Fungal pneumonia in children

Introduction to pediatric fungal pneumonia Mycotic pneumonia (mycoticpneumonia) refers to lung infection caused by fungi and actinomycetes. It accounts for the first place in all visceral fungal infections. Although it is rare, it often occurs on the basis of many systemic diseases, which can cause diagnosis and treatment. Difficulties, so it has certain significance in clinical work. In the past 10 to 20 years, the widespread use of broad-spectrum antibiotics, cytotoxic drugs and adrenocortical hormones has been increasing in incidence and clinical importance. basic knowledge The proportion of illness: the probability of illness in infants and young children is 0.06% Susceptible people: children Mode of infection: non-infectious Complications: Thrush, atelectasis, proteinuria

Pediatric fungal pneumonia

Pathogens (30%):

The main deep mycosis diseases are candidiasis, aspergillosis, histoplasmosis, coccidioidomycosis, sporotrichosis, trichomycosis, pigmented fungal disease, cryptococcosis and blastomycosis, among which white Candida is the most common and most pathogenic. In addition, community-acquired pulmonary fungal infections have become a very serious problem, especially in the differential diagnosis of community-acquired pneumonia. Aspergillus is widely found in nature. It is the second human opportunistic fungal infection after Candida. The path of Aspergillus infection is mainly the respiratory tract. The lung is the most common lesion, and the pathogenic fungi play an important role.

Promoting factors (25%):

There are two main ways in which fungi can infect the respiratory tract. One is the primary inhalation infection; the other is conditional, and the factors that cause candidiasis are:

(1) Premature infants, newborns, malnourished children and debilitated children.

(2) Chronic wasting diseases such as malignant tumors.

(3) Reticuloendothelial diseases and immune diseases such as leukemia, agranulocytosis, and aplastic anemia that affect immune function.

(4) Metabolic disorders such as diabetes and renal failure.

(5) long-term use of adrenocortical hormone and other immunosuppressive drugs, causing low immunity.

(6) Defects in congenital immune function.

(7) Long-term use of broad-spectrum antibiotics inhibits the microbes that prevent Candida reproduction in the intestines, and makes the flora imbalance.

(8) Long-term application of intravenous high-nutrition patients.

(9) Infections in hospitals due to contaminated equipment (such as various catheters that are left in the long term).

(10) Acquired immunodeficiency disease (AIDS, AIDS), systemic disseminated candidiasis has been rare in the past. Currently, due to the increasing use of immunosuppressive drugs and intravenous high nutrition, chronic mucosal candidiasis can occur separately. Or seen in hypoparathyroidism or Addison patients.

Pathogenesis

Fungi can be parasitic on the skin, respiratory and digestive tract of normal people, and generally do not cause disease. However, when the flora of the child is dysregulated and the immune function is low, the bacteria may cause disease due to the proliferation of the bacteria. The infection is mostly endogenous. Taking the digestive tract as the main invasive route, the respiratory tract is the second, the primary lesion is mostly in the mouth (such as thrush), the infection can be self-venting, the pharynx spreads down and causes esophageal, gastric and small intestinal lesions, and can also cause respiratory diseases, or It can spread to the lungs through blood circulation; when the body is weak, the children with low immunity can inhale a lot of hyphae and spores, which can cause primary pulmonary fungal disease. The pulmonary aspergillosis is mainly secondary to tuberculosis and bronchiectasis. Pulmonary pus, pneumonia, pulmonary cysts or lung cancer, infants and children are rare, clinically seen allergic pulmonary aspergillosis, tissue erosive pulmonary aspergillosis and aspergillosis, the incidence of allergic pulmonary aspergillosis The mechanism belongs to type I and type II allergic reactions. It occurs mostly in individuals with specific reactivity and chronic asthma. The serum IgE and precipitated IgG antibodies are increased. The bacteria are present in grains, straw, spoiled plants, and soil. , Poultry and livestock in fur, aspergillosis mainly affects the lungs.

