Anaerobic pneumonia in the elderly
Introduction
Introduction to anaerobic pneumonia in the elderly Anaerobic pulmonary infection is caused by anaerobic bacteria, inflammation of the trachea, bronchus, lung parenchyma and pleural cavity. There are many kinds of anaerobic bacteria, and the pathogenicity is not the same. It is one of the common pathogens causing lung infection. basic knowledge The proportion of the disease: the incidence of chronic bronchitis in the elderly is about 8% Susceptible people: the elderly Mode of infection: respiratory transmission Complications: shock, sepsis, arrhythmia, respiratory failure, heart failure
Cause
The cause of anaerobic pneumonia in the elderly
Causes:
Anaerobic anaerobic bacteria:
Such anaerobic bacteria grow best under anaerobic conditions and poorly under aerobic conditions, and Clostridium difficile and Clostridium difficile are such.
Common anaerobic bacteria in which lung infections are:
(1) Gram-negative anaerobic bacillus: a common anaerobic bacterial infection in the lungs, reported in the literature on aspiration pneumonia, necrotizing pneumonia, lung abscess and empyema, isolated from Gram-negative anaerobic bacteria accounted for approximately 53.67 %, 56.45%, 50.87% and 39.29%, of which Bacteroides accounted for the first place, followed by Fusobacterium.
1 Bacteroides: Gram-negative Bacillus-free, a few strains with capsule or flagella, obligate anaerobic, can utilize intermediate metabolites of sugar and protein, model bacteria are Bacteroides fragilis, and the morphology of the cells is short rod The dyeing is uneven, the middle dyeing is light or not colored, so that the cells are vacuolized, the ends are round and densely stained, irregular on the solid medium, the performance varies, and the culture conditions are slightly changed, such as anaerobic Insufficient conditions, malnutrition or accumulation of acidic products, the appearance of multi-form bacteria, Bacteroides causing lung infections are most common in Bacteroides fragilis and Bacteroide producing bacillus.
2 Clostridium: may be Gram-negative Bacillus-free, obligate anaerobic, no flagella, can use sugar and peptone, the model strain is Fusobacterium nucleatum, the bacteria is enlarged in the middle, the ends are sharp, and there are gram in the bacteria. Positive granules vary in length and shape, and the morphology is relatively regular. The cells are double, and the tip is at the tip. The Fusobacterium belonging to the genus Fusobacterium is more common in the lung infection.
(2) Gram-positive anaerobic cocci: Gram-positive anaerobic bacteria is second only to Gram-negative anaerobic bacteria in lung infection, and the literature reports that it accounts for about 1/4 to 1/3 of the above-mentioned lung infections. Among them, Digestive Streptococcus and Digestococcus are common.
1 Digestive Streptococcus: Digestive Streptococcus is small, 0.5 ~ 0.6m in diameter, arranged in pairs or in chains, forming a round, smooth, convex, gray-white, opaque, non-hemolytic colony with a needle tip diameter of 1mm. The most common Gram-positive anaerobic cocci for lung infection.
2 Digestive genus: The bacteria of the digestive bacterium are round, 0.3-1.3m in diameter, arranged in double, short-chain or piled, growing slowly, and forming small colonies in 2 to 4 days, which is more common in lung anaerobic infection. Bacteria.
(3) Gram-negative anaerobic cocci: Veerococcus eutropha in Gram-negative anaerobic cocci, which is also the pathogen of lung anaerobic infection, accounting for 3.7% of lung anaerobic infections. Small, 0.3 to 0.6 m in diameter, sometimes into a short chain, positive for Gram in the early stage of culture, and negative for Gram overnight.
(4) Gram-positive anaerobic bacteria: Gram-positive anaerobic bacteria account for about one-fifth of anaerobic bacteria in the lung, of which the genus Eubacterium, Propionibacterium and Clostridium are the most common.
1 genus Bacillus: The genus Bacillus is Gram-positive without Bacillus, the morphology is regular, the size of the cell is (0.6 ~ 1) m × (2 ~ 4) m, often arranged in single, double, short chain, Gram stain The positive colonies are small round and flat, translucent, gray, and not hemolyzed. The model bacteria are visceral bacilli, accounting for about 1/4 of the infection of Gram-positive bacilli in the lungs.
