Mycoplasma pneumonia in the elderly

Introduction to mycoplasmal pneumonia in the elderly Mycoplasma pneumonia is an acute respiratory infection caused by Mycoplasma pneumoniae with pneumonia. Mycoplasma pneumoniae is between viruses and bacteria. It grows on cell-free medium, has no cell wall, contains RNA and DNA, and is metabolized to produce energy, often with bacteria. The L-forms are confused and the colonies of the two are similar. Mycoplasma is the causative agent of various diseases of animals. Currently, there are 8 kinds of human mycoplasma. Only Mycoplasma pneumoniae can cause respiratory infections. It can ferment glucose and produce hemolysin. It can completely dissolve sheep and guinea pigs within 24 to 48 hours. The red blood cells can be distinguished from other mycoplasmas. Other mycoplasma can cause genitourinary infections, generally do not invade the respiratory tract. Mycoplasma pneumoniae often causes upper respiratory tract infections without pneumonia, and can also cause asymptomatic infections. Reports at home and abroad have shown that the incidence of mycoplasmal pneumonia has increased significantly in recent years. basic knowledge The proportion of illness: the probability of illness in the elderly is 1.7% Susceptible people: the elderly Mode of infection: non-infectious Complications: Meningitis, polyneuritis, epilepsy, autoimmune hemolytic anemia, thrombocytopenic purpura, pericardial effusion, arrhythmia, diarrhea, sinusitis, hyponatremia, disturbance of consciousness

The cause of mycoplasmal pneumonia in the elderly

Causes:

Mycoplasma pneumoniae is a facultative anaerobic, minimal microorganism capable of living independently. It is 200 nm in size and has a sterile cell wall. It can grow and divide and multiply on cell-free medium. It contains RNA and DNA, which is metabolized to produce energy and is sensitive to antibiotics. Mycoplasma is the causative agent of various diseases of animals. At present, eight types have been discovered. Among them, only Mycoplasma pneumoniae is definitely causing disease to humans, mainly respiratory diseases, and grows well on agar medium of 20% horse serum and yeast. The typical cultured under the microscope can be seen as a typical dome-shaped mulberry-like colony. After repeated passages, it is transformed into an omelet shape. Mycoplasma ferments glucose, which has a hemadsorption effect, dissolves guinea pigs, sheep red blood cells, and methylene blue. Barium acetate, penicillin and other resistance, and finally need to be serum identification, it is transmitted by the mouth, nasal secretions through the air, causing sporadic and small epidemic respiratory infections, mainly in winter, respiratory infections have pharyngitis and bronchitis, a few Involved in the lungs, mycoplasmal pneumonia accounts for more than 1/3 of non-bacterial pneumonia, or 10% of various pneumonia.

Pathogenesis:

Mycoplasma pneumoniae can be found in respiratory secretions from 2 to 3 days before onset of mycoplasmal pneumonia until several weeks after the onset of pneumonia. After invading the alveoli, M. pneumoniae usually exists between the ciliated epithelium and does not invade the alveolar cells. Receptor site, adsorbed on the surface of host respiratory tract epithelial cells, inhibits cilia activity and destruction of epithelial cells, and submucosal cell infiltration through the production of peroxides, the pathogenesis of intrapulmonary and extrapulmonary organ lesions caused by Mycoplasma pneumoniae It is not fully understood that some people believe that the pathogenicity of Mycoplasma pneumoniae may be related to the patient's allergic reaction to pathogens and their metabolites. It is a hyperimmune response of the host to infection. The occurrence of extrapulmonary organ lesions may cause an immune response after infection. The production of immune complexes is related to autoantibodies, but it has also been reported that Mycoplasma pneumoniae can directly invade the central nervous system and heart through lymphatic and blood flow, thereby causing meningitis and myocardial pericarditis, and the lung lesions are flaky or fusion bronchus. Inflammation, interstitial pneumonia, bronchial pneumonia, a small amount of osmosis in the alveoli Fluid and septal atelectasis, alveolar wall and septa often have neutrophil and mononuclear cell infiltration, mucosal congestion, epithelial cell swelling, cytoplasmic cavity formation, pleural fibrin exudative inflammation, In the central nervous system, meningitis, encephalitis and myelitis lesions can be seen. Patients with heart disease can see myocardium and pericardial inflammation. Autopsy reports embolism after multiple intravascular thrombosis.

