Socially acquired pneumonia

Introduction to socially acquired pneumonia Community acquired pneumonia (CAP) is caused by a variety of microorganisms such as bacteria, viruses, chlamydia and mycoplasma outside the hospital. The main clinical symptoms are cough, with or without cough and chest pain, and a severe lung disease that is increasingly valued by medical circles around the world due to seasonal and geographical differences. Prodromal symptoms mainly include symptoms of rhinitis-like symptoms or upper respiratory tract infections, such as nasal congestion, nasal flow, sneezing, dry throat, sore throat, pharyngeal foreign body sensation, hoarseness, headache, dizziness, eye swelling, tearing and lightness. Cough and so on. Not every patient with acquired pneumonia has prodromal symptoms, and the incidence varies from 30% to 65% depending on the pathogen. Moreover, the incidence of morbidity is now rising rapidly and is also a research hotspot. It is important to take comprehensive preventive measures for socially acquired pneumonia. For patients with chronic diseases, due attention should be paid to strengthening nutritional support therapy, improving host defense mechanisms, and enhancing host immune function. For non-host factors, pay attention to limiting exposure to the population in the flu epidemic; in the risk population, use the most effective anti-influenza A virus drugs such as amantadine, or amantadine. Passive immunotherapy, such as intravenous immunoglobulin, can also be used to reduce the risk of bacterial infection; for example, gamma-globulin is prevented by low dose. In short, prevention of socially acquired pneumonia is an important and effective method. basic knowledge Sickness ratio: 1-5% Susceptible people: no special people Mode of infection: respiratory transmission Complications: atelectasis, lung abscess, myocarditis, shock, pulmonary edema, respiratory failure, meningitis

Causes of socially acquired pneumonia

Bacterial infection (80%):

The pathogens of socially acquired pneumonia mainly involve bacteria, mycoplasma, chlamydia and viruses. For bacterial pathogens, socially acquired pneumonia, in addition to tuberculosis and Legionella, can directly inhale bacteria into the lung parenchyma through droplets. The bacterium can be directly settled outside the trachea, and the rest are obtained by inhaling infectious agents from the autologous throat. The most common bacterial pathogens of socially acquired pneumonia are Streptococcus pneumoniae, Mycobacterium tuberculosis, Haemophilus influenzae. , Staphylococcus aureus, Legionella, Klebsiella and catarrha, etc., socially acquired pneumonia virus disease original A, influenza B virus, type 1, 2, 3 influenza virus, respiratory tract Cytoviruses and adenoviruses, other microbial diseases, such as Mycoplasma pneumoniae, Chlamydia pneumoniae and Chlamydia psittaci.

The results show:

1. In terms of bacteria, socially acquired pneumonia is the opposite of hospital-acquired pneumonia, mainly caused by Gram-positive bacteria, of which Streptococcus pneumoniae is the most common, and its positive rate accounts for 40% to 60% of known pathogens. , followed by Mycobacterium tuberculosis and Staphylococcus aureus.

2.80% of the pathogens are single consistent bacteria, 20% have two or more pathogens, and some pathogens can be detected in some tuberculosis patients, which may indicate that the original symbiotic bacteria may become pathogenic bacteria in tuberculosis patients.

3. Some patients with severe social acquired pneumonia often occur in people over the age of 60 and have certain underlying diseases such as diabetes and chronic obstructive pulmonary disease. These patients have a large proportion (20% to 30%). Lan negative bacilli. In the young population, the pathogens of bacterial pneumonia outside the hospital are different, and most of them are mainly Gram-positive bacteria.

4. The number of patients who have no pathogen basis in hospitalized socially acquired pneumonia is 30% to 50%, which may be due to the use of antibiotics before admission or due to incomplete testing methods currently used.

Pathogenesis:

There are three sources of pathogenic microorganisms that cause socially acquired pneumonia. One is to directly inhale the infected particles in the surrounding air, the other is to inhale the microbes in the mouth, nose, throat and throat, and the third is to wear the pathogens in the adjacent infected lesions. Transmitted or disseminated to the lung tissue, the first case mainly occurs in close contact with certain respiratory infection sources or in the epidemic area during a certain respiratory pathogen epidemic, the third case is less common, such as underarm abscess Breaking through the diaphragm to the right lung or Staphylococcus aureus sepsis blood intrapulmonary dissemination, etc., the second most common clinical situation, the upper respiratory tract normal flora is mainly mixed by a variety of aerobic bacteria, such as Streptococcus , Staphylococcus, Streptococcus pneumoniae, Neisseria (including Neisseria meningitidis), Diphtheria-like bacillus, Haemophilus, a small number of healthy people can also have Gram-negative bacilli parasitic, such as Escherichia coli, patina Monocytogenes, Klebsiella pneumoniae, Lactobacillus, Clostridium and rare spirochetes and Candida albicans, in addition, there are a large number of anaerobic bacteria parasitic in the teeth and gums, which are sprinkled per milliliter The bacterial concentration may be as high as 108.

