Pneumocystis carinii pneumonia in children
Introduction
Introduction to Pneumocystis pneumonia in children Pneumocystis carinii (PC) is currently considered to be a type of protozoa. The life history of PC is not fully understood, but it is known to be a common infection of humans and animals. PC pneumonia is an opportunistic infectious disease that occurs on the basis of immunodeficiency in the host. basic knowledge The proportion of illness: 0.005% Susceptible people: children Mode of infection: respiratory transmission Complications: pediatric acute respiratory distress syndrome
Cause
Pediatric cardinal pneumonia pneumonia
(1) Causes of the disease
The pathogen is Pneumocystis carinii, which is divided into trophozoites and cysts, mainly in the lungs. It was thought to belong to the protozoa in the past. Recently, some scholars have found that the DNA of Pneumocystis carinii has homology with fungi, according to its ultrastructure. And the analysis of the development of ribosomal RNA germline of Pneumocystis is that Pneumocystis is a fungus, but its morphology and sensitivity to drugs are similar to those of protozoa. The disease is transmitted by air and droplets, although PC is widely infected. Humans and animals, but usually only a few insects are parasitic in the alveoli (hidden infection), such as when encountering weak infants, congenital immunodeficiency and sick children with immunosuppressive drugs, such as sick children with immune dysfunction, It begins to proliferate rapidly, causing pneumonia. If the air in the baby room is contaminated by PC, it can cause mutual infection between the newborns. Most of the elderly and adults are subject to a large number of long-term hormone therapy, malignant tumors (leukemia, lymphoma). Chemotherapy, patients receiving immunosuppressive therapy after organ transplantation.
(two) pathogenesis
Two forms of Pneumocystis carinii can be seen in the alveolar cavity: one is a capsule of 5-8 nm in diameter, containing 8 polymorphic intracapsular sporozoites; the other form is an extracapsular trophozoite, which is a sac After the sporozoites, Pneumocystis carinii is attached to type I alveolar cells via fibronectin, and alveolar macrophages phagocytose and kill Pneumocystis carinii, releasing tumor necrosis factor, Pneumocystis carinii pneumonia 2 Histopathological type: a kind of interstitial plasma cell pneumonia in infants, which can be seen in 3 to 6 months of frail infants, sometimes with outbreaks, showing extensive thickening of alveolar septa, mainly by plasma cell infiltration, another The type is more common in children with immune injury. It is diffuse desquamative alveolitis. The alveoli contain a large number of Pneumocystis carinii. The alveolar macrophages have foam-like changes. The alveolar septal infiltration is different from the infant type, usually without plasma cells. infiltration.
Prevention
Pneumocystis pneumonia prevention in children
The prevention of PCP clinically with SMZ-TMP has been successful. Harris et al. 229 patients with high-risk pediatric tumors of PCP were treated with SMZ-TMP 204 mg/(kg·d), of which ALL started at prevent CNST (Day 28). Dosing for at least 1 year; patients with ANLL or solid tumors were given chemotherapy at the same time as the start of chemotherapy. No PCP occurred in the other 10 patients, and 10 patients with high-risk patients did not receive prophylactic administration. Five patients developed PCP, indicating that the preventive effect was Reliable, the pediatric department of 301 General Hospital improved the understanding of this disease after PCP in children with leukemia. In 1988, SMZco 20mg/(kg·d) was routinely administered in leukemia CR, divided into two oral doses per week. Even after taking a 4-day, 4-day prevention program, only one case of high-risk children who were predisposed to PCP was treated. This case was just a child who did not take SMZco, indicating that the same preventive effect can be achieved by 3 days of continuous therapy. It will not increase the infection rate and side effects of other pathogens, and it can greatly reduce the incidence of systemic fungal infections in patients. Precautions must be taken for patients with complete recovery of PCP. Otherwise, re-infection can occur. In adults, TMP cannot be tolerated. SM Z patients, alternative drugs are pentamidine, clindamycin / pyrimethamine; dapsone alone or in combination with TMP, pyrimethamine, widely used in AIDS or transplant patients; pyrimethamine and sulfadoxine Successfully used for the prevention of Pneumocystis carinii.
