Cytomegalovirus pneumonia

Introduction to cytomegalovirus pneumonia Cytomegalovirus (CMV) is a viral pneumonia characterized by the formation of large type A eosinophilic intranuclear and intracytoplasmic inclusions in infected cells, most of which are asymptomatic latent infections, but with low immune function and Infants can cause severe lung infections and cause death. In recent years, with the development of bone marrow and organ transplantation and the increasing number of AIDS patients, CMV has become the most common pathogen in these two cases. basic knowledge The proportion of illness: 0.001% Susceptible people: no specific population Mode of infection: non-infectious Complications: multiple lung infections

The cause of cytomegalovirus pneumonia

(1) Causes of the disease

Cytomegalovirus belongs to group B herpesvirus and is a double-stranded DNA virus. It has a capsule and a nucleus. It has poor stability to heat and low temperature. It can be inactivated at 56 ° C for 30 min or 4 ° C for 1 week. It can also be UV-soluble and fat-soluble. Solvent inactivation, CMV has two antigens, complement-binding antigen and neutralizing antigen. The former exists mostly as soluble antigen, the latter is mainly composed of glycoprotein, which is one of the components of viral envelope, and CMV infection is strict. The specificity of the species, humans are only infected by human cytomegalovirus, the infected virus slowly grows and multiplies in the cells (2 to 3 months showing obvious lesions), the infected nuclei increase, the cytoplasm increases, forming a typical eosinophilic Intranuclear and cytoplasmic inclusion bodies.

(two) pathogenesis

CMV can be transmitted in a variety of ways. Infants and young children are mainly sexually transmitted. Adults are mainly sexually transmitted. The degree of infection depends on the number of exposed viruses and the immune status of the body. The main infections of CMV include distribution in epithelial cells and mesentery. Various immunocompetent cells, such as vascular endothelial cells, T cells, B cells, and NK cells, replicate in the body after infection, the volume of infected cells increases, the center is focal necrosis, and new synthetic is released. The virus further infects surrounding cells. The infected cells of the lung tissue are mainly alveolar cells and macrophages. After infection, diffuse pulmonary interstitial edema, fibrosis and alveolar swelling, focal necrosis, hemorrhage and hyperplasia, resulting in low Oxygenemia, because cellular immunity plays a major role in anti-CMV infection, the condition is particularly serious after CMV infection occurs in patients with cellular immunodeficiency (such as bone marrow transplantation and AIDS patients).

Cytomegalovirus pneumonia prevention

Because CMV infection is common in patients with bone marrow and organ transplantation, donor screening should be done before transplantation, and donors with negative CMV antibody should be selected as much as possible. For antibody-positive patients, preventive one week before surgery and one month after surgery. Acyclovir was used, and immunoglobulin infusion with high-priced CMV antibody was used to increase passive immunity 1 day before and 2 weeks after transplantation to prevent passive immunity after every 3 weeks to 100 days after surgery. The occurrence of CMV pneumonia.

Cytomegalovirus pneumonia complications Complications multiple lung infections

Severe lung and systemic infections often occur.

Symptoms of cytomegalovirus pneumonia Common symptoms Two lungs glassy millet... Breathing difficulties Respiratory failure snoring toxemia hemoptysis with skin and mucous membrane bleeding interlobular often curved arc drop alveolar hemorrhage

Most of the CMV-infected patients with good immunity are asymptomatic and concealed, and thus become the source of CMV infection in bone marrow and organ transplant recipients. Therefore, it is very important to perform CMV serological examination on donors before transplantation. There are two clinical manifestations of cytomegalovirus pneumonia:

Rapid advance

From January to February after transplantation, fever, cough, discomfort, difficulty in breathing, decreased activity, hypoxia and respiratory failure; pulmonary auscultation has no signs, and patients with bacterial or fungal infections can hear the voice, and the disease progresses rapidly. It can rapidly deteriorate and die; the X-ray of the lung is mainly characterized by multiple miliary nodules in both lungs, with a diameter of 2 to 4 mm. The autopsy pathology shows diffuse alveolar hemorrhage, fibrosis and neutrophil response, which are common in primary infection. There is no specific antibody in the body, so the incidence is acute and heavy, which is easy to cause systemic viremia and secondary bacteria and fungal infection.

