Elderly pulmonary abscess

　　1. Etiology

　　The causes of lung abscess include various pyogenic bacteria, mycobacteria, fungi, or parasitic infections, with anaerobic bacteria (anaerobe) being the most common pathogens, such as Peptostreptococcus, Bacteroides, Melaninogenes, Bacteroides fragilis, Purple球菌, etc.; followed by various Gram-negative and Gram-positive bacteria, such as Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter freundii, Acinetobacter lophotrichus, Haemophilus influenzae, Haemophilus parainfluenzae, Legionella, Staphylococcus aureus, Streptococcus, Enterococcus faecalis, etc., less common bacteria include Pseudomonas aeruginosa, Streptococcus pneumoniae, etc.; in addition, certain fungal infections in diabetic patients and immunocompromised individuals can cause cavities, such as Nocardia, Actinomyces; parasites such as Entamoeba histolytica, an important but not common pathogen of lung abscess, mainly causing abscesses in the basal part of the lower lobe; mycobacteria such as Mycobacterium tuberculosis, Mycobacterium avium, and intracellular mycobacteria can also cause lung abscess. In lung abscesses acquired outside the hospital, anaerobic infections account for 60% to 85%, and most are mixed infections of several anaerobic bacteria. Recent research shows that 10% to 15% of Bacteroides fragilis, 60% of non-fragile Bacteroides, and 40% of Bifidobacteria can produce beta-lactamase, so the infection of penicillin-resistant anaerobes has become an issue that cannot be ignored. In hospital-acquired lung abscesses, mixed infections of Gram-negative bacilli and positive球菌 are common.

　　2. Pathogenesis

　　Clinically, it is divided into 3 types.

　　1. Aspiration lung abscess

　　Formed by the aspiration of contents from the oropharynx and nose. In lung abscesses caused by anaerobic bacterial infections, 85% to 90% of cases have a history of aspiration of oral contents or have risk factors such as periodontal disease. Conditions such as altered consciousness (anesthesia, alcohol intoxication, use of sedatives, head injury, cerebrovascular accidents, and grand mal seizures), swallowing disorders caused by various reasons, gastroesophageal reflux, degenerative or acute neurological diseases, the destruction of the normal defense system of the airway, suppression of the cough reflex, and changes in the quality of oral contents due to periodontal disease can all become causes of aspiration of pathogens. However, 10% to 15% of patients have no obvious periodontal disease or aspiration risk factors.

　　The occurrence of aspiration lung abscess is related to the anatomical characteristics of the bronchi, as the inhaled material moves with gravity and blocks the bronchi in a certain lobe of the lung. Due to the greater angle of the left main bronchus compared to the right, and the wider diameter of the bronchus, the chance of lung abscess occurring in the right lung is twice that of the left lung. In the supine position, lung abscesses tend to occur in the dorsal segment of the lower lobe or the posterior segment of the upper lobe, accounting for 75% of all lung abscess cases. In critically ill patients in the intensive care unit, due to the use of histamine H2-receptor antagonists to prevent stress ulcers, there is an increase in the colonization of Gram-negative bacilli in the oral cavity, thus, such patients are prone to lung abscesses caused by Gram-negative bacilli infections.

　　2, Bacteremia of hemogenous lung abscess

　　Occasionally, bacteria or emboli in the pus or abscess lesions can reach the lungs through the blood circulation, causing pulmonary arteriole embolism and forming hemogenous lung abscess. It is common in staphylococcal sepsis, acute suppurative osteomyelitis, suppurative appendicitis, otitis media, postpartum endometritis, and subacute bacterial endocarditis, and can also be seen in suppurative infections of the face and skin.

　　3, Secondary lung abscess

　　Certain bacterial pneumonias such as staphylococcal pneumonia, pneumococcal pneumonia, Haemophilus influenzae pneumonia, and legionella pneumonia can develop into cavity lesions and secondary lung abscesses. When tumors or foreign bodies block the bronchus, it can cause retention of secretions in the distal part, secondary bacterial infection leading to lung abscess.

