Streptococcus pneumoniae pneumonia

Introduction to pneumococcal pneumonia According to some investigations, the pathogens are most common with Streptococcus pneumoniae types 1, 2, 3, 4, 6, 7, 8, 12, 14, 18 and 19, while children are 1, 6, 14, 18, 19 and 23 More. Carriers are the main source of infection, and the source of infection of patients is very small. The pathogens are discharged through the nasopharyngeal secretions and spread by droplets. The dense population occasionally erupts and pops, and generally spreads. There are many cases in the four seasons, and there are more winter and spring. The incidence of men is more than that of women. Secondary pneumonia is more common in children, elderly and chronic patients. The normal upper respiratory tract has a protective barrier and is therefore less susceptible to infection. Once the barrier is compromised, the defense function is reduced and can occur. The above respiratory virus infection can increase mucus secretion, inhibit the function of ciliated epithelium and the role of phagocytic cells. Anesthesia can attenuate epiglottic reflexes and cause aspiration of gastric contents and nasopharyngeal bacterial secretions, heart failure, septic shock, and chest trauma. Water accumulation in the alveoli, bronchial cancer, bronchiectasis and lung abscess can cause bronchial obstruction, poor drainage, can induce the disease. basic knowledge The proportion of illness: 0.0580% Susceptible people: more common in children, the elderly Mode of infection: respiratory transmission Complications: congestive heart failure, jaundice, sepsis

The cause of pneumococcal pneumonia

(1) Causes of the disease

The bacteria are spear-headed and often arranged in pairs, so they can also be called pneumococci. They can be short-chain in liquid culture. On the solid medium, grass green rings can appear around the colonies, and the central part of the colonies can be autolyzed. The role of the umbilical or volcanic mouth, using the gene classification method belongs to the third group, namely the light streptococcus group, the bacteria have three antigens, the cell membrane composed of lipids and teichoic acid is F The cell wall composed of antigen, non-specific, peptidoglycan, teichoic acid and choline phosphate is a C polysaccharide antigen, which is species-specific and shared by various types of Streptococcus pneumoniae. The capsular polysaccharide antigen is type-specific. Sex, there are currently 90 serotypes, the United States called 1,2,3...90, while Danish is named according to the similarity of antigens, the first discoverer is called F(first), and then the discoverer is A. , B, C, etc., for example, 19A, 19B and 19C, which are corresponding to 19, 57, 58 and 59 in the American nomenclature, and the capsule resists the phagocytosis of the host, which is an important virulence factor of the bacteria. This bacterium can produce autolysin, pneumolysin, Neuramindase, as well as cell surface protein A, surface adhesion protein A, choline-binding protein, etc., have certain pathogenic effects in the process of infection.

The bacteria are not resistant to physical and chemical factors in the external environment, and can be killed by direct sunlight for 1 hour. Currently, commonly used disinfectants such as 0.2% povidone iodine (iodine) solution, chlorine disinfectant (containing effective chlorine) It can be killed in 10mg in 500mg/L, but it can survive for more than 1 month in dry sputum without sunlight.

(two) pathogenesis

In normal people, although there are bacteria in the nasopharynx, but not in the disease, the cilia of the tracheal mucosa, the macrophages in the alveoli can remove the invading bacteria, but when the body's defense function is reduced, the bacteria can be colonized, multiplied, causing local tissue. Inflammatory reaction, leading to solid degenerative lesions in the lungs; such as bacteria entering the bloodstream, causing sepsis, causing purulent meningitis through the blood-brain barrier; occasionally endocarditis, osteoarthritis and other suppurative reactions, in The most important mechanism in the process of onset is that the bacteria can multiply in the host tissue and cause a strong suppurative inflammatory response. The surface protein A of Streptococcus pneumoniae, adhesion protein A and choline-binding protein can make the bacteria adhere to On the host, neuraminidase can lyse the sialic acid of the mucosal cells, allowing the bacteria to colonize. The capsular polysaccharide can resist the phagocytosis of the host, and the bacteria can multiply. The autolysin can bind the cell wall of teichoic acid and peptidoglycan. Released to activate complement (classical and bypass pathways), pneumolysin also activates the alternative pathway of complement, causing a strong inflammatory response, not only It is now organized with congestion, edema, inflammatory cell and fibrin exudation, and accompanied by a large number of interleukin-1, tumor necrosis factor alpha, etc., aggravating the inflammatory response, the severity of the disease and the degree of inflammatory response are closely related.