Other pathogenic microorganisms that cause socially acquired pneumonia are distributed in nature or in some animals. Legionella is a common environmentally-contaminated bacteria that spreads mainly through the mist of contaminated water. Fungi are widely distributed in tropical and subtropical areas. In the natural world, spores fly into the respiratory tract with dust. Mycoplasma is widely distributed in nature and can also be parasitic on the human body. However, it is not caused by illness. Acute patients are the source of infection. Inhalation of droplets through the respiratory tract can infect others and cause pneumonia. There are two kinds of rickettsia in the clinic. One is the rickettsia, and the other is the rickettsia. The former causes Q fever pneumonia. The cattle and sheep are the main source of infection. After the pathogen is discharged from the automatic object. It is in an aerosol state, mainly inhaled into the human body from the respiratory tract. The latter causes typhus rickettsia pneumonia, which is mainly caused by human skin bite or skin lesions invading the human body. In the case of Chlamydia microorganisms, the past It is only known that Chlamydia psittaci can cause interstitial pneumonia in humans. In 1986, Grayston first discovered Chlamydia pneumoniae, which is different from Chlamydia trachomatis and Chlamydia psittaci, the main difference is that the outer membrane protein of Chlamydia pneumoniae has fewer antigenic determinants, is a non-immune dominant antigen when infected, and is the only known host, 8-9 years old and older than 70 years old. The elderly are the two peaks of infection, and the clinical manifestations are the same as those of parrot pneumonia, but 70% to 90% are subclinical. The serum samples of 2000 patients with pneumonia are found to have an infection rate of 8% and annual incidence. 1, the population over 70 years old is 3.

Various pathogenic microorganisms may not cause disease even if they accidentally enter the lungs. There must be two conditions to cause pneumonia. First, the pathogen itself must have sufficient survival quantity and virulence intensity. Second, the pathogen must overcome the body, especially The local immune defense function of the respiratory system mainly includes the anatomical barrier and clearing function of the nasopharynx and upper respiratory tract, and the immune clearance function of the cells and body fluid factors of the terminal gas exchange unit. This defense function can make the first lung of the normal lung. The bronchus remains below the bronchial level.

The upper respiratory tract and the atmospheric tract can be discharged by means of mechanical principles, including:

1 Anatomical barrier effects, such as tight junctions between epiglottis and mucosal surface cells.

2 glottis is reflectively closed.

3 The bronchial tree is frequently bifurcated, and the inhaled gas can be filtered by aerodynamic changes.

4 mucociliary clearance system to remove particulate matter from the mucosa.

5 cough reflex, when the source of infection, especially the bacteria escape the above-mentioned defense mechanism and enter the alveoli, another set of defensive functions play a role, the terminal unit (alveolar duct and alveolar) without ciliated epithelium and mucus secreting cells (cupomyocytes and Mucous gland), at this time cough can not effectively remove the pathogens entering the alveoli, mainly rely on phagocytic cells and body fluid factors to clear.

Conditioner: Most bacteria are rapidly digested by phagocytic cells after they reach the surface of the alveoli. Although alveolar macrophages have strong phagocytosis to inert particles, phagocytic bacteria are slower, coated or conditioned microorganisms can Increases phagocytosis by 10 times, the non-immune opsonin in the liquid layer on the alveolar surface (lipoprotein surfactant secreted by type II alveolar epithelial cells and local alveolar macrophages or angiogenically generated large fractions: daughter glycoproteins and fibers Immunomodulatory agents, including IgG antibodies and complement factor C3b, enhance the attachment of specific serosal receptors that can be produced locally or as part of whole body fluid immunity.

IgG and its subtypes are present in bronchoalveolar lavage fluids in a similar proportion to blood. IgG subtypes include: capsular polysaccharide antibodies in respiratory pathogens (eg, Streptococcus pneumoniae, Haemophilus influenzae) , phospholipid antibodies in staphylococci and lipopolysaccharide antibodies in Gram-negative bacilli, IgG1, IgG4 subtype, IgG3 in the macrophage FC gamma receptor, argyrophilic or adherent to the plasma membrane of alveolar macrophages At most, IgG1, IgG2, and IgG4 receptors are less and are often covered.

In the airway, the complement system can be activated by an alternative pathway, which dissolves the susceptible microorganisms and produces the opsin C3b. At the beginning of the phagocytic activity, the intracellular bactericidal process begins, but the rate is usually more nucleated, the leukocytic is slow, and may be aerobic dependent. And oxygen-independent two pathways involved, macrophages are different from polymorphonuclear leukocytes, usually lacking myeloperoxidase, but "activated" can make superoxide anion and hydrogen peroxide (H202 ) produces an increase.

Alveolar macrophages have the following characteristics in defense:

1 directly phagocytose pathogenic microbe particles into the alveoli.

2 can further inhibit, destroy the pathogen and finally kill it.