2 Propionibacterium: Gram-positive non-spore polymorphic bacterium, straight or slightly curved, rod-shaped, size (0.5 ~ 0.8) m × (1 ~ 5) m, uneven staining, arranged in X, Y , V and grid, no capsule, no flagella. Colony is small, round, gray or other colors, opaque, model bacteria for Propionibacterium fuligis, is also a common bacterial infection of the lung.
3 Clostridium: The middle part of the cell is swollen in shape, and the model is Clostridium butyricum. The shape of the cell is straight or slightly curved, the length or the width is constant, and the ends are pointed or round, arranged in a single, double, short chain or diverse. .
Old age is an important factor in the onset. It is often caused by poor oral hygiene, periodontitis, craniocerebral injury, cerebrovascular disease, epilepsy, alcoholism, general anesthesia, etc. In addition, bronchoconstriction, bronchonews, obstructive pneumonia, bronchiectasis Basic diseases such as pulmonary embolism are also likely to cause anaerobic infection.
Moderate anaerobic bacteria:
These anaerobic bacteria can grow in 2% to 8% oxygen concentration, and can be separated by exposure to air for 60 to 90 minutes, causing common anaerobic bacteria such as Bacteroides fragilis, Clostridium perfringens These are all such types and are the most common type of anaerobic bacteria in the clinic.
Extreme anaerobic bacteria:
These anaerobic bacteria are extremely sensitive to oxygen and die at 0.5% oxygen concentration or less than 10 minutes in air. Because they are extremely difficult to isolate in clinical laboratories, they are still unknown.
Pathogenesis:
The entry of anaerobic bacteria into the lungs does not necessarily lead to infectious lesions. The anaerobic infection of the lungs is also the result of mutual comparison between microorganisms and the body. The defense ability of the body is the main factor determining whether infection can occur, and anaerobic bacteria. The pathogenic process plays an important role in causing infection.
1. The body's defense ability is reduced:
(1) Decreased systemic immune function: In some terminal stages of chronic diseases, such as diabetes, cirrhosis, and kidney disease, in addition to causing common bacterial infections, it is easy to cause anaerobic infection, and tumor patients receive radiotherapy and chemotherapy. Patients with organ transplantation and connective tissue disease use anti-metabolite drugs. Patients with hematological diseases receive steroid therapy. Chronic alcoholism can cause severe immune function decline and easily lead to anaerobic infection.
(2) Local defense ability disorder: including barrier function of local mucosa, reduction of redox potential of local tissue and impaired vitality of phagocytic cells and sterilization system, local mucosal barrier function is more common in such as bronchiectasis, bronchogenic carcinoma, Chronic obstructive pulmonary disease and other lung diseases, its damage is not only conducive to anaerobic bacteria invasion, but also conducive to bacterial reproduction and spread, tissue redox potential is often reduced by local tissue vascular disease, shock, edema, trauma, surgery, cancer And aerobic bacteria growth, etc., under normal circumstances, although anaerobic bacteria can enter the lower respiratory tract, but because the respiratory mucosal tissue blood supply is normal, maintaining a redox potential of 150mV, is not conducive to its growth, but due to the above reasons for oxidation When the reduction potential drops below 150mV, the anaerobic bacteria can enter the tissue growth and reproduction. The phagocytic cells and the bactericidal system are often reduced in the presence of hypoxia, ischemia, acidosis and bacterial metabolites, and are also beneficial to anaerobic bacteria. Growth and reproduction.
2. The pathogenic role of bacteria:
(1) Adhesion and adhesion: It is the first step of the anaerobic infection process. Anaerobic bacteria of different genus species are attached to the surface of target cells by different mechanisms due to some special structures of their own, such as the main utilization of Bacteroides fragilis. Pili and spores are attached to mucosal epithelial cells. The phytohemagglutinin-mediated mechanism is attached to galactose-containing target cell receptors via arginine, and proteolytic enzymes and other immunoglobulins are hydrolyzed by proteases. Complement reduces the blockage of bacterial surface receptors by immunoglobulins and complement components.