Streptococcus pneumonia prevention

Patients are not contagious and usually do not quarantine. Contactors generally do not need special treatment. For children under 4 years of age, patients with low cellular immunity such as sickle cell anemia can be treated with penicillin for a short period of time. In some areas since 1978 Since the beginning of the year, it has begun to supply multivalent S. pneumonia capsular polysaccharide vaccine, suitable for children with frail diseases over 2 years old, especially those without spleen, sickle cell anemia, nephrotic syndrome, chronic cardiopulmonary disease and immune function. Inferior, can produce type-specific protective immunity after injection for several years.

Complications of pneumococcal pneumonia Complications, congestive heart failure, jaundice sepsis

It should be noted that a small number of patients may have acute gastric dilatation, ileal toxic paralysis, shock, congestive heart failure, hemolytic jaundice, venous thrombosis, and some cases may include herpes simplex, sepsis, empyema, pericarditis, pleurisy, arthritis, etc. .

Symptoms of pneumococcal pneumonia Common symptoms Chest pain, cold war, lung insufficiency, snoring, jugular vein anger, decreased blood pressure, increased lung texture

symptom

The incubation period is 1 to 2 days. Most of the patients have a history of upper respiratory tract infection before the onset of illness. It can also occur in healthy young adults, but often suffer from cold, rainy history, sudden chills, fever, severe chest tingling or knife cutting. Pain, often accompanied by coughing and breathing, so that the patient is well lie to the affected side, restricting the thoracic movement of the side to relieve chest pain, severe cases extend to the pleural pleura, chest pain involves the lower chest, upper abdomen or shoulder, irritating Dry cough, may have a small amount of sticky, with blood or rust color, a wide range of lesions have anxious and cyanosis, severe cases often accompanied by vomiting, abdominal distension, jaundice, myalgia, weakness, a small number of visible blood pressure drop and shock.

Sign

Chest signs can not be obvious at the beginning, the consolidation period can have percussion dullness, auscultation of bronchial breath sounds, increased vocal fibrillation, wet voice; pleural inflammation, there are pleural friction sounds and local chest wall tenderness, such as organ displacement, suggesting atelectasis (moving to the affected side) or pleural effusion (moving to the healthy side), such as jugular vein engorgement, liver enlargement, suggesting that combined with heart failure, peripheral blood: white blood cell count often increased to (20 ~ 30) × 109 / L The neutrophils reach 80%, with the left nucleus and poisoning particles, and the white blood cell count of the old and weak patients may not increase.

Examination of pneumococcal pneumonia

1. When the blood is infected with the whole body, the white blood cells can be significantly increased (20~30)×109/L, and the neutrophils account for about 90%. The elderly and immunocompromised people have no obvious increase in white blood cells, but the classification is still neutral. More than 80%.

2. Bacterological examination The secretions of the suppurative lesions (such as sputum, pus, cerebrospinal fluid) smear Gram staining to find bacteria, and bacterial culture, fever patients should still do blood culture, get S. pneumoniae as the basis for diagnosis.

3. Cerebrospinal fluid examination CSF patients with CSF showed a purulent-like change, the appearance of rice soup, protein is often above 1g / L, white blood cells more than 500 × 106 / L, multinuclear majority, sugar and chloride reduction.

4. Immunological examination The detection of capsular polysaccharide antigen in serum neutralizing CSF by latex agglutination test or convection electrophoresis is helpful for the diagnosis of negative bacteria culture.

5. X-ray examination for chest infection should be chest X-ray examination, beginning only the lung texture thickening and local light infiltration image, the perspective is easy to be ignored, should be filmed, the lobe can be seen after the large leaf or segment Slightly dense shadows, increased brightness during the dissipation period, and 2 to 3 weeks for the shadow to completely dissipate.

Diagnosis and identification of pneumococcal pneumonia

Diagnostic criteria

1. X-ray chest examination showed only increased lung texture at the beginning of the disease, and the solid deformation period showed a typical large thick shadow. Most of them started from the right middle lobe or one side of the lower lobe, mostly limited to one leaf, and a few were limited to single-lung segment, occasionally The gap bulges.