3 can survive for several days to several months, and can cope with repeated infection of pathogenic microorganisms.

4 has a migratory nature, can quickly move from the Kohn hole to other alveoli, or to the distal end of the respiratory tract.

5 can guide the intracellular degradation of antigenic substances and present them to specific lung lymphocytes to initiate a specific immune response.

6 can enter the lymphatic tissue of the respiratory bronchiole, transported by the lymph that produces humoral and cellular immunity.

Many of the active substances secreted by 7 are involved in the immune effect system and are involved in the formation of chronic inflammation and fibrosis or granuloma.

Lymphocytes recovered from normal alveoli account for about 10% of the total number of airway cells, 70% of which are T lymphocytes. The proportion of major lymphocyte subsets is similar to that of peripheral blood. Activation and inflammation of alveolar macrophages by lymphocytes It plays an important regulatory role and can directly participate in the formation and regulation of antibody responses, activate dormant toxic lymphocytes, and assist a small fraction (7%) of HLA-DR positive lymphocytes in T lymphocytes, which is the main component of interleukin-2. Source, killer T cells may be dormant cells, but can be activated by -interferon, T cells secrete several cytokines, including -interferon and macrophage inhibitors, which can activate macrophages, macrophages to inhibit Or killing certain microbes in cells must involve acquired cellular immunity, including Mycobacterium tuberculosis, Legionella, Pneumocystis carinii, Listeria monocytogenes and cytomegalovirus.

Pneumonia caused by various pathogenic microorganisms has roughly similar basic pathological changes, especially in the early stage of inflammation, and the procedures and contents of pathological changes are basically the same. These early basic pathological changes include: when initially attacked by pathogenic microorganisms Local tissue cell swelling, degeneration, necrosis, congestion, expansion, opening of adjacent microvessels, migration of intracellular cellular components and exudation of body fluid components, formation and involvement of various inflammatory cells and inflammatory mediators, in the later stages of the inflammatory process, Tissue and cell proliferation, repair and healing processes are also basically similar. In addition to the above-mentioned basically the same pathological features, different pathogenic microorganisms have different characteristics in terms of inflammation characteristics, extent of damage, degree of damage and healing results. Characteristics, such as bacterial pneumonia represented by Streptococcus pneumoniae, is characterized by fibrinous inflammation, which can invade a lung segment or even the entire lung. The main lesions occur in the alveoli, but there are no alveolar walls and other lungs during the whole lesion. Destruction or necrosis of the tissue structure, after the inflammation has dissipated Completely back to normal tissue can be left without fibrous scar, nor emphysema, but the same bacterial pathogen.

If it occurs in children, the elderly, and patients with various physical defenses such as debilitating or prolonged illness, it is easy to form suppurative necrotic inflammation of the lung tissue centered on the bronchioles, which is commonly seen in bronchopneumonia. Or lobular pneumonia, Staphylococcus, Streptococcus, pathogenic weaker Streptococcus pneumoniae, and Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, anaerobic bacteria, etc. More common, the pathological changes of viral pneumonia are characterized by early or mild viral pneumonia with interstitial pneumonia as the main manifestation, advanced or more serious viral pneumonia can further develop and affect the alveolar space, but still non-suppurative, only Some severely infected viral pneumonia (mainly seen in adenovirus pneumonia and measles virus pneumonia) may have pathological changes of suppurative necrosis. The pathological changes of fungal pneumonia are characterized by coagulative necrosis, cell infiltration, and suppuration in the acute phase. Stage is pulmonary fibrosis and granuloma formation, mycoplasma pneumonia is non-suppurative of the pulmonary interstitial: inflammation, lymphocytes and monocytes-based inflammation The cells infiltrate the alveolar wall of the alveolar wall and the interstitial. The lesions often do not exceed one lung segment. The pathological changes of rickettsial pneumonia are mainly caused by swelling, hyperplasia and necrosis of pulmonary interstitial vascular endothelial cells, and extensive perivascular inflammation. Thrombotic vasculitis and nodular changes, pathological changes of chlamydia pneumonia often begin in the hilar, and spread to the surrounding area to cause lobular and interstitial pneumonia, early alveolar neutrophils and edema exudate, soon That is replaced by monocytes.

Social acquired pneumonia prevention

It is important to take comprehensive preventive measures for socially acquired pneumonia. Patients with chronic diseases should pay due attention to strengthening nutritional support therapy, improving host defense mechanisms, and enhancing host immune function, such as annual influenza vaccine or pneumococcal vaccine. It is effective against 85% to 90% of bacterial infections, and its antigen induces the production of specific antibodies to increase the conditioning effect, phagocytosis and leukocyte, pneumococcal action of other phagocytic cells, pneumonia vaccine intramuscular or subcutaneous injection 0.5ml each time, right Host factors, pay attention to limit exposure to the population in the influenza epidemic; in the risk group, the most effective anti-influenza A virus drugs such as amantadine, or amantadine similar drugs, can also be used passive immunotherapy Intravenous immunoglobulin can reduce the risk of bacterial infection; such as -globulin: 400mg per kilogram of body weight, intravenous injection, once every 3 weeks, or 500mg per kilogram of body weight, or 250mg, once every 4 weeks, but the effect There is no difference, and low-dose prevention is appropriate. In short, prevention of socially acquired pneumonia is an important and effective method.

