Mycoplasma pneumonia is an atypical lung infection, the causative agent of which is Mycoplasma pneumoniae. The disease is accompanied by catarrhal and respiratory manifestations (nasal congestion, sore throat, attacks of obsessive unproductive cough), intoxication syndrome (subfebrility, weakness, headache, myalgia), dyspepsia (discomfort in the gastrointestinal tract). The mycoplasma etiology of pneumonia is confirmed by the data of radiography and CT of the lungs, serological and PCR studies. In disease, macrolides, fluoroquinolones, bronchodilators, expectorants, immunomodulators, physiotherapy, massage are indicated.
J15.7 Pneumonia due to Mycoplasma pneumoniae
Mycoplasma pneumonia is a disease from the group of atypical pneumonia caused by a pathogenic agent – mycoplasma (M. pneumoniae). In the practice of pulmonology, the frequency of pathology varies, ranging from 5 to 50% of cases of community-acquired pneumonia or about a third of non-bacterial pneumonia. The disease is registered in the form of sporadic cases and epidemic outbreaks. Seasonal fluctuations in morbidity with a peak in the autumn-winter period are characteristic. Disease is observed mainly in children, adolescents and young patients under 35 years of age, much less often – in middle and adulthood. Lung infection is more common in organized groups with close contacts (in preschool, school and student groups, in military personnel, etc.), family cases of infection are possible.
Causes of mycoplasma pneumonia
Mycoplasma pneumonia is caused by highly virulent strains of anaerobic microorganisms of the genus Mycoplasma – M. pneumoniae. The pathogen is represented by small (comparable in size to viral particles), having no cell wall (similar to L-forms of bacteria), prokaryotic organisms. Mycoplasmas are easily adsorbed on the surface receptors of target cells (tracheal and bronchial epithelial cells, alveolocytes, erythrocytes, etc.) and parasitize on the membrane or inside the host cell. The integration of mycoplasma into the cell membrane or its penetration into the cell turns the latter into an immunologically foreign one, which provokes the development of autoimmune reactions. It is autoantibody formation that causes non-respiratory manifestations of mycoplasma infection.
Mycoplasmas can persist for a long time in epithelial cells and the lymphopharyngeal ring; they are easily transmitted by airborne droplets from patients and asymptomatic carriers with mucus from the nasopharynx and respiratory tract. Mycoplasmas are not stable in external conditions: they are sensitive to pH drop, heating and drying, ultrasound and UV, do not grow on insufficiently moist nutrient media.
In addition to mycoplasma pneumonia, microorganisms can also cause acute inflammation of the upper respiratory tract (pharyngitis), bronchial asthma, exacerbations of chronic obstructive bronchitis and the development of non-respiratory pathology (pericarditis, otitis, encephalitis, meningitis, hemolytic anemia) in practically healthy people.
The absence of a cell wall provides mycoplasmas with resistance to beta-lactam antibiotics – penicillins, cephalosporins. With mycoplasma infection, the development of local inflammation with a pronounced immunomorphological reaction, local antibody genesis (of all classes of immunoglobulins – IgM, IgA, IgG), activation of cellular immunity is noted. The symptoms of mycoplasma pneumonia are caused mainly by an aggressive inflammatory response of the macroorganism (postinfectious hypersensitivity mediated by T-lymphocytes).
Mycoplasma pneumonia symptoms
The incubation period for mycoplasma pneumonia can last 1-4 weeks (usually 12-14 days). The onset of the disease is usually gradual, but may be subacute or acute. Respiratory, non-respiratory and generalized manifestations of mycoplasma pneumonia are distinguished.
In the initial period, there is a lesion of the upper respiratory tract, which occurs in the form of catarrhal nasopharyngitis, laryngitis, less often acute tracheobronchitis. There is nasal congestion, dryness in the nasopharynx, sore throat, hoarseness of voice. The general condition worsens, the temperature gradually increases to subfebrile values, weakness and sweating appear. In acute cases, symptoms of intoxication occur on the first day of the disease, with gradual development – only for 7-12 days.
A prolonged (at least 10-15 days) unproductive paroxysmal cough is characteristic. During the attack, the cough is very strong, debilitating with the release of a small amount of viscous mucosal sputum. Cough can become chronic, persisting for 4-6 weeks due to airway obstruction and bronchial hyperreactivity. The spectrum of manifestations of mycoplasma pneumonia may include signs of acute interstitial pneumonia.
