Pneumococcal pneumonia

　　Pneumococcus, also known as diplococcus pneumoniae or pneumococcus, is a Gram-positive diplococcus belonging to the genus Streptococcus. Pneumococcus is typed according to its capsular specific polysaccharide antigen, with 84 types currently recognized in Denmark (the Danish Serum Institute is the only source of antiserum recognized by WHO), and 86 serotypes in the United States. China conducted a nationwide survey of pathogenic strains in the 1980s, and the most common strains isolated from blood, cerebrospinal fluid, and middle ear secretions were serotype 5, followed by 6, 1, 19, 23, 14, 2, 3, and others. The third type is the most virulent, and children are mostly serotypes 6, 14, 19, and 23. Pneumococcus can cause lobar pneumonia, which is all primary, most commonly seen in children over 3 years old, with older children more affected. Therefore, as the body's defense ability gradually matures, the lesions can be confined to a lobe or segment of the lung without spreading. It can occasionally occur in infancy and early childhood. When the climate changes abruptly, the body's resistance decreases, leading to more cases, which are more common in winter and spring and may be related to the prevalence of respiratory virus infections.

　　In addition to general symptoms, it can also cause other diseases. Patients with pneumococcal pneumonia who do not receive appropriate treatment may develop empyema, lung abscess, myocarditis, pericarditis, and other complications. Sepsis patients may develop septic shock. Complications after antibiotic treatment are rare.

　　1. Symptoms:A few patients may have prodromal symptoms, and the onset is often acute. Sudden high fever, chest pain, anorexia, fatigue, and restlessness. The body temperature may reach 40 to 41 degrees Celsius. Rapid breathing may reach 40 to 60 times per minute, with sighing on expiration, flaring of the nostrils, and flushed or cyanotic complexion. Chest pain may occur during breathing, so the child often lies on the affected side. Initially, coughing is usually not severe, without sputum, but later, sputum may become rust-colored. Early vomiting is common, and a few children may have abdominal pain, which is sometimes misdiagnosed as appendicitis. Young children may have diarrhea. Mild cases are usually alert, and a few children may have symptoms such as headache and neck stiffness, indicating meningeal irritation. In severe cases, there may be seizures, delirium, and coma, indicating toxic encephalopathy, which is often misdiagnosed as central nervous system diseases. Severe cases may be accompanied by septic shock, and in some cases, brain herniation may occur due to brain edema. Older children may have herpes on the lips.

　　2. Chest signs:Early in the disease, there may be mild dullness on percussion or decreased breath sounds. After 2 to 3 days of the course, there may be typical dullness on percussion, increased tactile fremitus, and tubular breath sounds. Wet rales may be heard during the resolution phase. In a few cases, no abnormal chest signs may be observed throughout the disease. X-ray examination is necessary for diagnosis.

　　3. X-ray examination:Early in the disease, lung markings may deepen or be limited to a segmental thin shadow. Later, there may be large areas of shadow that are uniform and dense, occupying a whole lobe or a segment (Figure 24-8), which gradually dissipate after treatment. Lung bullae may be visible. In a few cases, pleural effusion may occur. It is worth noting that consolidation may be detected by X-ray before pulmonary signs appear. Most children have X-ray shadows disappear 3 to 4 weeks after the onset of the disease.

　　4. Natural course:Most patients experience a sudden drop in body temperature between the 5th and 10th day of the illness, with a decrease of 4 to 5 degrees Celsius within 24 hours, and when the temperature drops to about 35 degrees Celsius, there may be profuse sweating and weakness, resembling a shock-like state. Patients treated with antibiotics early may have a fever subsided within 1 to 2 days, and pulmonary signs may disappear about a week later.

　　In some countries and regions, high-risk populations prone to pneumococcal infections (including children, especially those with sickle cell disease) have tried multivalent pneumococcal polysaccharide vaccines for prevention, and they are considered effective. Research on this is still ongoing.

　　The pneumococcal vaccine used in China is the 'multivalent pneumococcal vaccine' (Pneumovax 23), developed and produced by Merck & Co., Inc. in the United States, and approved by the Chinese Ministry of Health for nationwide implementation.

　　This vaccine is made by killing the pneumococci and extracting their capsule polysaccharides. After vaccination, it induces the production of antibodies, effectively preventing pneumococcal pneumonia and sepsis. This vaccine includes 23 species of pneumococci that mainly cause pneumonia and sepsis, providing immunity to 90% of pneumococci, hence the name 'multivalent'. After a single injection, protective antibodies are produced within 15 days, with a protection period of at least five years; if necessary, a second injection is administered in the sixth year after the first injection.

　　White blood cells and neutrophils are significantly elevated, with the total white blood cell count reaching above 20×10^9/L, occasionally reaching 50×10^9 to 70×10^9/L. However, the total white blood cell count of a few children may be low, often indicating severe illness. Culturing of airway secretions, blood, and pleural fluid can obtain Streptococcus pneumoniae. In addition, the capsular antigen of Streptococcus pneumoniae can be detected from blood and urine specimens using methods such as CIE and LA, and antibodies to Streptococcus pneumoniae can be measured as an auxiliary diagnosis using methods such as radioimmunoassay, killing power test, and ELISA. Urinalysis may show trace protein. C-reactive protein is often positive.

