12 to 14 days. Common characteristics of walking pneumonia are that the size of alveoli is decreased due to inward swelling of the alveolar walls and alveoli don’t fill with fluid.

Whereas a typical pathogenesis for tuberculosis is that once the bacteria are inhaled, they start dividing at a very slow pace inside the cells (white blood cells) that have phagocytized them. They then educe a host response such as infiltration of neutrophil and accumulation of fluid in the alveoli of the lung. The neutrophils are ruptured and destroyed by the organisms. Then, macrophages and lymphocytes come to the alveoli and phagocytize living tubercle bacilli. These organisms again divide within the new host cell and destroy it; as the phagocytes rupture they release infective organisms. This process goes on until enough cells have been ruptured and an acute inflammatory response has occurred. If lesions are not healed, they can result in tissue necrosis or harden to become chronic granulomas, also known as tubercles. These tubercles may contain live tubercle bacilli or macrophages, and lung tissues and function in these areas are permanently destroyed. Also, some tubercle bacilli can also enter lymphatic and circulatory system. They spread through the body and form numerous lesions; this condition is called military tuberculosis

Tuberculosis and walking pneumonia can be diagnosed in a clinical sample such as sputum; however, since the bacteria grow very slowly sputum culturing process can take weeks before it is declared negative. Other options for diagnosis of tuberculosis are X-rays or skin test and for walking pneumonia other serologic tests are ELISA, indirect immunofluorescence, etc. But usually treatment is given based on clinical symptoms.

Mycoplasma pneumoniae don’t possess a cell wall which results in osmotic instability, so they utilize sterol in their membrane for structural support. However, survival without a cell wall is not a problem for these organisms, because they live in an animal (human) host, which is osmotically stable (2). M. pneumoniae are invulnerable to B-lactam antibiotics, such as penicillin, because they disturb the cell wall and these microorganisms don’t have a cell wall (2). So drugs, such as azithromycine or fluroquinolone, are used to fight these microorganisms. On the other hand, Mycobacteria unusual cell wall hinders the access of drugs and makes many antibiotics ineffective. However, drugs such as isoniazid and rifampicin can be given to the patients for at least one year. In addition, bacillus of Calmette and Guérin (BCG) vaccine is world-widely used to prevent tuberculosis, but there is no vaccine currently available for walking pneumonia. Thus to prevent atypical pneumonia close contact with infected people is avoided.

Mycoplasma pneumoniae is one of the smallest bacterial pathogen from the genus Mycoplasma. This microorganism is responsible for causing mild upper respiratory tract infection known as atypical pneumonia. This type of pneumonia has symptoms that are different from the typical pneumonia. In addition, sometimes patients don’t even have any symptoms related to the respiratory tract. Frequently, patients remain ambulatory, therefore this condition is also sometimes called walking pneumonia.

Mycoplasma pneumoniae is transmitted from one person to another via respiratory droplets. Symptoms, such as fever, chest pain and cough, can be seen after the organism is in the host’s system for 12 to 14 days. Common characteristics of walking pneumonia are that the size of alveoli is decreased due to inward swelling of the alveolar walls and alveoli don’t fill with fluid. Atypical pneumonia is diagnosed “by isolating M. pneumoniae from sputum or from a nasopharyngeal swab”; however, since these bacteria grow very slowly this process can take up to 3 weeks. There are other serologic tests such as ELISA, indirect immunofluorescence, etc., but usually treatment is given based on clinical symptoms.

These microorganisms don’t possess a cell wall which results in osmotic instability, so they utilize sterol in their membrane for structural support. However, survival without a cell wall is not a problem for these organisms, because they live in an animal (human) host, which is osmotically stable (2). M. pneumoniae are invulnerable to B-lactam antibiotics, such as penicillin, because they disturb the cell wall and these microorganisms don’t have a cell wall (2). So drugs, such as azithromycine or fluroquinolone, are used to fight these microorganisms. Plus, currently there is no vaccine available, thus to prevent atypical pneumonia avoid close contact with infected people.

References

“What is Mycoplasma?” WiseGEEK: clear answers for common questions. Web. 16 Feb. 2010. <http://www.wisegeek.com/what-is-mycoplasma.htm>.

“M. pneumoniae.” Index of /. Web. 17 Feb. 2010. <http://s99.middlebury.edu/BI330A/projects/Howard/Mpneumoniae.html>.