　　1, Pyopneumothorax:Mostly secondary to pulmonary infections such as pneumonia, lung abscess, and empyema. Pneumonia or empyema can cause rupture of alveoli or small bronchi at the edge of the lung, forming bronchial fistulae, leading to communication between the pleural cavity and the bronchial system, becoming pneumothorax. If there is pus in the pleural cavity, it becomes pyopneumothorax. Staphylococcal pneumonia can easily cause small lung abscesses to rupture into the pleural cavity and form pyopneumothorax.

　　2, Metastatic abscess:It is a localized collection of pus in tissues, organs, or body cavities caused by pathogenic bacteria from distant primary infection sources, which come through blood flow, lymphatic vessels, and cause tissue necrosis and liquefaction during the infection process.

　　One, Symptoms

　　1, Onset: Acute lung abscess patients may have an infection focus in the oropharynx and risk factors for aspiration, or a history of catching a cold and overexertion, the onset can be abrupt, patients may feel cold, high fever, after 8-14 days of lung cavity formation, patients cough out a large amount of foul-smelling purulent sputum, body temperature drops significantly. In a few patients, the onset may be concealed, weakness, cough, and low fever may last for several weeks or even longer, secondary lung abscesses following pneumonia may appear 2-3 weeks after the disease, at this time, pneumonia should have been cured, but recurrent high fever, increased amount of sputum, and often symptoms of weakness.

　　2, Cough, large amounts of purulent sputum: Initially, coughs mucous or mucopurulent sputum, after 8-14 days of lung cavity formation, 40%-70% of cases cough out large amounts of foul-smelling sputum, the smell of sputum suggesting anaerobic bacterial infection.

　　3, Hemoptysis: Not uncommon, it can occasionally cause fatal massive hemoptysis.

　　4, Chest pain: Caused by inflammatory lesions involving the pleura, pain worsens during breathing. If the abscess breaks into the pleural cavity, it can form empyema, pyopneumothorax, or encapsulated empyema due to fibrin wrapping, which limits the patient's respiratory movement and exacerbates dyspnea.

　　5, Other: Weakness, emaciation, anorexia, etc., anemia and consumption symptoms are common in chronic lung abscess (chronic lung abscess) and empyema patients. The blood源性 lung abscess often has symptoms caused by the primary disease, and symptoms such as anemia are common in chronic lung abscess and empyema patients.

　　Second, signs

　　When the abscess is small and located deep, there may be no positive signs; if the abscess is large, there may be signs of lung consolidation locally, such as a hollow sound if the abscess is close to the chest wall; signs of pleural effusion appear on the affected side in patients with empyema; clubbing can appear within a few weeks of onset, and is often seen in chronic lung abscess patients, and sometimes also suggests the possibility of bronchogenic lung cancer. Hemogenic lung abscess often has no positive signs in the lungs due to small, scattered lesions.

　　1, Avoid using long-acting anesthetics, and use less painkillers after surgery as well, because such drugs suppress the cough reflex. It is advisable to fill the lungs with a mixture of air and oxygen at the end of anesthesia because the slow absorption of nitrogen can increase the stability of alveoli.

　　2, Encourage coughing and deep breathing, inhale aerosol bronchodilators, and nebulize water or saline to liquefy secretions and facilitate their expulsion. Bronchial aspiration should be performed if necessary.

　　3, Use intermittent positive pressure breathing and lung volume meter, and use a simple device that can maintain maximum expiration for 3 to 5 seconds. Various physical therapy measures such as tapping, vibration, position drainage, and deep breathing can also be used. Various physical therapy methods must be used properly, accompanied by routine measures to achieve the desired effect.

　　First, blood picture

　　Total white blood cell count increased, neutrophil nuclear left shift, toxic granules may be present, and hemoglobin decreased are more common in chronic lung abscess patients.

