Anaerobic pneumonia

Introduction to anaerobic pneumonia Anaerobic bacteria are the most common pathogens in lower respiratory tract infections. The main pulmonary infections are mainly aspiration pneumonia, followed by purulent passage, forming lung abscess or empyema, clinically 62% to 100% of aspiration pneumonia. It is caused by anaerobic bacteria. The anaerobic bacteria in the empyema account for 25% to 40%, and the individual is as high as 76%. Due to the collection of specimens, the exact proportion of anaerobic bacteria in bacterial pneumonia is not very clear. Some studies have shown that anaerobic bacteria in community pneumonia account for 21% to 33%, second only to S. pneumoniae, ranking second; There are reports of up to 35% in hospital pneumonia, but some believe that this data may be significantly overestimated. The disease is more common in the elderly and men over the age of 50. Clinical manifestations vary widely, and can be manifested as general acute bacterial pneumonia. Patients usually have fever, occasional chills, cough, cough, sputum, hemoptysis, often accompanied by chest pain. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: empyema

Anaerobic pneumonia

(1) Causes of the disease

Anaerobic bacteria usually have 4 categories:

1. Anaerobic cocci include Gram-positive pectostreptococcus, peptococcus, anaerobic streptococcus and Gram-negative veillonella, and Peptostase in pulmonary pleural infection This is especially common.

2. Gram-negative anaerobic gram-negative anaerobic bacilli are common in lung anaerobic infections, and Bacteroides is the first, followed by Clostridium, occasional genus, and bacteroides. The most common ones are B. fragilis, B. melaninogenicus, B. oralis, Fusobacterium, and F. nucleatum. , F. necrophrus, F. varium and F. mortifemm.

3. Gram-positive Bacillus-free Bacillus includes propionibacterium, eubacterium, lactobacillus, actinomyces and bifidobacterium in the lungs. Common bacteria in anaerobic infections are Mycobacterium, Propionibacterium, and Lactobacillus.

4. Clostridium cloacae, including Clostridium botulinum, Clostridium perfringens, tetanus, etc., rarely cause lung infection.

(two) pathogenesis

Under normal circumstances, normal anaerobic bacteria living in the human body are beneficial to the human body. When the body's defense function is weakened, the normal flora of the colonies changes, and the anaerobic bacteria leave the original place and transfer to the tissues and organs that are usually non-residential. Lead to endogenous infection, redox potential in human tissues can prevent anaerobic bacteria from propagating, host anemia in low immunoglobulinemia, complement deficiency, neutrophil deficiency, cell-mediated immune deficiency and other immune damage The chance of oxygen-bacteria infection increases, so it is speculated that the defense barrier damage of skin mucosa is the key to anaerobic infection and pathogenesis.

The main pathogenesis of anaerobic pneumonia includes: changes in upper respiratory flora, abnormal colonization, and various causes of inhalation. The latter is the most important. Periodontal disease (gingivitis and periodontitis) is the common source of anaerobic colonization. When the gingival cavity potential is -300mV, the amount of anaerobic bacteria can reach 1012CFU/g tartar, periodontal disease changes endogenous flora, increase anaerobic colonization, disturbance of consciousness, alcohol abuse, cerebrovascular accident, craniocerebral trauma, drug abuse General anesthesia, seizures, dysphagia, esophageal diseases, mental disorders, etc. are common causes of inhalation, bronchoconstriction, bronchial obstruction of bronchonews or other causes, bronchiectasis, pulmonary embolism and other lung diseases are also prone to anaerobic Infection with bacteria, infectious thrombophlebitis caused by blood-borne embolism caused by anaerobic infection of the lungs, abscesses, and caused by ipsilateral empyema.

Some studies have shown that the capsular polysaccharide of Bacteroides fragilis plays an important role in the formation of lung abscess. The melanin-producing bacillus also has certain characteristics similar to Bacteroides fragilis. Animal experiments have found that immunoregulatory T-cell lymphokines can be associated with anaerobic The bacterial antigens specifically act to regulate the formation of abscesses. The volatile short-chain fatty acids produced by anaerobic bacteria may be associated with the formation of odorous sputum in lung anaerobic bacteria. In acidic environments, short-chain fatty acids also inhibit alveolar macrophages and The phagocytic bactericidal action of neutrophils is not selective, and other bacteria are also protected. Therefore, anaerobic bacteria often form mixed infections with aerobic Gram-negative bacilli and staphylococcus.

Inhaled anaerobic pneumonia is mostly segmental distribution, initial alveolar wall edema and inflammatory cell infiltration of neutrophils, accompanied by pulmonary interstitial inflammation and mild to moderate mononuclear cell response, which can also be distributed along the bronchiole wall. And its surrounding tissue, similar to the pathological changes of bronchial pneumonia, generally after 7 to 16 days of inflammation can develop into necrotizing pneumonia or lung abscess, showing multiple small cavities, size 1 ~ 1.5m, necrotic area with a large number of pus or multinucleate Infiltration of granulocytes and necrotic lung tissue, chronic lung abscess is generally thicker, multiple or single, larger, mostly located in the subpleural pleura, ruptured to form empyema, pulmonary anaerobic infection with suppurative necrosis, abscess formation, The tendency of concurrent empyema (or bronchopleural fistula).