Complication
Complications of Pneumocystis pneumonia in children Complications pediatric acute respiratory distress syndrome
The complications of Pneumocystis carinii pneumonia are increasing, such as cystic lesions of the lungs, spontaneous pneumothorax, consolidation of the upper lobe, etc., and their performance changes rapidly and diversely. If they are not properly treated, they can rapidly develop into acute respiration. Distress syndrome. Acute respiratory distress syndrome refers to the serious pathological changes caused by diffuse injury of pulmonary capillaries and enhanced permeability. Pulmonary edema, hyaline membrane formation and atelectasis are the main pathological changes for progressive respiratory distress. And refractory hypoxemia is a clinically characterized acute respiratory failure syndrome.
Symptom
Pneumocystis pneumonia symptoms in children, common symptoms, vocal irritability, restlessness, convulsions, three concave signs, shortness of breath, diarrhea, nose flaps, difficulty breathing
1. Symptoms and signs can be divided into two types
(1) Infant type: mainly occurs in small infants from 1 to 6 months. It is an interstitial plasma cell pneumonia. The onset is slow. The main symptoms are poor feeding, irritability, cough, rapid breathing and cyanosis, and fever. Not significant, a small number of voices during auscultation, dyspnea gradually worsened within 1 to 2 weeks, less lung signs, and disproportionate to the severity of respiratory distress symptoms, one of the characteristics of this disease, the course of disease 4 to 6 weeks, if not About 25% to 50% of children die from treatment,
(2) Child type: mainly occurs in patients with low immune function caused by various reasons. The onset is rapid. Unlike other infants, almost all patients have fever. In addition, common symptoms are accelerated breathing, cough, cyanosis, and three concaves. Signs, nose fans and diarrhea, the course of disease develops rapidly, and more deaths when not treated,
2. X-ray examination shows diffuse granular shadows of the lungs, stretching from the hilum to the surrounding area, with ground glass, accompanied by bronchial inflatable images, which later become dense strips, with irregular patchy shadows, and lasting Emphysema, more prominent around the lungs, may be associated with mediastinal emphysema and pneumothorax.
Examine
Examination of pneumocystis pneumonia in children
1. Blood routine examination showed that the white blood cell count was normal or slightly higher, and more with neutrophils, lymphocytes decreased in about half of cases, and eosinophils increased slightly.
2. Other blood gas analysis showed significant hypoxemia and alveolar arterial oxygen pressure difference increased, NBT test was positive, sputum and tracheal smear pathogen examination were mostly negative, chest X-ray showed initial stage in the lung There are net-like, flocculent and strip-like blurred shadows around the door. As the disease progresses, small patches of blurry shadows and nodular shadows appear, which can also be merged into larger slab-like shadows. For multiple, pulmonary lesions generally develop from the two lungs along the bronchus to the outer periphery. The two lung tips and the lung base are rarely affected or affected less. This disease is characterized by the disease. If the lesion is close to the pleura, it may cause mild responsiveness of the local pleura. Thick, usually without pleural effusion,
Diagnosis
Diagnosis and identification of pneumocystis pneumonia in children
diagnosis
The diagnosis of PCP depends on the detection of pathogens. The most widely used is the fiberoptic bronchoscopy lung biopsy, percutaneous lung puncture or open lung biopsy and bronchoalveolar lavage fluid examination, the positive rate can reach more than 90%, relying on trachea Aspirate or lung biopsy section staining is seen in the alveolar foamy eosin substance mass is rich in protozoa, stained with urotropine silver nitrate, can be found in the diameter of 6 ~ 8m dark brown round or oval The cyst, located outside the cell, is stained with Toluidine blue, silver hexamethyleneamine, Grdm-Wright, Grimss and immunofluorescent antibody staining, etc., and people use high-salt saline inhalation to induce sputum to improve pathogen detection. In recent years, ELISA has been used to detect Pneumocystis IgG antibodies and latex microparticle agglutination tests to detect cysticercosis antigens, or molecular biology techniques such as PCR for rapid early diagnosis.
Differential diagnosis
The disease needs to be differentiated from bacterial pneumonia, viral pneumonia, fungal pneumonia, AIDS and lymphocytic interstitial pneumonia (LIP). Among them, LIP and this disease are more likely to occur in children with AIDS and are more difficult to identify. However, LIP is mostly chronic, with cough and lung dry sputum, with systemic lymph node enlargement and salivary gland enlargement. It is characterized by extensive pulmonary interstitial infiltration of mature lymphocytes in lung biopsy pathology.