Of the extrapulmonary symptoms, disease is most characterized by rashes on the skin and eardrums (by the type of acute myringitis), myalgia, discomfort in the gastrointestinal tract, sleep disorder, moderate headache, paresthesia. The addition of non-respiratory manifestations aggravates the course of mycoplasma pneumonia.
Moderate fibrinous or exudative pleurisy may occur, sometimes pleuritic pain. In the presence of concomitant chronic obstruction, mycoplasma pneumonia contributes to the exacerbation of obstructive syndrome. Children under 3 years of age are characterized by a low-symptomatic course.
In uncomplicated cases, the symptoms of this disease gradually disappear within 7-10 days, the disease resolves independently. There is a risk of transition to a mixed (mycoplasma-bacterial) form of pneumonia due to the addition of a secondary infection (usually pneumococcus). Complications of mycoplasma pneumonia are Stevens-Johnson syndrome, Guillain-Barre syndrome, myelitis, encephalitis, meningitis.
Diagnostics of mycoplasma pneumonia
When making a diagnosis of mycoplasma pneumonia, the data of the clinical picture, radiography and CT of the lungs, serological and PCR studies are taken into account. Establishing the etiology in the first week of the disease is difficult due to the initial lack of expression of physical manifestations. Hyperemia of the posterior pharyngeal wall, hypertrophy of the tonsils is noted early, focal weakened vesicular breathing, crepitation, rare medium- and small-bubbly wheezing, shortening of the percussion sound may gradually appear. For mycoplasma pneumonia, the presence of extrapulmonary symptoms is typical.
Lung x-ray show a bilateral strengthening of the pulmonary pattern with heterogeneous, indistinct focal infiltrates typical of pneumonia in the lower segments, in 50% of cases – interstitial changes, peribronchial and perivascular infiltration. Extensive lobar infiltration is rare.
Laboratory shifts – leukocytosis and the rise of ESR in peripheral blood in pneumonia are less pronounced than in patients with bacterial pneumonia. Microbiological examination with isolation of M.pneumoniae culture from sputum, lung tissue and pleural fluid is practically not used, as it requires long incubation periods and highly selective media. With conventional sputum microscopy, mycoplasmas are not detected.
For the etiological verification of pneumonia and the establishment of active and persistent forms of infection, a complex of analyses is carried out, including serotyping (ELISA, RSC, RNIP) and molecular biological examination (PCR). A 4-fold increase in IgA and IgG titers in paired sera is indicative (in the acute stage and during the convalescence period). Mycoplasma pneumonia is characterized by a marked inhibition of the T-cell and phagocytic links of immunity, humoral shifts (an increase in the number of B-lymphocytes, IgM and CEC levels).
ECG changes may occur in patients with the appearance of myocarditis and pericarditis. It is necessary to differentiate mycoplasma pneumonia from acute respiratory viral infections, bacterial pneumonia, ornithosis, legionellosis, pulmonary tuberculosis.
Mycoplasma pneumonia treatment
In acute mycoplasma pneumonia with severe respiratory syndrome, treatment is carried out in a hospital setting. At the time of fever, bed rest is recommended to ensure good aeration of the ward; diet, the use of slightly acidified water, cranberry juice, compotes and juices, infusion of rosehip fruits.
Macrolides, fluoroquinolones and tetracyclines are prescribed as the main eradication therapy for mycoplasma pneumonia. The preference of macrolides is due to safety for newborns, children and pregnant women. It is advisable to conduct step–by-step antibiotic therapy – first (2-3 days) intravenous administration, then oral administration of the same drug or another macrolide.
To prevent the recurrence of mycoplasma pneumonia, the course of antibiotics should last at least 14 days (usually 2-3 weeks). Bronchodilators, expectorants, analgesics and antipyretics, immunomodulators are also indicated. During the convalescence period, non-drug therapy is used: physical therapy, breathing exercises, physiotherapy, massage, hydrotherapy, aerotherapy, spa treatment in dry and warm climates.
Dispensary observation by a pulmonologist for 6 months is indicated for frequently ill patients with chronic diseases of the bronchopulmonary system. The prognosis of mycoplasma pneumonia is usually favorable, the mortality rate can reach 1.4%.
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