Mostly caused by inhalation of dust containing a large amount of Aspergillus spores in the respiratory tract. In general, inhaled Aspergillus spores are not necessarily pathogenic, but in tissue damage, inflammation or chronic disease, decreased body resistance or long-term application of broad-spectrum antibiotics, adrenal cortex Hormones and cytotoxic drugs, often cause disease, which is one of the reasons for the obvious increase in this disease in recent years. Aspergillus can cause 5 types of lower respiratory tract diseases: spore allergy, allergic lung disease, non-invasive saprophytic diseases (Aspergillosis), allergic bronchopulmonary aspergillosis and invasive aspergillosis, people with normal immune function are exposed to an environment in which a large number of Aspergillus spores are present for a long time, and when the number of inhaled spores exceeds the limit of the human defense system, It can also cause invasive pulmonary infections. Invasive pulmonary aspergillosis is more common in patients with impaired immune function caused by various causes. Infection can be invaded through the airway or invaded by blood vessels.

Pediatric fungal pneumonia prevention

1. Strictly control the indications, time and dose of broad-spectrum antibiotics, corticosteroids, cytotoxics, immunosuppressive drugs and antimetabolites.

2. Identify and treat focal fungal infections in a timely manner.

Pediatric fungal pneumonia complications Complications, thrush, atelectasis, proteinuria

Skin: Thrush, fungal skin infections.

Respiratory system: may have atelectasis, can be complicated by exudative pleurisy, respiratory failure can occur.

Nervous system: toxic encephalopathy and cerebral edema can occur.

Cardiovascular system: dysfunction, shock, easy to develop myocarditis, pericarditis; often with Reye syndrome.

Urinary system: manifested as hematuria, proteinuria.

Concurrent bacterial infection: common pathogens are Staphylococcus aureus, pneumococci, Haemophilus influenzae and hemolytic streptococcus. The lesion may be bronchial pneumonia, lobar pneumonia or lung abscess.

Symptoms of fungal pneumonia in children Common symptoms Low fever, irritability, restlessness, diarrhea, dyspnea, dyspnea, respiratory failure, pleural effusion, pericardial effusion

Often secondary to infant pneumonia, diarrhea, tuberculosis and blood diseases, the clinical manifestations of Candida albicans pneumonia are low fever, cough, shortness of breath, cyanosis, listlessness or irritability, older children can cough out colorless jelly samples Sputum, occasional bloodshot, chest signs including percussion dullness and auscultation breath sound enhancement, can have tubular breath sounds and small and medium bubble sounds, X-ray examination a bit of shadow, can be like miliary tuberculosis, and there are large solid lesions, a few have Pleural effusion and pericardial effusion, and may have oral thrush, skin or digestive tract fungal disease, in the lung can also be associated with drug-resistant staphylococci or Escherichia coli, Candida albicans pneumonia Similar to the clinical symptoms of invasive aspergillosis, initially with fever, cough and progressive dyspnea, the typical sign of vascular invasive aspergillosis on CT is a frosted glass halo ring, which is pathologically For hemorrhagic necrosis, and airway invasive aspergillosis is not specific, similar to bacterial, mycoplasmal, viral bronchitis or bronchial pneumonia, should be identified, vascular invasion Pulmonary aspergillosis may have atelectasis performance.

Examination of pediatric fungal pneumonia

Pathogen examination

(1) Culture of sputum or bronchial secretions and smear detection of fungi: about 10% to 20% of normal human sputum can also be found in this bacterium, must be distinguished by parasitic bacteria or pathogenic bacteria, Candida albicans Invasive mucosa can form pseudohyphae, so direct smear can be found in Candida spores and pseudohyphae, which can be used for diagnosis. Can be isolated and cultured in Saskatchewan glucose agar medium at 37 ° C incubator or room temperature. After cultivating for 3 to 5 days, it can be seen as milky white moist round or oval colony with special yeast aroma. If the number of colonies exceeds 50%, it has diagnostic significance. When transplanted on maize medium, branching can be seen. The characteristics of mycelium such as hyphae and thick-film spores can be obtained by culturing on agar agar medium at 37 ° C or room temperature to obtain milky yellow or brownish yellow colonies. Animal experiments confirmed that Cryptococcus caused disease, sputum or bronchial secretions in mice. Cryptococcus can be found in combination with clinical diagnosis of pulmonary cryptococcosis.

(2) Fungi detected in cerebrospinal fluid: In patients with clinical manifestations of meningitis, cerebrospinal fluid is taken for smear ink staining and culture to detect new cryptococcus, and after diagnosis of cryptococcal meningitis, the lungs should be examined simultaneously. In the lesion, 50% of cryptococcal meningitis patients can be detected by ink staining in the cerebrospinal fluid.