Anaerobic pneumonia prevention

Lung anaerobic infections, especially aspiration pneumonia, are mostly caused by aspiration, so try to minimize the risk of aspiration. When feeding patients with weakness, disturbance of consciousness and difficulty swallowing, special care should be taken to raise the bedside properly. If you notice the aspiration of the naked eye, you should immediately drain the body or attract the contents of the airway. If necessary, use fiberoptic bronchoscope to remove the food residue from the airway to avoid obstructing the bronchi. In addition, maintain oral hygiene and active treatment. Abdominal, pelvic septic infection can also reduce the incidence of anaerobic infection in the lungs.

The prognosis of pulmonary anaerobic infection depends on the patient's general condition, the type of infection and treatment is timely, old age, systemic failure, necrotizing pneumonia and bronchial obstruction are the determinants of poor prognosis.

Patients who start treatment at the stage of aspiration pneumonia can show the effect within 3 to 4 days, 7 to 10 days of fever, and continue to have high fever after 7 to 10 days of treatment. Fiberoptic bronchoscopy should be performed to determine the cause and drainage. Invalid, it is necessary to consider other diagnoses and other antibiotics, such as the occurrence of cavitary damage, it usually takes several months to absorb and close. If the diameter of the cavity is larger than 6cm, the cavity is difficult to close, and the symptoms often disappear after 8 weeks of treatment, such as pus The chest, even under effective drainage, takes an average of 29 days to get rid of heat.

The society has aspiration pneumonia, and the prognosis is good. A group of people reported that anaerobic pneumonia was the main cause of death, accounting for 4%, and the cause was 7%. On the contrary, the hospital received aspiration pneumonia, the mortality rate was as high as 20%, which may be serious. The underlying disease is related to the pathogenicity of Gram-negative anaerobic bacteria.

The mortality rate of lung abscess is as high as 34% before antibiotic application, and only 50% of patients survive, and have now dropped to 5% to 12%.

Anaerobic pneumonia complications Complications

Empyema, bronchopleural fistula. Ambition, irritability, lethargy, coma, etc. There were no obvious abnormalities in the early lung signs. Severe cases may have an increased respiratory rate, agitation of the nose, and cyanosis. Pulmonary consolidation has typical signs, such as percussion dullness, increased vocal fibrillation, and bronchial breath sounds, as well as wet rales. Complicated with pleural effusion, the affected side of the lungs percussion dullness, reduced vocal fibrillation, decreased breath sounds.

Symptoms of anaerobic pneumonia Common symptoms Bronchial purulent secretion increased fever with cough, slightly... Cold war purulent sputum thin sticky or purulent sputum... finger (toe) empyema hemoptysis pleural effusion

The disease is more common in the elderly and men over 50 years old. The incubation period of simple anaerobic pneumonia is 3 to 4.5 days. The lung abscess or empyema latency usually takes 2 weeks. The clinical manifestations are very different and can be expressed as general acute bacterial pneumonia. Patients usually have fever, occasional chills, cough, cough and sputum, hemoptysis, often accompanied by chest pain; can also be a subacute, chronic or similar TB occult infection, 40% to 60% of the lungs Abscess or empyema patients may have weight loss or anemia, of which chronic lung abscess or empyema almost have weight loss, anemia, and rarely occur in simple anaerobic pneumonia (5%), as a characteristic of anaerobic infection Odorous pus or pleural fluid is found in 50% to 70% of lung abscesses or empyema, but only 4% of anaerobic pneumonia is cough and sputum.

Pulmonary signs are manifested as consolidation or pleural effusion, and chronic lung abscess often has clubbing (toe).

Anaerobic pneumonia examination

Peripheral blood cells and neutrophils increased, especially in lung abscess and empyema, with an average of 1.5×10 ¹⁰ /L, 2.2×10 ¹⁰ /L, and the average number of white blood cells in pneumonia was 1.3×10 ¹⁰ / L, rarely more than 1.5 × 10 ¹⁰ /L.

Chest X-ray film showed a uniform, dense solid shadow distribution along the lung segment, more common in the posterior segment of the upper lobe, the dorsal segment of the lower lobe, the lung abscess was mostly round when formed, the inner wall was smooth, the wall of chronic lung abscess Thickening, the size of the abscess is different, the small one is only 1 ~ 1.5cm in diameter, the larger one can reach 13 ~ 15cm, the shape of the abscess is irregular, most of them are accompanied by liquid level, the blood infection is often bilateral, flaky, Patches appear to change, the lower leaves are more common, may be accompanied by empyema or pus.

Diagnosis and identification of anaerobic pneumonia

There are factors that induce inhalation and/or a clear history of inhalation of oral contents, fever, cough and sputum, chest X-rays showing pneumonia, lung abscess changes, clinical diagnosis can be established, but lung anaerobic infection There is no obvious cause of inhalation or inhalation; there are still 30% to 40% of patients without cough and sputum; the chest X-ray film lacks specificity; the diagnosis needs to collect non-polluting specimens for anaerobic culture under the condition of avoiding exposure to air. , pleural fluid, blood and application of anti-pollution techniques. Collection of secretions from the lower respiratory tract is a commonly recommended useful specimen. If necessary, the positive rate of anaerobic culture of puncture suction through the chest wall lung abscess can reach 84.5%, while blood culture The positive rate is only 5%.

The clinical manifestations of anaerobic pulmonary infections do not have the distinguishing characteristics, so the pneumonia caused by anaerobic bacteria, lung abscess and empyema should be differentiated from those caused by other bacteria.

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