(2) Invasive tissue: If the mucosal epithelial structure is intact, most anaerobic bacteria cannot directly invade the tissue except for necrosis, but in the case of impaired mucosal integrity, the anaerobic bacteria attached to the target cells rely on themselves. The resulting protease, phospholipase C, dissolves mucosal epithelial cells into the tissue.
(3) Growth and reproduction: After the bacteria enter the tissue, whether the local infection can be formed depends on local metabolism, bacterial nutrition and bacteria's defense ability against the host. If the tissue is decomposed due to ischemia and hypoxia, carbohydrate degradation and protease activation are caused. The release of amino acids increases the local pH and redox potential of the tissue on the one hand, and provides abundant nutrients for the anaerobic bacteria on the other hand, promoting its local growth and reproduction. In addition, the bacteria entering the tissue can also produce many substances resisting. Host defense mechanisms, such as Bacteroides fragilis, which protect themselves from phagocytosis by phagocytic cells, can also produce soluble substances such as succinic acid and other short-chain fatty acids that inhibit the chemotaxis of polymorphonuclear leukocytes and macrophages to bacteria. Phagocytosis and killing, many anaerobic bacteria can also produce some substances to inhibit and destroy the host's humoral immunity. For example, Bacteroides fragilis lipopolysaccharide can attenuate the conditioning of complement, proteolytic enzymes produced by Bacteroides melanogaster degrading complement and immunoglobulin Wait.
(4) Tissue damage: Anaerobic bacteria produce toxins, enzymes and soluble substances in the process of infection. In addition to functioning at various stages, they can directly damage the structure of tissues and cells, such as Clostridium perfringens. The toxin type A can dissolve red blood cells and tissue cells, causing hemolysis and tissue necrosis. The heparinase produced by Bacteroides decomposes heparin, promotes blood coagulation, and may cause thrombophlebitis. The production of collagenase by Bacteroides melanogaster destroys connective tissue. Bacteroides producing hyaluronidase, neuraminidase, DNase, etc. are all related to the spread of disease and infection.
Pathological changes:
Inhalation of the infected site, the most common is the posterior segment of the right upper lobe, followed by the lower back of the lower lobe, often single, less involved in the posterior segment of the left upper lobe, may be related to the anatomy and position of the bronchi, The blood-borne dissemination is multiple, no distribution, more common in the lower edge of the lungs, early small lesions, and then gradually merge, the direct spread is often the first to involve the lung closest to the primary lesion Or the pleura, such as the underarm abscess, the first to cause empyema.
The histological changes of anaerobic pulmonary infection are similar to those of other bacteria. In the initial stage, if caused by inhalation, early bronchiole obstruction, alveolar edema and inflammatory cell infiltration, bronchial pneumonia, Blood line disseminators, bacterial embolism embolization of pulmonary arterioles, resulting in perivascular infiltration and small infarcts of nodular lung tissue, followed by a large number of inflammatory cell infiltration, bacterial thrombus to local tissue ischemia, promote anaerobic infection, aggravate tissue necrosis , necrotizing pneumonia and lung abscess, necrotizing pneumonia, mainly manifested as large leaf consolidation and tissue necrosis, which can form multiple small cavities less than 2cm, necrotic areas with neutrophil infiltration, large necrotic tissue shedding Lung gangrene, if the liquefied pus accumulates in the abscess, causing the pressure to increase, and finally rupture into the bronchi, coughing up a large amount of purulent, if the air enters the abscess, the liquid level appears in the abscess, and the cavity is larger when the lung abscess occurs. Often single, if extended to the surrounding tissue, forming a number of abscesses, if close to the pleura, localized fibrinous pleurisy can occur, causing pleural adhesions, Lung abscess edge tension, to rupture when the pleural cavity, pneumothorax can be formed pus, bronchial if poor drainage, necrotic tissue remaining in the abscess, inflammation persists, become chronic lung abscess.
