Mycoplasma Pneumoniae

Mycoplasmas are the smallest known bacteria also called as Mollicutes. Mollicutes is derived from two Latin words Mollis and cutes meaning soft body. Mycoplasmas don’t have cell wall, they are wall less bacteria. Their size ranges from to equal to the size of Pox virus. Their key feature is absence of cell wall and due to the absence of cell wall they are naturally resistance to penicillin and other Beta – Lactams. They have cholesterol in plasma membrane. Most of the Mycoplasmas move by gliding movement.

History

in early 1930’s scientists observed some cases of atypical pneumonia. These patients were not having typical symptoms of pneumonia and were not responding to antibiotics used for the treatment of pneumonia. In 1944 Mycoplasma pneumoniae was discovered the agent responsible for causing atypical pneumonia. Mycoplasma pneumoniae is considered as major pathogen of genus Mycoplasma.

Taxonomy

Mycoplasma pneumoniae is an important pathogen of humans and is only present in humans. Its classification is as follows;

Physiology

Mycoplasmas are obligate parasites. They are dependent on external cholesterol source for the synthesis of their plasma membrane. So they need their host for the synthesis of plasma membrane and growth. They are dependent on host for getting most of their compounds. Mycoplasmas are difficult to culture on routine lab growth media. They require especial growth requirements and hence special media for their growth. 5 to 10 % of Carbon dioxide is required for their growth. The incubation period for Mycoplasma pneumoniae is 1 to 4 weeks.

Diseases

Mycoplasma pneumoniae is mainly responsible for causing respiratory disease but it also causes non respiratory problems such as neurological, cardiac, hepatic problems, polyarthritis, erythema multiforme and hemolytic anemia. So it’s diseases are classified as pulmonary and extra pulmonary diseases. In atypical pneumonia there is a presence of dry cough. If let untreated it can cause many further complications too.

Transmission

Mycoplasma pneumoniae spread by aerosols produced by the coughing and sneezing of the infected person. As mycoplasma pneumoniae is present in respiratory tract so when an infected person sneeze or cough, produces small tinny droplets having bacteria present in it. These respiratory droplets are shed into air any person breathing in that air is at a risk of getting mycoplasma pneumoniae infection. Its usual outbreaks are in crowded settings like school, residence halls, nursing homes and hospitals.

Pathology

Mycoplasmaa pneumoniae get attach to lungs due to its pointed ends and attachment proteins present in lungs. Bacteria don’t invade inside the cells it remain attach to mucus membrane and produce hydrogen peroxide which cause ciliary demage and necrosis of mucus membrane. Bacteria produce community acquired respiratory distress syndrome (CARDS) toxin that cause ciliostasis and vacuolation of host cells. It also produce free radicals that causes cytotoxicity. There is an inflammatory response. If the demage occur in bronchi it could result in bronchitis.

Signs and Symptoms

Following are the signs and symptoms associated with atypical pneumonia.

• Mild cough
• Sore throat
• Earache
• Non productive cough without sputum in start.
• Cough on later stages can become productive with sputum white in colour
• Fever
• Anorexia
• Malaise
• Chest pain

The disease is a self-treating disease and gets treated in 10 to 14 days.

Further complications

Following are complications associated with Mycoplasma pneumoniae.

Risk factors

In many people the immune system fight the Mycoplasma pneumoniae and they don’t get a disease. Even if they get it the disease is self treating in 10 to 14 days. The people who are at high risk if getting disease are older adults, childen especially younger than 5 years of age and the persons who are having chemotherapy, immunotherapy or are immunocompromised.

Diagnosis

Mycoplasma pneumoniae can be diagnosed by following ways:

Culturing:

Diagnosis is usually not made by this method as bacteria require 1 week for growing on culture media. After 7 days fried eggs like colonies appear on media.

Serological diagnosis:

Mycoplasma pneumoniae giving cold agglutinin titer of 1:128 or higher represent a recent infection. Cold-agglutinins are IgM auto antibodies against type-O RBCs and they get agglutinate at 4°C. IgM and IgG can be detected after 7-10 days and 3 weeks of infection respectively. Compliment fixation test is also used for diagnosis of Mycoplasma pneumoniae.

Chest X-ray:

Chest X-ray can also be done in Mycoplasma pneumoniae infection but it is non specific one. Mostly there is a patchy consolidation and small pleural effusions can be seen in one or both lungs.

Molecular diagnosis:

The most common and rapid diagnostic test used for Mycoplasma pneumoniae is PCR. Throat swab sample is taken and then PCR for checking the presence or absence of Mycoplasma pneumoniae is done. This test has 78 -100% sensitivity and specificity.

Treatment

Antibiotics are used for treating Mycoplasma pneumoniae infection.

• For children macrolides are first choice including erythromycin, clarithromycin and azithromycin etc.
• For adults antibiotics prescribed are different. Usually used antibiotics are doxycycline, tetracyclines and quinolones such as levofloxacin.

Sometimes corticosteroids are also given along with antibiotics. Immunomodulatory therapy including IV immunoglobulins are also given for better healing and treatment.

Prevention

Following preventive measures can be taken to avoid Mycoplasma pneumoniae infections whose chances are more in the fall and winter months.

• Get a proper sleep and eat a proper diet.
• Avoid contact with people facing Mycoplasma pneumoniae problems.
• Wash your hands after u interact with infected people.
• Wash your hands properly before taking a meal.
• Cover your nose and mouth with a tissue while u sneeze or cough and bin this used tissue.
• If u doesn’t have a tissue don’t cough or sneeze in your hands instead do it in your upper sleeve or elbow. And wash your hands thoroughly after all.
• There is no available vaccine for Mycoplasma pneumoniae.