Chlamydia pneumonia in children

Introduction to pediatric chlamydia pneumonia Chlamydialpneumonia refers to acute lung inflammation caused by Chlamydia, a class of intracellular parasitic prokaryotic microorganisms, mainly Chlamydia trachomatis (CT), Chlamydia pneumoniae (CPN), Chlamydia psittaci (CP) and There are four types of poultry chlamydia, the first three related to humans, which can cause pneumonia and multiple systemic damage outside the lungs. basic knowledge The proportion of illness: the probability of illness in infants and young children is 1.2% Susceptible people: children Mode of infection: respiratory transmission Complications: myocarditis, pleurisy, pleural effusion, anemia

Pediatric chlamydia pneumonia

Causes

Chlamydia infection (38%):

Chlamydia is divided into four types: Chlamydia trachomatis (CT), Chlamydia pneumoniae (CPN), Chlamydia psittaci (CP), and Chlamydia pecorum. Chlamydia is a bacterium but has a virus characteristic. It seems that the bacteria have a cell wall, the same way of reproduction and division, there are DNA and RNA; the virus seems to grow only in the cell. Common chlamydia causing pneumonia are CT and CP.

Infection of the birth canal (20%):

Chlamydia trachomatis infection is one of the most common sexually transmitted diseases in developed countries, and can also cause non-gonococcal urethritis or cervicitis, pelvic inflammatory disease. Vertical infection of infected mothers can cause conjunctivitis or Chlamydia trachomatis pneumonia in infants. Foreign reports of 1/4 of hospitalized infants with lower respiratory tract infections under 6 months are CT infections. Domestic studies have confirmed that CT pneumonia accounts for 18.4% of infant pneumonia and is an important cause of infant pneumonia.

Pathogenesis

Chlamydia has been assigned to Rickettsia in the past and is now an independent genus. Chlamydia is parasitic in host cells, but unlike viruses, it has cell walls and contains DNA and RNA. CT is the main cause of pneumonia in infants under 6 months. One of them is mostly transmitted by infected mothers through the birth canal. Chlamydia pneumoniae is a new chlamydial species found in the mid-1980s. It is a strict human pathogen. There is no animal intermediate host, which mainly causes human acute respiratory tract. Infection, especially pneumonia, is one of the causes of pneumonia in children and adults over 5 years old. Chlamydia psittaci mainly parasitizes parrots and their birds and lower mammals. People are exposed to or inhaled by bird droppings or secreted by birds. The disease is contaminated by feathers and is rarely transmitted from person to person. Chlamydia pneumoniae is mainly transmitted through human respiratory secretions. It is not clear about the pathogenesis and pathological changes of human respiratory tract chlamydia pneumoniae infection. Chlamydia trachomatis infection way:

1 The fetus is directly infected through the mother's birth canal.

2 The eye is infected with chlamydia and invades the respiratory tract through the nasolacrimal duct. After invading the respiratory tract, the Chlamydia psittaci invades the liver, the spleen and other reticuloendothelial cells, and after being propagated in the mononuclear and phagocytic cells, the blood is spread to the lungs and other organs. In the lung caused by lobular or interstitial pneumonia, bronchiolitis and bronchial epithelial cell desquamation and necrosis, lesions can produce consolidation and a small amount of bleeding, pulmonary interstitial lymphocytic infiltration, hilar lymph nodes can be swollen, liver Local necrosis may occur, the spleen often enlarges, and the heart, kidney, nervous system, and digestive system may be involved.

Pediatric chlamydial pneumonia prevention

1. The disease should be diagnosed and treated during pregnancy. The daily dose of erythromycin 1g in the late pregnancy can last 2 weeks, which can prevent the incidence of CT pneumonia in infants. Reasonably take effective antibiotics, and seek to cure as soon as possible to prevent the disease from prolonging and turn into chronic or long-term carriers.

2. Pay attention to collective and personal hygiene, and strengthen the management and supervision of environmental public health.

3. There is currently no vaccine.

Pediatric chlamydia pneumonia complications Complications Myocarditis pleurisy pleural effusion anemia

Can be complicated by myocarditis, pleurisy, pleural effusion, encephalitis, anemia, reactive hepatitis, DIC and so on.

Pediatric Chlamydia pneumonia symptoms Common symptoms Nasal lymph node enlargement Protein urinary snoring snot nose drowsiness Chest pain Low heat hoarseness and abdominal pain

Insidious onset, generally no fever, only mild respiratory symptoms, such as salivation, stuffy nose, cough, cough can be sustained and gradually worsened, there is a pertussis-like cough, but no echo. Breathing is a typical symptom, occasionally apnea or expiratory wheezing, and you can smell the wet sounds or wheezing sounds of both lungs. Even pleural effusion can occur, and half of the patients can see conjunctivitis and abnormal appearance of the tympanic membrane. Peripheral blood seems to have an increase in eosinophils. Blood IgM, IgG and IgA were both increased. PaO2 is lowered but PaCO2 is normal. Lung biopsy showed necrotic bronchiolitis and alveolar consolidation. The course of the disease is prolonged, often for several weeks, and can be self-healing.