Socially acquired pneumonia complications Complications atelectasis, lung abscess, myocarditis, shock, pulmonary edema, respiratory failure, meningitis

Common complications are: atelectasis, lung abscess or empyema, less common complications are toxic myocarditis, toxic shock, pulmonary edema, respiratory failure, renal insufficiency, encephalitis, meningitis, drug fever and Long-term use of a large number of broad-spectrum high-efficiency antibiotics caused by double infection and dysbacteriosis.

Symptoms of socially acquired pneumonia Common symptoms Hernia, nausea, arm pain, reversal, nasal congestion, shortness of breath, leukocytosis, sepsis, dyspnea, dyspnea

1. Prodromal symptoms: The pre-existing symptoms of socially acquired pneumonia are higher than the incidence of acquired pneumonia in hospitals. They often occur in the early stage of pneumonia. A considerable number of patients have clear causes of cold or excessive fatigue. The prodromal symptoms mainly include rhinitis-like symptoms. Or symptoms of upper respiratory tract infections, such as nasal congestion, nasal flow, sneezing, throat, sore throat, pharyngeal foreign body sensation, hoarseness, headache, dizziness, eye swelling, tearing and mild cough, etc., not every one Patients with socially acquired pneumonia will have prodromal symptoms, and the incidence will be between 30% and 65% depending on the pathogen.

2. Systemic toxemia performance: Most patients with socially acquired pneumonia will have systemic toxemia-like symptoms, such as chills, chills, fever, dizziness, headache, body muscles and joint pain, body deficiency, Poor diet, nausea, vomiting, and mental illness can also occur in critically ill patients.

3. Respiratory symptoms: cough, cough, hemoptysis, chest pain, dyspnea, five major symptoms, the incidence of the above five major symptoms and their characteristics are different in different pathogens and different patients, and not every patient or every A pneumonia caused by a pathogen will have the above five symptoms at the same time. For example, mycoplasmal pneumonia often shows dry cough, and severe sternal pain. Viral and plasma cell pneumonia can gradually increase, but chest pain and shortness of breath are less. See, young people often appear as typical acute symptoms, while elderly or critically ill patients have cough, less cough, and often no obvious respiratory symptoms. The early stage of pneumonia in immunodeficiency patients can only manifest as increased respiratory rate, fever, and restlessness. There is no obvious respiratory symptoms, typical pneumococcal pneumonia can cough rust, sputum staphylococcal pneumonia has cough and blood stasis, Klebsiella pneumonia patients with cough can be brick red, Pseudomonas aeruginosa pneumonia Can be light green, anaerobic pneumonia patients can cough and sputum sputum, due to the widespread use of antibiotics in recent years, the current clinical The community-acquired pneumonia in patients with upper respiratory symptoms to light or not typical for many.

4. Extrapulmonary symptoms: In addition to directly causing respiratory symptoms, pneumonia may also have extrapulmonary symptoms. For example, the tip of the lung may reflect shoulder and arm pain. The posterior lesion may stimulate the pleura to show low back pain, and a few lower leaves. Lung infection can cause upper abdominal pain and radiation to the shoulder. It can also have hernia and hiccup. Systemic toxemia can be more prominent in a certain system, such as severe headache, nausea, vomiting and the mentality of critically ill patients. Obstacles and mental symptoms are significant. Although the incidence of extrapulmonary symptoms is not high, it is easy to divert people's attention and misdiagnosis. It should be paid attention to in diagnosis and differential diagnosis.

5. Complications: Complications of socially acquired pneumonia are rare, especially in recent years, with the application of a large number of powerful broad-spectrum antibiotics, the frequency of complications continues to decline, but it has not completely disappeared. Clinically still visible pleurisy or empyema, meningitis, pericarditis, endocarditis, peritonitis, early dissemination of menstrual blood can also cause arthritis, mastoiditis, otitis media, sinusitis, severe or sepsis patients can also The combination of shock and multiple organ failure can not be ignored by clinicians. On the other hand, due to the application of a large number of broad-spectrum antibiotics, some rare complications have been produced in the past, such as secondary virus infection, weak virulence conditions. Infection, as well as dysbacteriosis double infection and drug-resistant strain infection, are new problems that we must face. Therefore, while we pay attention to the symptoms of pneumonia itself, we must not miss the existence of complications, especially in After a regular anti-infective treatment in accordance with the pathogen, if the body temperature does not drop, or after the fever retreats, or if the symptoms are aggravated, the number of white blood cells is increased, etc., Into account the possibility of complications.