2. Slow-moving type

Three to four months after transplantation, the symptoms were similar to the rapid progression, but the progress was slow, the symptoms were mild, and the mortality was low. The lung X-ray showed diffuse interstitial pneumonia, fibrosis; the pathological manifestation was alveolar interstitial edema. Different degrees of fibrosis, lymphocytic infiltration and epithelial cell proliferation are common in CMV reinfection or latent viral activation.

CMV pneumonia in AIDS patients is non-specific, often combined with systemic CMV infection, such as retinitis, colitis, cholangitis and esophagitis, chest X-ray and CT common two-lung ground-glass, miliary or nodular changes, blood routine suggesting surrounding white blood cells Decline.

Because of the similarity in the clinical manifestations of viral pneumonia, pathogenic examination is particularly important. The pathogen examination of CMV can be carried out in the following aspects:

1 detection of CMV inclusion body cells and virus particles: such as from the patient's blood, urine, and bronchial lavage, but there is a higher false positive, 71% to 91% of high-risk transplant patients from the BAL, although CMV is isolated, However, there is no evidence of active pneumonia. It is also possible to isolate the various secretion samples of the patient in vitro after being inoculated into human embryos or fibroblasts, but it usually takes 2 weeks to 2 months to confirm the diagnosis;

2 immunological methods: the CMV antigen in patients and donor secretions can be measured by fluorescent or enzyme-labeled antibodies, which is beneficial for early diagnosis and screening of donors before transplantation, and can also be used for antibody in serum by complement binding assay. Dynamic detection, in the acute phase and recovery period, the serum antibody titer was more than 4 times positive;

3 molecular biological methods: such as PCR technology and nucleic acid hybridization, the former is mainly used for the detection and dynamic monitoring of BAL, the latter is often used for the detection of pathological sections of lung tissue, and can distinguish between different subtypes of viruses. .

Examination of cytomegalovirus pneumonia

blood test

Peripheral white blood cells are reduced, and cytomegalovirus, respiratory secretions and fiberoptic bronchoscopes can be isolated by inoculating respiratory secretions, saliva, urine, cervical secretions, liver and lung biopsy specimens into human embryonic fibroblast culture medium. The giant cells in the eosinophilic nucleus inclusions are found in the lung biopsy specimens, which can be diagnosed.

Serum cytomegalovirus antibodies are measured, and when the serum antibody is increased by 4 times or more, it is helpful for diagnosis.

Chest X-ray

Mainly manifested as diffuse interstitial or alveolar infiltration of the two lungs, very few can be nodular shadows, occasionally signs of pleural effusion, lung consolidation suggestive of bacterial or fungal infections.

Pathogen examination

The pathogen examination of CMV can be carried out in the following ways:

1 Detection of CMV inclusion body cells and virus particles: if isolated from patients' blood, urine, and bronchial lavage, but there is a high false positive, 71% to 91% of high-risk transplant patients from CAL, although CMV is isolated, But there is no evidence of active pneumonia. The patient's various secretion samples can also be isolated and cultured in vitro after being inoculated into human embryos or fibroblasts, but it usually takes 2 weeks to 2 months to be diagnosed.

2 Immunological methods: CMV antigens in patients and donor secretions can be measured by fluorescent or enzyme-labeled antibodies, which facilitate early diagnosis and screening of donors before transplantation. The antibodies in the serum can also be dynamically detected by a complement-binding assay, and the serum antibody titers in the acute phase and the recovery phase are more than 4 times positive.

3 molecular biological methods: such as PCR technology and nucleic acid hybridization, the former is mainly used for the detection and dynamic monitoring of BAL, the latter is often used for the detection of pathological sections of lung tissue, and can distinguish between different subtypes of viruses. .

Diagnosis and diagnosis of cytomegalovirus pneumonia

Should be distinguished from other diseases: such as other viral pneumonia (respiratory syncytial virus, influenza, parainfluenza or enterovirus), Pneumocystis carinii and Chlamydia lung infection.

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