Mycoplasma pneumonia: what is it, symptoms, treatment, prognosis

What is Mycoplasma Pneumonia?

Mycoplasmapneumonia(lat. Mycoplasma pneumoniae) Is a bacterium that can infect humans. Usually M. pneumoniae causes upper respiratory tract infections, but can also cause pneumonia and is one of the most common causes of SARS. Also, many extrapulmonary infections have been attributed to infections Mycoplasma pneumoniae. However, a causal relationship has not yet been established.

Etiology

Views Mycoplasma Are the smallest living organisms that can survive alone in nature. There are over 120 types mycoplasma; only 13 of these have been isolated from humans, and only four of them are known to cause disease in humans. Mycoplasma pneumoniae Is the pathogen most commonly associated with disease in humans. It is a short stem without a cell wall; therefore it is not visible on Gram stain. It can be isolated on serum-supplemented media. However, this requires special attention and isolation is not usually done in clinical laboratories. It requires special nutrient media and also takes a long time to grow. For these reasons, it is not usually cultivated. It is eliminated from the respiratory tract after many weeks of acute infection; therefore, the body's isolation is not specific to the acute infection at that particular time.

Epidemiology

M. pneumoniae in is currently considered a common cause of community-acquired pneumonia and is spread from person to person through respiratory droplets through close contact. The incubation period is 2 to 3 weeks. Like most respiratory pathogens, infection usually occurs during the winter months, but can occur all year round. It is estimated that about 1% of the population is infected every year. The incidence can be much higher because the infection can be subclinical or cause a milder illness that does not require hospitalization. Outbreaks of mycoplasma infection occur in military recruiting centers, hospitals, nursing homes and other long-term care facilities. Only 5-10% of people infected with mycoplasma develop pneumonia. It causes upper and lower respiratory tract infections in all age groups, especially those between the ages of 5 and 40.

Pathophysiology

M. pneumoniae has adhesive proteins that can attach to epithelial membranes, especially the epithelium of the respiratory tract. After joining M. pneumoniae produces hydrogen peroxide and superoxide, causing damage to epithelial cells and associated cilia. Antibodies produced against M. pneumoniae, can act as autoantibodies as they cross-react with human brain cells and red blood cells. The pathogenesis of Mycoplasma pneumoniae involves the activation of inflammatory cytokines.

Mycoplasma pneumoniae has a sliding motion and specific organelles at the tip that help penetrate between the cilia in the respiratory epithelium, which leads to desquamation of the respiratory epithelium cells. It is believed that prolonged refractory cough occurs due to inhibition of the movement of the cilia.

Mycoplasma pneumoniae causes extrapulmonary disease along with respiratory tract infections, including immune thrombocytopenic purpura, acute hepatitis, autoimmune hemolytic anemia, arthritis and transverse myelitis.

Diagnostics

- History and physical signs.

Many M. pneumoniae infections are asymptomatic. The patient's symptoms are usually more significant than the objective findings of the physical examination. The disease develops gradually, and patients may initially complain of headache, malaise and low-grade fever. A severe cough is usually the most noticeable respiratory symptom. Soreness in the chest when coughing is common. Wheezing may also occur. Other respiratory symptoms include pharyngitis, rhinorrhea and ear pain. Pleural effusion occurs in 15–20% of patients who develop pneumonia and may predict increased morbidity and mortality. Most cases of pneumonia are mild and go away on their own. However, a faster current may also occur. Extrapulmonary signs can help suggest a diagnosis and include hemolysis, skin rash, joint pain, gastrointestinal (GI) symptoms, and heart diseases. This occurs in less than 5-10% of patients. Hemolysis occurs due to IgM antibodies that trigger a cold agglutinin reaction. Heart damage includes conduction abnormalities on the ECG, congestive heart failure and chest pain.

Physical examination results are often minimal. Chest auscultation may be normal even if pneumonia is present. Scattered wheezing, whistling sounds may appear later in the course of the disease. Sinus tenderness and mild erythema the back of the pharynx can also be detected by physical examination. A mild erythematous maculopapular or vesicular rash may also be found. In some cases, you can see myringitis bullous, the presence of vesicles or bullae on the eardrum.

- Analysis and visualization.

There is no specific clinical or radiological evidence for mycoplasma pneumonia to distinguish it from other causes of SARS. However, patients usually have a more gradual onset of the disease, more pronounced multisystem involvement, and a normal white blood cell count. Patients are usually on an outpatient basis and microbial diagnostics are usually not performed outpatients with community-acquired pneumonia, since empiric treatment is usually successful. Whenever possible, PCR can be performed quickly and this is the assay of choice. The cold agglutinin test can sometimes be used to confirm a clinical diagnosis when a quick diagnosis is needed.