6. Pulmonary signs: The clinical signs of socially acquired pneumonia vary according to the location, size and course of the disease, and whether there are complications. The common signs are as follows:

1 general signs: such as high body temperature, acute fever, shortness of breath or difficulty breathing, severe patients may have a change in consciousness.

2 lungs physical signs: such as the side of the chest breathing exercise weakened, increased vocal fibrillation, diarrhea, vomiting, decreased breath sounds, enhanced speech transmission, tube-like breath sounds and inspiratory wet sounds.

3 extrapulmonary signs: such as cyanosis, mild jaundice, abdominal distension, upper abdominal tenderness, herpes simplex, etc. These signs are relatively rare clinically.

4 signs of complications: depending on the specific type of complications.

7. Clinical manifestations: The diagnosis of socially acquired pneumonia is not difficult. It is generally considered that like other pneumonia, patients have fever, newly developed cough, purulent sputum, leukocytosis or decrease; chest X-ray films have flaky, leafy High-density infiltrative lesions such as alveoli, more than half of patients older than 65 years have symptoms other than respiratory tract, more than one-third of patients have no signs of systemic infection, and most of them can check body temperature, pulse, breath sounds and voice during the onset period. A preliminary diagnosis is made clinically, but the pathogens cannot be diagnosed from clinical symptoms and signs. The pathogenic diagnosis is based on the relationship between the patient's disease background and the microorganisms, that is, the epidemiological basis.

8. Laboratory diagnosis: Get samples as soon as possible after admission: commonly used sputum specimens, blood, urine and lower respiratory secretions, etc., detection methods are:

(1) sputum: Take deep sputum for Gram staining. If there are pure bacteria, such as Gram-negative bacilli, it may be Haemophilus influenzae/Gram negative aerobic bacteria, such as Gram-positive bacteria. In the form of a double grape, it may be a real pathogen. At this time, convective immunoelectrophoresis of the corresponding suspected sputum is a sensitive and specific detection method.

(2) Blood specimens: Generally take early and late double blood samples, perform bacterial culture on early blood specimens, isolate and identify pathogenic bacteria, and determine the pathogens by serum agglutination test. For other pathogens such as mycoplasma, Chlamydia psittaci, virus and Legionella, etc. Enzyme-linked immunosorbent assay, fluorescein-labeled antibody assay can be used to detect the corresponding antibodies in serum. Any enzyme-linked immunosorbent assay (ELISA) IgM positive or IgM double serum can be diagnosed by pathogen diagnosis. The polymerase chain reaction (PCR method) established several years can directly and quickly detect the specific nucleic acid sequence of the pathogen, and make a diagnosis quickly and accurately.

(3) Urine specimen: commonly used latex agglutination test method to determine pathogenic antigens (such as Streptococcus pneumoniae antigen and Haemophilus influenzae type B antigen.

(4) Lower respiratory secretions: A better method for obtaining secretions is bronchoalveolar lavage (BAL), with a tethered catheter (TPC) method or percutaneous lung puncture and aspiration method. For pathogen isolation and culture, rapid PCR in vitro amplification can also be used to make pathogenic diagnosis in a short period of time.

Various methods have been established for the experimental diagnosis of socially acquired pneumonia caused by Legionella, which has been widely recognized by clinicians in recent years. However, each method is difficult to diagnose Legionella infection alone, so it is usually emphasized that it is used at the same time. The method is to diagnose the bacteria. The method commonly used in clinical practice in China is the direct fluorescein-labeled antibody method. This method requires a variety of antibodies against fluorescein to be completed in a short time. The DNA probe assay is specific and The sensitive method can complete the detection of specimens within a few hours. At present, the supply of commercial detection reagents is a better method for rapid detection of Legionella infection.

9. Pathogen diagnosis: The diagnosis of pathogens is of great significance for the treatment of pneumonia, disease judgment, prognosis judgment and future experience. Clinicians have been constantly seeking and exploring various methods to achieve The pathogen diagnosis of pneumonia, however, has not been solved ideally so far. The problems in the diagnosis and differential diagnosis of pneumonia pathogens are:

1 There are many kinds of pathogenic microorganisms that can cause pneumonia, and there is no absolute characteristic between different microorganisms or different types and subtypes of the same microorganism, whether it is clinical manifestation or X-ray image. Therefore, it is only from clinical manifestations and (or) The upper part of the X-ray image is difficult to make a positive diagnosis of pathogens.

2 About 30% of pneumonia patients do not produce sputum.

3 About 30% of pneumonia patients have been treated with antibiotics before or at the time of admission.

4 Among the various pathogens causing pneumonia, about 25% of pathogens have not been directly confirmed in clinical laboratories, such as viruses, Legionella, and Bernard's rickettsia.