History

When Chlamydia trachomatis pneumonia, there is often a history of mother infection and a history of conjunctivitis, which is more common in small babies. Parrot fever pneumonia often has a history of exposure to pathogens and their pollutants. Chlamydia pneumoniae pneumonia is more common in older children, and more history of disease-free poultry exposure.

2. Clinical manifestations

(1) Chlamydia trachomatis pneumonia: more common in small infants within 3 months, especially about 3 weeks after birth. Generally, there are upper sensations such as salivation, nasal congestion, etc., no fever or low fever, followed by coughing, pertussis-like cough, but no echo, rapid breathing is a typical symptom, occasionally apnea. Wet snoring can occur in the lungs, sometimes with exhalation wheezing. May be associated with myocarditis, pleurisy, pleural effusion, 50% with inclusion body conjunctivitis and abnormal appearance of the tympanic membrane. The course of the disease is delayed, often for several weeks.

(2) Chlamydia pneumoniae pneumonia: more common in older children, the onset is slower. From the beginning, there are symptoms of upper sensation, often accompanied by sore throat, hoarseness and fever. Followed by the increase in cough, and lasts for a long time, more than 3 weeks, a small number may be associated with myalgia, chest pain and so on. The signs of the lungs are often not obvious, and dry and wet voices can be heard. Often accompanied by lymphadenopathy, but also combined with otitis media, sinusitis and Streptococcus pneumoniae infection. In recent years, it has been found that, in addition to causing respiratory diseases, Chlamydia pneumoniae can cause diseases other than respiratory diseases such as myocarditis and encephalitis.

(3) Chlamydia pneumonia: more common in older children and adults. The onset is more insidious, and when the condition is mild, it is a transient flu-like symptom. Can also acute onset, chills, headache, sore throat, fatigue, fever, body temperature can be as high as 40 ° C, relatively slow pulse, cough, cough a small amount of sticky or bloody, and can appear nausea, vomiting, abdominal pain and other gastrointestinal symptoms. Children may have neuropsychiatric symptoms such as lethargy, convulsions, and convulsions. There are no obvious signs in the lungs, and even the wet sputum can be heard. In severe cases, there may be signs of lung consolidation. In addition, there may be endocarditis, anemia, reactive hepatitis, hepatosplenomegaly, proteinuria, nodular erythema, DIC, and the like.

Examination of pediatric chlamydia pneumonia

Pathogen examination

Nasopharyngeal swab smear for Giemsa staining showed that the pathogen was iodine-infected intracytoplasmic inclusions, and the sensitivity to diagnosis was only about 35%. Cell culture was used for pathogen isolation. It is considered that McCoy cells are cultured and stained with fluorescent antibody. The gold standard has a sensitivity of 70% to 80% and a specificity of over 90%.

2. Serological examination

A single serum CT or CPN was measured by micro-immunofluorescence, specific IgMCT-IgM1:64, CPN-IgM1:16 or CPN-IgG1:512 or double serum test antibody titer increased 4 times, Prompt acute infection, such as IgG 1:16 but < 1: 512, suggesting previous infection.

3. PCR detection specific DNA PCR method is fast, simple, sensitive and specific.

4. X-ray inspection:

CT pneumonia: diffuse interstitial lesions and patchy lung infiltration with emphysema.

CPN pneumonia: mostly unilateral segmental infiltration, more common in the lower lobe and surrounding, a few may have bilateral lesions, severe cases may be associated with pleural effusion, lung signs and X-ray findings often disappear after more than 1 month , Chlamydia psittaci pneumonia manifests as an infiltrating lesion radiated from the hilar, often invading the lower lobe of the lungs, showing diffuse interstitial pneumonia or bronchial pneumonia, occasionally miliary nodules or solid lesions, or Symptoms of pleural effusion.

Diagnosis and diagnosis of chlamydia pneumonia in children

diagnosis

Diagnosis can be based on medical history and related symptoms.

Differential diagnosis

It should be differentiated from viral pneumonia, bacterial pneumonia and mycoplasmal pneumonia. When pneumonia cannot be explained by bacteria, virus or mycoplasma infection, and the treatment with penicillin and cephalosporin is not effective, the possibility of chlamydial infection should be considered. Chlamydia antigen and serological examination, especially in small infants with a fever pneumonia within 6 months, should consider the disease.

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