　　Second, bacteriological examination

　　1, Smear:Gram staining of sputum smear, if a large number of neutrophils are seen, and a large number of bacteria inside and outside the cells, and sputum culture is negative, it suggests anaerobic bacterial infection.

　　2, Culture:Sputum culture is the most widely used, a non-invasive method to understand the pathogenic bacteria, but it is easily contaminated by upper respiratory tract bacteria. For anaerobic bacteria, due to frequent contact with air, it often affects the positive rate of culture. It is more meaningful to collect specimens by tracheal aspiration and protective brush collection through fiberoptic bronchoscope or by pleural fluid puncture to collect pleural pus and immediately perform anaerobic and aerobic culture. Since the positive rate of pathogenic bacteria culture is not very high, some new technologies such as gas chromatography to detect bacterial metabolic products for bacterial identification, DNA probe hybridization technology, etc., are being studied for rapid bacterial identification. Blood culture can be used for the diagnosis of hemogenic lung abscess.

　　Three, X-ray examination

　　Generally, chest X-ray can obtain clear lung abscess images, and the X-ray imaging characteristics of lung abscess.

　　Four, CT examination

　　Further examination can reveal multiple small abscess cavities that appear when necrotic pneumonia occurs.

　　Old-age lung abscess should have a light diet, eat more fresh vegetables, beans, and fruits such as spinach, green vegetables, chive, radish, soybeans, tofu, oranges, loquat, pear, walnut, etc. Avoid foods: Avoid all spicy and刺激性 foods such as scallions, garlic, chives, peppers, ginger; Avoid smoking and drinking; Avoid greasy and hot foods to prevent phlegm and fire; Avoid seafood and other irritants such as sea fish, shrimps, crabs, etc.; Avoid overly salty foods.

　　I. Treatment

　　1. Antibiotic Treatment

　　(1) Drug selection: For aspiration lung abscess, it is mainly caused by anaerobic bacteria.

　　For the treatment of lung abscess caused by anaerobic bacterial infection, the choice of medication should be based on the pathogen of infection, such as second-generation cephalosporins (cefuroxime, cefaclor) or third-generation cephalosporins (ceftriaxone, cefotaxime, cefoperazone), fluoroquinolones (ofloxacin, levofloxacin), and in necessary cases, aminoglycoside antibiotics (such as amikacin) can be used in combination; if methicillin-resistant Staphylococcus aureus is involved, vancomycin can be selected; if the lung abscess is caused by amoebae, metronidazole should be used for treatment.

　　(2) Duration of drug treatment: 4 to 8 weeks, or longer, until the abscess is healed as shown on the chest X-ray.

　　2. Sputum Drainage

　　For patients with good general condition, appropriate postural drainage can be adopted, supplemented with nebulized inhalation. Fiberoptic bronchoscopy aspiration can help drainage, but should not be used repeatedly.

　　3. Other Treatments

　　Supportive therapy, strengthening nutrition, correcting anemia, and using bronchodilators, expectorants, and antispasmodics to relieve spasm and expectoration.

　　4. Surgical Treatment

　　Most patients can be cured with effective antibiotic treatment, and a few patients with poor treatment effects may consider surgical treatment. The main indications for surgery are: disease duration over 3 months, no improvement after medical treatment; sudden massive hemoptysis in chronic lung abscess, ineffective after drug treatment; with bronchial obstruction, difficult to control infection, and those who cannot be ruled out as lung tumor. Those with bronchopleural fistula or empyema, with poor efficacy after repeated fluid aspiration and lavage, should also undergo surgical treatment.

　　II. Prognosis

　　The previous mortality rate of acute lung abscess was 34%, and the mortality rate has been below 5% after the use of antibiotics. For aspiration lung abscess or lung abscess secondary to pneumonia, with timely and reasonable treatment, the body temperature can return to normal within 7 to 21 days, but the abscess cavity closure requires several months. Chronic lung abscess can be complicated with brain abscess, other metastatic abscesses, amyloidosis, fatal massive hemoptysis, and bronchopleural fistula, etc., which are not common now.