5 Many immune serological test results still have a considerable proportion of false positives.

6 Even if a certain microorganism is isolated from the sputum, it is difficult to affirm the pathogenic microorganism when it is unable to exclude the upper respiratory tract pollution. Due to the above factors, the pathogen diagnosis rate in clinical practice has been very low, and foreign literature reports generally It is only 10% to 36%, and even in large comprehensive hospitals, the pathogen diagnosis rate of pneumonia has been very low. The work in this area has yet to be worked hard in the future. At present, clinicians can only rely on existing conditions. On the basis of fully grasping the patient's medical history, clinical manifestations and X-ray image characteristics, the relevant pathogen examination methods are selected in order to make pathogenic diagnosis as much as possible.

Examination of socially acquired pneumonia

Blood test

(1) Changes in blood picture: Most bacterial pneumonia has an obvious increase in the total number of peripheral white blood cells, an increase in the proportion of neutrophils, severe cases of nuclear left shift and poisoning particles, and a few bacterial pneumonia such as Escherichia coli, patina The total number of leukocytes caused by monocytogenes can be normal or slightly increased, but the proportion of neutrophils is generally increased. In patients with bacterial pneumonia, if the total number of white blood cells is reduced, it often indicates poor prognosis, viral pneumonia or other pathogens. The white blood cell count of pneumonia can be no significant change. The blood white blood cell count of patients with viral pneumonia can be lower than normal. If there is a bacterial infection, the number of white blood cells will increase. When judging the blood picture of pneumonia patients, the patient's bone marrow should be paid attention to. Hematopoietic reserve functional status, whether there is alcoholism and liver and kidney failure, etc., because the above factors may affect the change of white blood cell count in the inflammatory response.

(2) changes in bone marrow: general mild pneumonia bone marrow can be no significant changes, moderately above pneumonia patients with bone marrow can be responsive to inflammation, responsive to proliferative changes, severe symptoms of severe pneumonia or bone marrow patients with sepsis The image may be characterized by reduced hematopoietic function or significantly inhibited, but generally reversible, and returns to normal as the condition improves.

(3) blood gas analysis: general pneumonia due to excessive ventilation arterial blood gas analysis often showed mild hypocapnia and respiratory alkalosis, blood perfusion through the alveolar consolidation zone without ventilation, due to ventilation / blood flow ratio imbalance And physiological shunt can lead to hypoxemia, severe regional pneumonia or complicated with severe bronchospasm, respiratory failure and systemic sepsis patients can have severe hypoxemia, respiratory and / or metabolic acidosis.

(4) Pathogen examination: pathogens such as bacteria, fungi, mycoplasma, rickettsia, etc. can be used as pathogens for blood or bone marrow culture. The positive results have a positive effect on clear etiology diagnosis, guiding treatment and prognosis. Under normal circumstances, the positive rate is not high. Only in the case of a short period of bacteremia or concurrent sepsis in the early stage of the disease, the positive rate of blood culture will increase. For example, if the blood sample is taken after the early application of antibiotics, the positive rate is lower. Therefore, the positive rate should be lower. Blood samples were taken early for bacterial culture before antibiotic application.

(5) Examination of other hematological indicators: patients with general pneumonia may have mild to moderate erythrocyte sedimentation rate, mild elevation of transaminase or other enzymatic indicators, and blood cell sedimentation rate of patients with severe pneumonia or septicemia may reach 100 mm/h or more. The changes in the enzymatic indicators were more obvious, and even obvious changes in liver and kidney function indicators appeared.

2. Sputum examination

Microscopic examination of the secretions of the respiratory tract and pathogenic examination are very important for the rational treatment of pneumonia, but they are often insufficiently understood in actual clinical work. The main reason is that the reliability of the results of the sputum specimens is questioned, and the second is confrontation. The probability of detection of positive results of specimens lacks sufficient patience. In recent years, people have once again given enough knowledge about the importance of sputum examination in the diagnosis and treatment of pneumonia, and have made new explorations in theory, therapy and quality control. Strict quality control indicators improve the reliability of sputum specimens. The United States stipulates that less than one or two oral squamous epithelial cells in each high power field are qualified sputum specimens, and some use freshly taken from the diseased population under bedside surveillance. Sputum specimens are immediately prepared or inoculated on site to minimize contamination and maintain the quality of pathogens in the sputum. For some critically ill, chronically ill and refractory patients, and some special patients with chronic illness or immunosuppression, In order to obtain reliable sputum specimens.

In recent years, it has been advocated to use a protective sterile sputum brush to directly sample from the lesion through fiberoptic bronchoscopy. This adds some pain to the patient, but it is related to the reliability of pathogen diagnosis and the importance of guiding treatment and prognosis. Compared with, after all, it is the most economical, the most simple and effective method. Fresh sputum specimens should be subjected to Gram staining and pathogen culture. The wet cell microscopic examination of cell types can help to judge the reliability of specimens by mucus or purulent sputum. The specimen was coated on a glass slide and emulsified with a few drops of physiological saline, observed at 00 times. Polymorphonuclear leukocytes and alveolar macrophages were observed from the sputum specimens of the lower respiratory tract, and the wet sputum specimens were treated with the anti-capsular antibody mixed preparation to make the capsule swollen. Or stop the reaction, can improve the accuracy of analysis of pneumococci, if the patient is less likely to use distilled water or saline inhalation to stimulate cough, the diameter of the aerosolized particles should be between 0.8 ~ 10m, can stimulate most patients Cough, cough, there are reports of about 80% of AIDS patients with pneumonia and a small number of non-human immunodeficiency virus infection patients using this method Sputum, a detachable card Pneumocystis carinii.