Elderly mycoplasma pneumonia prevention

With aging, the body's physiological structure and function change, the elderly tend to be prone to pneumonia and lead to death, including changes in cough reflexes, spine curvature, etc., plus other such as severe hypoxemia, Pulmonary edema, acidosis, and azotemia all increase the susceptibility to pneumonia. Changes in the defense function of the elderly include increased secretion of mucus in the lung tissue, decreased ciliary movement, decreased phagocytic activity of polymorphonuclear leukocytes, and T associated with ageing. Significant lack of cell function, these have created an opportunity for the invasion of microorganisms. In recent years, the infection of Mycoplasma pneumoniae in the elderly has gradually increased, especially for the elderly with the above risk factors, such as chronic heart, lung, liver and kidney. Elderly patients with such diseases as well as long-term use of hormones, immunosuppressive agents, advanced cancer, diabetes patients to carry out health education, avoid contact with pneumonia patients, can reduce the chance of infection, during the epidemic of pneumonia mycoplasma pneumonia, to maintain indoor air circulation, timing Boil vinegar for room air disinfection, less to public places, insist on forging Refining the body, improving immunity, and paying attention to the seasonal changes in the onset of pneumonia, especially in elderly patients with COPD. Once you suspect that you have mycoplasmal pneumonia, you should go to the hospital for further examination to confirm the diagnosis.

Elderly patients with mycoplasmal pneumonia Complications meningitis polyneuritis epilepsy autoimmune hemolytic anemia thrombocytopenic purpura pericardial effusion arrhythmia diarrhea sinusitis hyponatremia dysfunction

Extrapulmonary complications are mainly:

1 nervous system: central and peripheral neuropathy, can occur 4 weeks after infection, manifested as aseptic meningitis (often shorter), meningoencephalitis, polyneuritis, severe cases may have transverse myelitis Seizures and even mental disorders, but rarely cause death.

2 blood system: occurs 2 to 3 weeks after onset, mainly autoimmune hemolytic anemia, thrombocytopenic purpura, diffuse intravascular coagulation.

3 cardiovascular system: lighter only manifested as abnormal ECG, severe cases can occur pericardial effusion, cardiac insufficiency and arrhythmia.

4 exercise system: specific muscle pain and joint pain can occur within 2 weeks of onset, mainly with large and medium joints, multiple joints, migratory, slow relief, visible erythema multiforme.

5 other: gastrointestinal symptoms: loss of appetite, nausea, vomiting, diarrhea, etc.; ulcerative stomatitis; conjunctivitis and sinusitis, for elderly patients can have a variety of atypical manifestations, fever is generally low fever, high fever Cold war is rare. In some cases, the body temperature is not high. Symptoms are mainly manifestation of weakness, loss of consciousness and loss of appetite, often accompanied by electrolyte imbalance, especially in patients with poor diet, common hypokalemia and hyponatremia.

Symptoms of mycoplasmal pneumonia in the elderly Common symptoms Weak appetite, fever, purulent sputum, nausea, appetite, chest pain, nasal congestion, dry cough, body discomfort

Symptom

The onset of the disease is slow, the incubation period is generally 2 to 3 weeks, about 1/3 of the cases are asymptomatic, the initial symptoms are similar to the symptoms of upper respiratory tract infection, some cases of trachea, bronchitis and pneumonia, some in the form of tympanitis Appeared, and the most serious pneumonia, about one-third of the members of the family developed pneumonia, about 1/2 for bronchitis, 10% for pharyngitis, often chills, fever, body temperature at 38 ~ 39 ° C, Accompanied by cough, sore throat, headache, fatigue, general malaise, etc., persistent paroxysmal cough is its outstanding performance, no sputum or only a small amount of mucous sputum, no hemoptysis, but occasionally sputum with blood, sternum Post- and two-season rib pain, lasting for several weeks, without dyspnea and difficulty breathing; may have digestive symptoms, loss of appetite, nausea, vomiting, diarrhea, etc.; a small number of patients may have migratory joint pain, polymorphism Erythema, ulcerative stomatitis, conjunctivitis and sinusitis, fever can last for 2 to 3 weeks, after the heat returns to normal, there may be cough for about 6 weeks, accompanied by obvious fatigue, burnout, and a few cases may have extrapulmonary complications. Can involve any organ, sometimes more than pneumonia itself Heavy resistance in clinical easily overlooked and misdiagnosed.

2. Signs

Visible nasal congestion, runny nose, pharyngeal congestion, ear tympanic membrane congestion, edema, about 15% for tympanitis, cervical lymph nodes can be swollen, visible polymorphic rash, a few cases have maculopapular rash, erythema or cold sore, no chest Signs or only a few wet voices, especially in elderly patients, signs are particularly atypical, 10% to 15% of cases with a small amount of pleural effusion or pleural friction sound.

Examination of mycoplasmal pneumonia in the elderly

Acute blood routine examination showed that the total number of white blood cells was normal or slightly elevated, mainly lymphocytes; occasionally leukemia-like reaction or leukopenia, erythrocyte sedimentation rate increased in about 2/3 cases (>40mm/h); urine Laboratory tests for normal or a small amount of proteinuria; liver function tests may also have elevated transaminase; pleural effusion is serous or serous, protein 32 ~ 49g / L, in the cytosol has been isolated from mycoplasma.