2. Pathogen examination

(1) bacteriological examination: sputum, throat swab smear and culture, see S. pneumoniae, can be passed through bile hemolysis test, serological reaction, glucose fermentation reaction, ethyl hydrogenated hydroxyquinine sensitivity test and alpha hemolytic streptococcus Identification, such as less sputum or mixed with bacteria and difficult to separate, can be injected into the abdominal cavity of mice, in the sudden death of blood and abdominal effusion for culture, can be obtained pure culture, if necessary, can do capsular swelling test, Precipitation, agglutination, etc. to identify the bacterial type.

(2) Serological diagnosis: taking sputum, blood and body fluid by convective immunoelectrophoresis detection of specific polysaccharide antigen, is helpful for diagnosis; even if it has received antibacterial treatment, it can be measured.

Differential diagnosis

1. Other bacterial pneumonia The clinical identification of pneumonia caused by Klebsiella pneumoniae, Staphylococcus aureus, Group A streptococci, etc. is not easy, and usually must be confirmed by the pathogen examination of sputum.

(1) Pneumococcal pneumonia: There are many sputum sputum, and the typical ones are brown-red jelly. The early X-rays are large flocculent, with different shades and shadows. Both sides are more common, and the changes are rapid. The lesions are honeycomb-shaped, with hollow or large lungs. Bubble formation, easy to have a pneumothorax or empyema is its characteristics.

(2) tuberculosis: slow onset, mild symptoms of poisoning, white sticky or a small amount of purulent, lung lesions above the lesion site, followed by the middle leaf, the lower leaves are rare.

(3) Bronchial pneumonia: such as parrot disease.

(4) Rickettsia pneumonia (such as Q fever): no chills, blood stasis, severe chest pain and significant leukocytosis, chest signs are not obvious.

(5) Tular pneumonia.

(6) Legionella pneumoniae pneumonia: relatively rare, should be identified in the epidemic area, so as not to misdiagnose.

2. Pulmonary infarction is often secondary to patients with valvular heart disease or venous thrombosis. The disease also has difficulty breathing, pleural pain, hemoptysis, fever or lung consolidation and X-ray findings, all similar to acute lung infection, but The initial symptoms of pulmonary infarction are sudden severe pain, rare chills, general no respiratory prodromal symptoms and cold sores; fever is not high, whole mouth hemoptysis is common, lung signs appear very early, white blood cell count up to 20 × 109 / L is rare , combined ventilation. Perfusion radionuclide scanning, pneumonia and pulmonary infarction showed similar defects, pulmonary infarction with perfusion defects without corresponding ventilation defects, blood DNA determination, seems to help diagnose pulmonary embolism, such as pulmonary infarction Infection, it is more difficult to distinguish from primary bacterial pneumonia. NBT test may help to identify, because pneumonia should be treated with antibacterial therapy and pulmonary infarction should be treated with anticoagulation, so it must be correctly distinguished.

3. Lung insufficiency is caused by bronchial obstruction. Not only many signs are similar to pneumonia, but persistent obstruction can also lead to serious infection. Inhalation of a large amount of mucus after surgical anesthesia is the main cause of atelectasis, which may have difficulty breathing, cough, chest pain, and one side. Decreased thoracic motion, voiced sounds, reduced breath sounds, are similar to primary pneumonia, and have fever and leukocytosis, also appear to have infection, because atelectasis may be eliminated by strong cough, body position drainage or bronchoscopy, etc. Should be distinguished from primary pneumonia, sometimes due to significant displacement of the mediastinum (to the side of the disease) is conducive to identification, tumor compression and aortic aneurysm can be long-term compression of the bronchus leading to chronic atelectasis, should also be carefully discerned.

4. Underarm infection is easily confused with pneumonia, underarm abscess, liver abscess and other infections in the upper abdomen may involve diaphragmatic sputum, causing local inflammation, small amount of fluid in the chest, chest pain and atelectasis; at the same time, pneumonia can sometimes Similar to intra-abdominal diseases, pleurisy can cause abdominal pain, suspected acute appendicitis or cholecystitis.

5. Other diseases Pneumococcal pneumonia has been identified, but the possibility of another potential disease in the lung should also be considered. Chronic obstructive pulmonary disease and lung abscess may cause recurrent bacterial pneumonia, and its own symptoms until Pneumonia dissipates only to show up, bronchial cancer or any other disease, partially blocking the bronchi, often leading to repeated episodes of pneumonia in the same lung segment.

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