Mycoplasmosis (mycoplasma infection): diagnosis

Clinical diagnosis of M. Pneumoniae infection suggests ORZ or pneumonia, in some cases and its possible etiology. The final etiologic diagnosis is possible with the use of specific laboratory methods.

Clinical signs of pneumonia of mycoplasmal etiology:

• subacute onset of respiratory syndrome (tracheobronchitis, nasopharyngitis, laryngitis);
• subfebrile body temperature;
• unproductive, painful cough;
• sputum smear;
• scanty auscultative data;
• extrapulmonary manifestations: cutaneous, articular (arthralgia), hematological, gastroenterological (diarrhea), neurological (headache) and others.

In case of acute respiratory illness caused by M. Pneumoniae, the picture of blood is not informative. With pneumonia, the majority of patients have normal leukocyte count, 10-25% of cases, leukocytosis up to 10-20 thousand, leukopenia is possible. In the leukocyte formula, the number of lymphocytes is increased, the stab-shift shift is rarely observed.

Radiological examination of the chest organs is of great importance for diagnosis.

With M. Pneumoniae-pneumonia, both typical pneumonic infiltrations and interstitial changes are possible. The radiological picture can be very variable. Often there is bilateral damage to the lungs with increased pulmonary pattern and peribronchial infiltration. Characteristic are the enlargement of the shadows of large vascular trunks and the enrichment of the pulmonary pattern with small linear and loopy details. The enhancement of the pulmonary pattern may be limited or widespread.

Infiltrative changes are diverse: spotty, heterogeneous and inhomogeneous, without clear boundaries. Localized usually in one of the lower shares, involving one or more segments in the process; Possible focal and drainage infiltration in the projection of several segments or lobes of the lung. With infiltration, an exciting fraction of the lung, differentiation is difficult with pneumococcal pneumonia. Possible bilateral defeat, infiltration in the upper lobe, atelectasis, involvement in the pleura process both in the form of dry pleurisy, and with the appearance of a small effusion, interlobite.

Mycoplasma pneumonia has a tendency to protracted development of inflammatory infiltrates. Approximately 20% of patients have radiological changes for about a month.

In the smear of patients with pneumonia, a large number of mononuclear cells and a certain amount of granulocytes are detected. Some patients have purulent sputum with a large number of polymorphonuclear leukocytes. Mycoplasmas are not detected with sputum smear microscopy, Gram stained.

In the specific laboratory diagnosis of M. Pneumonia infection, it is preferable to use several methods. When interpreting the results, it should be borne in mind that M. Pneumoniae is capable of persistence and its isolation is an ambiguous confirmation of acute infection. It should also be remembered that the antigenic relationship of M. Pneumoniae to human tissues can both provoke autoimmune reactions and cause false positive results in various serological studies.

The culture method is of little use for the diagnosis of M. Pneumoniae infection, since for the isolation of the pathogen (from sputum, pleural fluid, pulmonary tissue, flushing from the posterior pharyngeal wall) special media are required and for colonies it takes 7-14 days or more.

More important for diagnosis are methods based on the detection of M. Pneumoniae antigens or specific antibodies to them.

The RIF allows detecting mycoplasma antigens in smears from the pharyngeal nasopharynx and other clinical material. The M. Pneumoniae antigen can also be detected in serum by the IFA method. Determination of specific antibodies using DSC, NRAF. EIA, RIGA. The most frequently used ELISA and / or NERIF for the detection of IgM-, IgA-, IgG-antibodies. Diagnostic significance is the growth of titres of IgA and IgG antibodies by four times or more when tested in paired sera and high titers of IgM antibodies. It should be remembered that some tests do not distinguish between M. Pneumoniae and M. Genitalium.

Determination of the genetic material of the pathogen by the PCR method is currently one of the most common methods for diagnosing mycoplasma infection.

One of the recommended schemes for the diagnosis of M. Pneumonia infection is the determination of the DNA of the pathogen by the PCR method in the material from the nasopharynx in combination with the determination of antibodies by ELISA.

The diagnostic minimum of the examination corresponds to the procedure for the examination of patients with community-acquired pneumonia, which is performed on an outpatient basis and / or in a stationary setting. The specific laboratory diagnosis of M. Pepitonia infection is not included in the mandatory list, but it is desirable to carry out it if suspected of atypical pneumonia and the corresponding diagnostic capabilities. In acute respiratory disease it is not mandatory, it is performed on clinical and / or epidemiological indications.

Differential diagnostics

Pathognomonic clinical symptoms that make it possible to distinguish acute respiratory disease of mycoplasmal etiology from other ARI are not revealed. Etiology can be clarified by conducting specific laboratory studies; it is important for an epidemiological investigation, but it does not determine the significance for the treatment.

Differential diagnostics between ORZ and mycoplasmal pneumonia is actual. Up to 30-40% of mycoplasmal pneumonia during the first week of illness are estimated as ARI or bronchitis.

Clinico-radiologic picture of community-acquired pneumonia in many cases does not allow to express with certainty in favor of the "typical" or "atypical" nature of the process. At the time of the choice of antibacterial therapy, the data of specific laboratory studies, which allow to establish the etiology of pneumonia, are inaccessible in the overwhelming majority of cases. At the same time, given the differences in the choice of antimicrobial therapy for "typical" and "atypical" community-acquired pneumonia, it is necessary to evaluate the available clinical, epidemiological, laboratory and instrumental data to determine the possible nature of the process.

Primary atypical pneumonia, in addition to M. Pneumoniae, is pneumonia associated with ornithosis. C. Pneumoniae infection. ku-fever, legionellosis, tularemia, whooping cough, adenovirus infection, influenza, parainfluenza. Respiratory syncytial viral infection. To exclude ornithosis. Ku-fever, tularemia is often informative epidemiological anamnesis. In sporadic cases of legionellosis, the radiographic and clinical picture may be identical to M. Pneumoniae pneumonia, and differential diagnosis} - can only be performed using laboratory data.

Infiltration in the upper lobe of the lung in association with sputum with blood veins makes it necessary to exclude tuberculosis.

Indications for consultation of other specialists

Indication for consultation of other specialists is the occurrence of extrapulmonary manifestations of M. Pneumoniae infection.

Indications for hospitalization

Hospitalization with respiratory mycoplasmosis is not always required. Indications for hospitalization:

• clinical (severe course of the disease, burdened premorbid background, ineffectiveness of starting antibacterial therapy);
• social (impossibility of adequate care and fulfillment of medical appointments at home, the desire of the patient and / or members of his family);
• epidemiological (persons from organized collectives, for example barracks).

[1], [2], [3], [4], [5]