3. Serological examination

Immune serological test is not a routine method in the diagnosis of pneumonia, but it still has certain value for the pathogenic diagnosis of pneumonia. Foreign reports can make a reference value for nearly one-fourth of patients with pneumonia. The more commonly used methods are convective immunoelectrophoresis detection of specific polysaccharides for the diagnosis of Streptococcus pneumoniae, muramic acid antibody assay for the diagnosis of staphylococci, condensate collection test for the diagnosis of Mycoplasma pneumoniae, and the external reaction to diagnose rickettsial pneumonia, The immunofluorescence technique for the diagnosis of Legionella, etc., the insufficiency of the immunological serological test method in the diagnosis of pneumonia pathogens is that the specificity and sensitivity are not ideal, and most of them take too long, and the guidance for early diagnosis and treatment is of little significance. However, the value of retrospective diagnosis is relatively large, generally requires high technology and equipment, and is difficult to popularize. Currently, the immunofluorescence method is the most successful for the diagnosis and application of Legionella, and its sensitivity can reach more than 75%. Between 95% and 99%, the results can be obtained within 24 to 48 hours. The reference value of the immune serological test for viruses is more limited. If there are many types of viruses, rapid transformation, higher technical requirements, and longer time, the practical value of clinical application is not large, mainly for retrospective diagnosis investigation. It is worth mentioning that in October 1994 At the 3rd Asia-Pacific International Virology Conference held in Beijing, the method of rapid diagnosis of viruses using monoclonal antibody technology developed by Chinese scholar Duan Pei-ru was able to accurately and simultaneously detect influenza virus and parainfluenza within 2 to 3 hours. A total of eight respiratory viruses, including viruses, adenoviruses, and respiratory syncytial viruses, are diagnosed at a rate 100 times faster than the classical virus isolation method, showing good prospects for the rapid diagnosis of clinical pathogens of viral pneumonia.

4. Polymerase chain reaction check pathogen

The immunological serology method is to confirm the presence of pathogens by detecting the antibody components of the pathogens in the specimen, and the polymerase chain reaction detection method is to directly detect the antigen components of the pathogens in the patient specimen, and the polymerase chain reaction (PCR) is An in vitro DNA amplification technology based on the principle of DNA replication, that is, the pathogen DNA fragments in the specimen to be tested are subjected to high temperature denaturation (90-95 ° C) - low temperature annealing (37 ~ 70 ° C) - moderate temperature extension (70 ~ 75) After the procedure of °C) is repeated for 25 to 35 cycles, the copy number of the original DNA fragment can theoretically be increased by more than 106 times to detect a very small amount of pathogen DNA in the specimen. The technique has four remarkable features:

(1) High sensitivity: This is the most prominent feature of PCR. The literature reports that 1 to 100 fg of DNA in the specimen can be detected, which is equivalent to 1 to 20 bacteria. In the exclusion of various interference factors in clinical specimens, the sensitivity of actual clinical detection is about The amount of DNA around 1000 bacteria.

(2) Strong specificity: The specificity of PCR depends mainly on whether the selected amplified fragment is a specific nucleic acid fragment of the cell (or pathogen). In addition, a higher annealing temperature is selected to correctly bind the primer to the template. It also increases the specificity of PCR.

(3) Convenience: In addition to the complicated and high requirements for nucleic acid preparation of certain bacteria and clinical specimens, the operation of PCR is relatively simple, especially the application of heat-resistant DNA polymerase and the advent of DNA thermal cycler, enabling PCR operation. Automate, save time and effort.

(4) Rapid: PCR detection of clinical specimens, amplification from nucleic acid CR, electrophoresis detection to photography takes only 1-2 days.

PCR technology was first established in 1983 by Mullis, etc., and applied to the clinic in the late 1980s. It was introduced into China in the early 1990s. At present, this technology has not been widely implemented in China, and it has been successfully applied to clinically used tuberculosis and mycobacterial PCR detection technology. Mycoplasma PCR detection technology is being used in clinical practice.