(3) Blood culture: especially in patients with low immune function, the blood culture has obtained fungi several times to help the diagnosis of disseminated cryptococcosis. Generally, blood culture is less positive, and if it is positive, it indicates serious infection. For those who have Candida albicans infection or Candida enteritis in the superficial parts of the body, the blood culture should be sent early and repeated, and the culture time should not be less than 4 weeks. The positive result has diagnostic value.

(4) Lung biopsy: It also helps to confirm the diagnosis. In case of severe cases, there is a large fusion lesion in the lungs. It can be used for lung puncture. The lung puncture fluid is used for culture and direct smear. It is found that the pathogen has a diagnostic significance.

(5) vaginal secretions: For neonatal patients, the mother's vagina should be checked for white candidiasis, and the newborn is swallowed or inhaled contaminated amniotic fluid by the birth canal.

(6) Enzyme-linked immunosorbent assay: Enzyme-linked immunosorbent assay for detection of Candida antigen in blood is helpful for diagnosis. The detection of Candida albicans by gas-liquid chromatography is highly sensitive and results can be obtained quickly.

(7) Skin test and animal test: fungal antigen skin test serological examination, animal inoculation, etc. can assist in diagnosis.

(8) PCR detection: PCR detection of highly conserved specific rDNA fragments of fungi is more sensitive than lactose measurement and latex agglutination test. In addition, stilbene compounds such as Calcofluor white, Blancophor and IJvitex have been used. Body fluids, tissue sections, smear and dandruff hair are fungal-stained to make the specimen emit blue-white or yellow-white light under ultraviolet light, which can improve the sensitivity of microscopic examination and increase the detection rate (up to 95%).

(9) Others: smear of urine, feces, secretions, pleural effusion, hydrocephalus, pus, etc., culture, tissue examination to find fungal spores and/or hyphae is an important basis for diagnosis, see typical The culture of mycelium and fungi is positive, and the fungal production rate of fungal culture medium is higher than that of standard bacterial culture medium. 2. Milk mannose is a polysaccharide antigen of Aspergillus, which can be used for early diagnosis of high-risk population, serum (13 --D-glucan is an important component of the fungal cell wall. It can be used not only for early diagnosis of deep fungal infections, but also for monitoring changes in plasma levels to prompt patients to respond to fungal treatments.

Film degree exam

X-ray examination chest radiograph is a bit shaded, can be like miliary tuberculosis, and there are large solid lesions, a few have pleural effusion and pericardial effusion, lung lesions are mainly distributed in the middle, lower, especially below, generally not Invasion of the lung tip, inductive lung X-ray performance has 6 types:

1 pneumonia type: a large piece of dense shadow, can involve multiple lung segments or lung lobe, a few segments are segmental changes.

2 bronchial pneumonia type: manifested as diffuse speckled and cotton-like shadows distributed along the bronchus, more common in two lower lungs.

3 lung abscess type.

4 inflammatory mass type.

5 Aspergillus ball X-ray changes are characteristic.

6 pleurisy type: a small number of children can be complicated by exudative pleurisy, the shadow changes greatly in a short period of time, one lung field shadow is reduced, the other shadow can be increased, acute blood line disseminated inflammatory fungal, X-ray examination Miliary shadows, diffuse nodular shadows or multiple small abscesses can be seen. If necessary, CT, B-ultrasound, electrocardiogram, etc. can be used.

Diagnosis and diagnosis of fungal pneumonia in children

diagnosis

In addition to the cause of the symptoms of pulmonary infection or pulmonary infection in areas prone to epidemics, those who are not treated with antibacterial therapy should consider the possibility of the disease. The diagnosis is mainly based on pathogenic examination, in which sputum, urine, feces, secretion Smear, pleural effusion, blood, brain effusion, pus, etc. smear, culture, tissue examination to find fungal spores and / or hyphae is an important basis for diagnosis, combined with clinical data can make a diagnosis, another fungal antigen skin test Serological examination, animal inoculation, etc. can assist in diagnosis. Histological examination shows typical hyphal and fungal culture positive, and fungal culture medium has higher fungal yield than standard bacterial culture medium.

Differential diagnosis

The clinical and X-ray findings of pulmonary mycosis are mostly non-specific, and are easily confused with common lung diseases such as tuberculosis, pneumonia, parasitic diseases, lung tumors, chronic bronchitis, etc. Airway invasive aspergillosis is not specific. Similar to bacterial, mycoplasmal, viral bronchitis or bronchial pneumonia, should be identified.

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