M. pneumoniae does not have a cell wall and is finicky; therefore Gram stain and culture are not suitable for diagnosing these organisms. Mycoplasma pneumoniae is difficult to cultivate; special nutrient media and 7-21 days of cultivation. Serologic tests such as complement fixation, enzyme immunoassay, immunochromatography and hemagglutination have acceptable sensitivity and specificity. Those serologic tests that show a four-fold increase or decrease in paired sera or single splint titers greater than 1:32 are diagnostic for Mycoplasma pneumoniae.

Hemolysis is found in most patients with pneumonia and causes a positive Coombs' result and an increase in reticulocyte count. Titers of cold agglutinins are increased in more than 50% of patients with mycoplasma disease. However, it is not specific for Mycoplasma infections and can be found in patients with viral pneumonia or infectious mononucleosiscaused by Epstein-Barr virus or cytomegalovirus infection. The number of leukocytes is normal in 75–90% of cases. The most common chest x-ray findings are reticulonodular structures or consolidation patches; they can be unilateral or bilateral and are more pronounced in the lower lobes.

It was found that the level of cationic protein of eosinophils is increased in patients with mycoplasma infection and asthma. This protein is believed to damage the epithelium of the airways and cause hypersensitivity of bronchial smooth muscle. However, more research is needed before its use as a diagnostic marker becomes universal.

- Differential diagnosis.

M.pneumoniae is a very common cause of community-acquired pneumonia in healthy people under the age of 40. Major outbreaks are known to occur in the late summer months and early fall. The infection is also more common in people living in the immediate vicinity, such as prisoners and military personnel. Unlike other viral pneumonias, the incubation period for mycoplasma is 14-21 days. The key diagnostic feature is the absence of a wet cough. Other diagnoses that can be confused with mycoplasma pneumonia include the following:

• aspiration pneumonia and pneumonitis;
• bacterial pneumonia;
• chlamydial pneumonia;
• Coxiella burnetii infection;
• empyema;
• legionnaires disease;
• lung abscess;
• childhood pneumonia;
• k-fever;
• viral pneumonia.

Treatment

The gradual onset of symptoms in combination with extrapulmonary involvement and a normal white blood cell count indicates SARS. Most patients with pneumonia caused by M. pneumoniae, are on an outpatient basis, and empiric antibiotics are often used to treat SARS. Note that many patients may go through a period of symptomatic treatment before seeking medical attention and / or receiving antibiotic treatment.

Treatment M. pneumoniae includes macrolides, doxycycline, or fluoroquinolones. Azithromycin is the most commonly used antibiotic and is usually given over 5 days (500 mg for the first dose, then 250 mg daily for 4 days). Patients receiving doxycycline or fluoroquinolones should be prescribed a course of treatment for 7 to 14 days. Macrolide resistance continues to grow, so if the patient does not respond to macrolides, other antibiotics may be prescribed. Routine antibiotic prophylaxis is not required for those who come into contact with them, except for those who are predisposed to serious mycoplasma infection, for example, patients with sickle cell anemia or antibody deficiency. For prevention, doxycycline or macrolides are used.

Forecast

Most patients who receive timely treatment have an excellent prognosis and patients are expected to make a full recovery. Symptoms and signs of pneumonia usually resolve within a few days without any complications. However, in young children, infection can be associated with severe pneumonia and in patients with sickle cell disease, with acute chest syndrome. Immunity after infection with Mycoplasma pneumoniae is short-lived.

Complications

Although mycoplasma pneumoniae is a benign infection in most people, it can lead to a number of complications, especially in children and the elderly. The list of complications included the following:

• acute respiratory distress syndrome;
• obliterating bronchiolitis;
• lobar compaction syndrome of the lung tissue;
• lung abscess;
• necrotizing pneumonitis;
• pleural effusion (15% to 20%), empyema (rare);
• breathing disorder.

—​ Extrapulmonary complications.

Mycoplasma can also be associated with severe extrapulmonary complications. These complications can be caused by the body itself or by an immunological reaction to bacteria. The list of extrapulmonary complications includes:

• Myocardial problems: conduction disturbances, heart block, or rhythm disturbances. Young people are registered as pericarditisand stagnant heart failure.
• Central nervous system (CNS): rare, but may include encephalitis, transverse myelitis, aseptic meningitis and cerebellar ataxia. These CNS complications are more common in children.
• Hematologic problems: Haemolytic anemia occurs due to cross-reactivity of antibodies to antigens M. Pneumoniae to erythrocytes. Light hemolysis.
• Dermatology: infection M. Pneumoniae may be related to hives, erythema nodosum, or Steven Johnson syndrome. Skin lesions occur in about a third of patients.
• Musculoskeletal problems include myalgia and arthralgia. Septic arthritis is very rare. Rare cases of rhabdomyolysis have been reported.
• Gastrointestinal (GI) tract dysfunction includes pancreatitis or hepatitis and is associated with circulating IgM antibodies.
• Ophthalmic problems include conjunctivitis, papillitis of the optic nerve, anterior uveitis and cranial nerve neuropathy.
• Kidney problems are rare and can lead to glomerulonephritis as a result of the deposition of immune complexes in the glomeruli.