1. Pathogen examination can be used to isolate and culture specimens of Mycoplasma pneumoniae from pharyngeal secretions (throat swab, pharyngeal wash), bronchoalveolar lavage fluid, etc. After the antibody appears, the culture can still be positive, meningoencephalitis, pericardium Inflammatory and bullous tympanitis can be taken from cerebrospinal fluid, pericardial effusion or middle ear secretions, and can also be isolated from mycoplasma. The pathogen examination is reliable and the specificity is high, but it is time-consuming, laborious, difficult to promote and apply, and does not help. Early diagnosis of the disease.

2. Serological examination is the most common method for the diagnosis of mycoplasma infection. After 2 weeks of onset, about 2/3 of the patients have a positive condensation test, and the titer titer is greater than 1:32, especially when the titer is gradually increased. Diagnostic value, this method has been used for many years in the clinic, because the condensation of antibodies (anti-erythrocyte I antigen IgM antibody) appeared earlier (first weekend of onset), the positive rate is higher (50% to 75%), and the decline is also fast ( It drops rapidly after 4 weeks, so it is still a simple, rapid and practical early diagnosis method, but it must be combined with clinical and other serological tests, such as complement fixation test, indirect hemagglutination test, indirect fluorescence. Antibody assay, enzyme-linked immunosorbent assay and growth inhibition assay, etc., since all antigens are prepared from Mycoplasma pneumoniae lipid extracts, they have specific diagnostic value, and the enzyme-linked immunosorbent assay is the most sensitive, which is helpful for judging recent infection. Indirect fluorescent antibody assay for IgG antibody appears late and long-lasting, suitable for epidemiological investigation; indirect hemagglutination IgM antibody appears early, disappears quickly, is more practical; growth inhibition test Strong heterogeneity, but long test period, the application of erythromycin, azithromycin and other effective drugs after the treatment of the impact of the judgment, about half of the patients were positive for streptococcal MG agglutination test, agglutination test for the diagnosis of Mycoplasma pneumoniae infection, but its sensitivity Both the specificity and the specificity are not ideal; the complement fixation test is not as sensitive and specific as other serological tests, but it is widely used because of its simple method.

3. Antigen detection for early diagnosis, commonly used methods are: solid phase enzyme immunoassay technology Elisa method, polyclonal antibody intermittent immunofluorescence assay, monoclonal antibody immunoblotting, nucleic acid hybridization technology and polymerase chain reaction technology, etc. The diagnosis is established by detecting the Mycoplasma pneumoniae antigen from the patient's nasopharyngeal secretions or sputum specimens. This method is quick and simple, and meets the clinical requirements, but its sensitivity, specificity and stability need to be further improved. The nucleic acid hybridization technology has been made into a kit. It is efficient, specific and sensitive, and easy to promote.

At present, the application of immunofluorescence method for sputum, pharyngeal secretion smear can be directly observed under the microscope to check mycoplasma, the method is simple and rapid, 1 ~ 2h can make a diagnosis, has been widely due to clinical.

4. Chest X-ray findings: The basic pathological manifestations of mycoplasmal pneumonia are bronchial and bronchiolitis and interstitial pneumonia. The chest radiographs are diversified, non-characteristic, and may have enhanced lung texture and multiple irregularities along the texture. The density is low, uniform patchy shadow, more than half of the multi-leaf distribution; nearly half of the two sides are violated, most cases have lower lobe involvement, lesions can be isolated in the surrounding area, but mostly stretch from the hilar to the lung field And gradually shallower fan-shaped shadows; one or more spots in the lungs are often spotted, the lesions are absorbed slowly, the elderly can reach more than 4 weeks, and about one-third of patients may have unilateral short-term pleural effusion.

Diagnosis and diagnosis of mycoplasmal pneumonia in the elderly

diagnosis

The clinical manifestations of mycoplasma pneumoniae pneumonia, chest X-ray signs and laboratory tests have no obvious characteristics, but its clinical symptoms are mild, and the physical signs are less than the relatively heavy chest X-ray performance is one of its characteristics, such as patients home school Similar to the occurrence or prevalence of similar diseases, patients with symptoms similar to upper respiratory tract infections, paroxysmal cough is prominent, lungs have various infiltration shadows and fewer signs, white blood cell count is not high, systemic toxic blood is mild , penicillin and cephalosporin treatment ineffective, there is a history of contact with this patient, low fever, wilting, weakness, loss of appetite should consider this disease.

Differential diagnosis

The disease should be differentiated from viral pneumonia, Legionella pneumonia, etc. The peripheral blood eosinophils are slightly normal and can be differentiated from eosinophilia.

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