　　During the acute phase of Streptococcus pneumoniae pneumonia, attention should be paid to controlling the diet, with liquid food as the mainstay, and some high-quality protein foods and fruit and vegetable juices can be taken to help the recovery of the body.

　　After stable condition, it is necessary to pay attention to eating more foods rich in protein and carbohydrates appropriately, and it is advisable to avoid catching a cold and avoid eating cold, spicy, and irritating foods.

　　1. General therapy

　　Please refer to the section on bronchopneumonia treatment. As the majority of Streptococcus pneumoniae strains are still sensitive to penicillin, penicillin G is generally used for rapid cure. The common dose is 50,000 to 100,000 units per kilogram per day, or 6,000,000 to 10,000,000 units or more per day, administered intramuscularly or intravenously in four divided doses. Children with penicillin allergy can be given erythromycin intravenously at a dose of 100mg per kilogram per day, and can be switched to oral administration after improvement. Treatment should last for 1 to 2 weeks, or 3 to 5 days after complete resolution of fever. If there is no improvement in the condition after 2 to 3 days of penicillin administration, consider rare penicillin-resistant strains and switch to other antibacterial drugs. Other drugs can be changed according to the sensitivity test results of Streptococcus pneumoniae isolated from throat swabs. Since specific pathogen diagnosis of pediatric pneumonia often cannot be made within 24 hours, broad-spectrum antibiotics can be used to treat pneumonia caused by unknown pathogens. In recent years, first and second-generation cephalosporins such as cefazolin (Cefazo1in), cefalothin (Cefalot-hin), and cefaroxime (Cefaroxime) have been widely used. For cases with infectious shock or cerebral edema and cerebral hernia, rescue measures should be taken according to the specific chapters on infectious shock or intracranial hypertension. For late presenters, attention must be paid to common complications such as empyema, lung abscess, pericarditis, myocarditis, and toxic hepatitis, and appropriate treatment should be provided. Empyema requires aspiration of pus. Streptococcus pneumoniae does not produce true exotoxins, and the capsular polysaccharide antigen does not cause tissue necrosis. Therefore, lobar pneumonia usually does not leave lung damage. However, scars left in the lung from multi-lobe pneumonia can occasionally cause chronic restrictive lung disease.

　　Secondly, Western Medicine Treatment

　　1. Antibacterial Drug Treatment

　　Antibacterial drug treatment should be given as soon as the diagnosis is made, without waiting for the results of bacterial culture. The first choice is penicillin G, and the route of administration and dosage depend on the severity of the condition and the presence of complications: for young adult patients, 2.4 million U/d can be used, administered intramuscularly in three divided doses, or procaine penicillin can be injected intramuscularly at 600,000 U every 12 hours. For patients with slightly more severe conditions, penicillin G 2.4 million to 4.8 million U/d should be used, administered intravenously in divided doses, once every 6-8 hours; for severe patients and those with meningitis, the dose can be increased to 10 million to 30 million U/d, administered intravenously in four divided doses. For patients allergic to penicillin or those infected with penicillin-resistant or multidrug-resistant strains, respiratory fluoroquinolones, cefotaxime, or ceftriaxone, etc., can be used. For patients infected with multidrug-resistant strains, vancomycin or teicoplanin can be used.

　　2. Supportive Therapy

　　Patients should rest in bed, pay attention to supplementing sufficient protein, calories, and vitamins. Closely monitor the changes in the condition and prevent shock. For patients with severe chest pain, a small amount of analgesic can be used, such as codeine 15mg. Do not use aspirin or other antipyretics to avoid excessive sweating, dehydration, and interference with the true fever pattern, leading to incorrect clinical judgment. Encourage drinking 1-2L of water per day. Mild patients do not need routine intravenous fluid administration, and intravenous fluid can be administered if dehydration occurs, maintaining a urine specific gravity of 1.020. Below, serum sodium should be kept below 145mmol/L. For moderate or severe patients (PaO2

　　3. Management of Complications

　　After treatment with antibacterial drugs, high fever often subsides within 24 hours or gradually decreases within several days. If the body temperature drops and then rises again or does not decrease after 3 days, consider extrapulmonary infection caused by Streptococcus pneumoniae, such as empyema, pericarditis, or arthritis, etc. Other causes of persistent fever include penicillin-resistant Streptococcus pneumoniae (PRSP) or mixed bacterial infection, drug fever, or coexisting other diseases. When a tumor or foreign body blocks the bronchus, although the pneumonia can be resolved after treatment, the blocking factor is not removed, and pneumonia may appear again. About 10%-20% of Streptococcus pneumoniae pneumonia cases are accompanied by pleural effusion, and pleural fluid should be collected for examination and culture to determine its nature. If the treatment is not appropriate, about 5% of cases develop empyema, and active drainage should be performed.