5. Chest X-ray examination

There are two main purposes in the diagnosis of pneumonia: one is to confirm the presence or absence of pneumonia, and the other is to identify the lesion site. The high-quality X-ray posterior chest radiograph helps to show the lesion in the posterior region of the left heart, even Thus, all patients with pneumonia should take a lateral chest X-ray to help locate the lesion. The X-ray manifestations of pneumonia depend on the lesion (alveolar or interstitial lung), and the extent of the lesion (alveolar, lobular, lung or large lobe) ), the nature of the lesion (suppurative, non-suppurative), and the path of infection (such as blood or airborne), but also closely related to the cause and pathogen species, therefore, by analyzing the lesion location, extent, morphology and Distribution characteristics, etc., sometimes help to speculate the cause and pathogen types. The dynamic change of pneumonia shadow is important for the differential diagnosis of pneumonia and other shadows. Pneumonia can be expressed on X-ray, according to its performance characteristics, combined with pathology. The basics are as follows:

(1) Enhanced lung texture: This sign is common in bronchial pneumonia. The lung texture enhancement caused by viral infection is often more obvious than bacterial infection. This is the X-ray manifestation of pathogen transbronchial infection and bronchial spread. From the trachea to the terminal bronchioles and even the respiratory bronchus, mucosal exudation, proliferative or necrotic inflammation is seen. The bronchial lesions below 5 or 6 are heavier, and the terminal bronchioles and acinus belong to the lobule. Respiratory bronchioles are heavier, often accompanied by peribronchiolarulitis, so some people think that lung texture enhancement is an early X-ray manifestation of pneumonia. Pulmonary texture enhancement caused by pneumonia is mostly common, and the texture edge is fuzzy. Vascular texture enhancement phase identification.

(2) nodule shadow: this sign is more common in adenoviral pneumonia, respiratory syncytial virus pneumonia and measles virus pneumonia, etc., can also be seen in bacterial pneumonia and fungal pneumonia, the lesion diameter is mostly 1 ~ 6mm, edge comparison Blurring, more common in the middle and lower lung fields, pathologically for terminal bronchioles or respiratory bronchioles, or acinar-like alveolitis, the former with the common lung texture and emphysema coexist, More common in viral infections, the latter mostly coexist with small leaf fusion lesions, can be seen in viral infections or bacterial infections.

(3) small patchy or patchy fusion shadow: this disease can be seen in various causes of bronchial pneumonia, on the X line as a diameter of 1 ~ 2.5cm edge blurred patchy shadow, patchy shadow In the pathologically, the patchy shadow is exudative or necrotizing alveolitis in the lobules, and the interlobular septa of the lesion is clear, even after several lesions are fused. In terms of distribution, this type of lesion is more Distributed in the lungs on both sides, generally the lower leaves are more than the upper leaves, more inside than outside, more than before.

(4) Lung segment and large leaf shadow: This performance is more common in pneumococcal pneumonia, pneumonia bacillus pneumonia, Staphylococcus aureus pneumonia, K. pneumoniae pneumonia and adenovirus pneumonia, pneumococcal pneumonia and pneumonia bacillus pneumonia occupy a lung Segments or a lobes are mostly, while Pneumocystis carinii, adenovirus pneumonia can involve several segments of the lungs or lungs at the same time. The bronchial images can be seen in the dense shadows, and the lesions are clearly defined in the pathological gross specimens. In the brownish-red or gray-white consolidation zone, the lesion volume does not shrink. Microscopically, fibers are seen in the alveolar space, and red blood cells and white blood cells are exuded.

(5) Strip-like and reticular shadow: This disease is found in radiation pneumonitis, chronic pneumonia and interstitial pneumonia. The lesions are mainly hyperplasia, mostly occurring in the alveolar wall, the middle lobe interval, and may also be mixed with substantial alveolitis. This hyperplastic lesion can also coexist with part of the lung collapse. Chronic pneumonia can be accompanied by bronchiectasis. It appears as a patchy irregular strip-like mixed shadow on the X-ray. The edge can be clear or blurred. This lesion is slower to absorb than exudative alveolitis.

(6) Spherical shadow: This disease is seen in Staphylococcus aureus pneumonia, fungal pneumonia, etc. The former is abscess in pathology, the boundary is blurred or relatively clear, blood-borne Staphylococcus aureus pneumonia is often multiple, on the X line, gold and Portuguese Pneumonia can be expressed as multiple or single spherical shadows, with a diameter of about 1 to 3 cm. The edges are clear. The density is relatively uniform, but a cavity can be formed in a short time. The pathological basis of spherical shadow formed by fungal pneumonia is Abscess or granuloma.

(7) Cavity: mainly seen in suppurative pneumonia and fungal pneumonia, especially Staphylococcus aureus pneumonia, showing a ring-shaped transparent area on the X-ray, the edge is clear or fuzzy, the wall thickness is different, the lesion and normal lung The tissue boundary is unclear, and the cavity is necrotic tissue. If the drainage bronchus forms a flap due to inflammation, the air volume increases due to the increase of air volume in the cavity, thus increasing the cavity and thinning the wall. Generally speaking, the disease is a lung balloon. This phenomenon is found in Staphylococcus aureus, Gram-positive cocci infections such as type A hemolytic streptococcus, and it appears as a thin-walled cavity on the X-ray. It can disappear in a short time after the pneumonia is taken, and it can remain for several months.

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Diagnostic criteria

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Differential diagnosis

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