Prevention
Anaerobic pneumonia prevention in the elderly
1. Three levels of prevention:
(1) Primary prevention: The elderly are more susceptible to pneumonia due to aging and degeneration of the lungs and changes in local anatomy. Among them, anaerobic pneumonia is often inhaled and is endogenous, so it is for the elderly. Should strengthen nursing, 1 suffering from stroke, brain atrophy of the elderly, long-term bedridden patients, their lives can not take care of themselves, swallowing difficulties, drinking water ruminant, which requires the nursing staff to be particularly careful when eating, the bed is raised appropriately Some, when the macroscopic aspiration is found, the body should be quickly drained or attracted to remove the contents of the airway. If necessary, use fiberoptic bronchoscope to remove the food residue from the airway, so as not to block the bronchus and cause anaerobic pneumonia; When sudden changes, should pay attention to keep warm, prevent colds, reduce the chance of pneumonia; 3 elderly people try to drink less to reduce the chance of aspiration; 4 active treatment of tonsillitis, acute abdomen such as appendicitis perforation and other purulent infections, to reduce lungs The occurrence of anaerobic infections.
(2) secondary prevention: the onset of pneumonia in the elderly is insidious, and it is not easy to be found. If the patient's health deteriorates, the appetite declines, anorexia, burnout, urinary incontinence, acute confusion, mental dysfunction or sudden deterioration of the underlying disease, the condition recovers slowly. All should pay attention to the atypical change of pneumonia, should seek medical attention immediately, check the body in detail, do "X" line examination, check the bacteria, check the pneumonia as soon as possible, and timely medication.
(3) Tertiary prevention: anaerobic pneumonia is a non-single bacterial infection, mostly mixed infection, using effective antibiotics for anaerobic bacteria, according to the results of drug susceptibility test, combined with other antibiotics, after the condition improves, no When the fever, cough, cough, and sputum disappeared, the X-ray results were observed and should be discontinued after the X-ray shadow was basically dissipated to reduce the possibility of evolution into chronic pneumonia, resulting in impaired lung function.
2. Risk factors and preventive measures: The risk factors for anaerobic pneumonia in the elderly are: smoking can reduce airway defense function and increase the chance of suffering from pneumonia; poor oral hygiene, difficulty swallowing, coughing, prolonged bed rest, coma is Common causes of aspiration pneumonia; throat surgery and anesthesia are common causes of iatrogenic anaerobic pneumonia; acute tonsillitis, suppurative appendicitis can spread to the lungs, forming an anaerobic infection.
The interventions are as follows: maintain oral hygiene, strengthen oral care, timely treatment of dental caries, gingivitis, tonsillitis, patients with long-term bed rest, difficulty swallowing, cough should be observed to prevent gastric juice from flowing back to the trachea, should be careful when eating. Set your posture, eat slowly, add more liquid food, if necessary, use a nasal feeding diet.
Complication
Elderly anaerobic pneumonia complications Complications shock sepsis arrhythmia respiratory failure heart failure
Complications are common, and most of them are related to a variety of underlying diseases. Common are: shock, sepsis, sepsis, arrhythmia, water and electrolyte disorders, acid-base imbalance, respiratory failure, heart failure, multiple organ dysfunction, etc. After the complications appear, the condition is heavy, rapid progress, mortality high.
Symptom
Symptoms of anaerobic pneumonia in the elderly Common symptoms High fever Chronic cough, shortness of breath, dyspnea, nausea, nausea, weight loss, body discomfort, abdominal pain, weakened breath sounds
The clinical manifestations vary widely, and a few are acute courses, most of which are insidious onset.
Typical performance
1 aspiration pneumonia: have a history of primary disease and aspiration, rapid onset, sudden chills and high fever, body temperature of 39 ° C or more, with cough, cough mucus or mucus purulent, cough sputum is anaerobic infection Characteristics, but the literature reports that the disease cough sputum only accounts for 37.8%, therefore, the sputum is not odor can not rule out the possibility of anaerobic infection, inflammation involving the pleura can cause chest pain, with the expansion of the lesion range, progressive dyspnea Severe symptoms of poisoning may be accompanied by nausea, vomiting, bloating and diarrhea. Signs: The lesions are smaller, there may be no abnormal signs, the lesions are large, there may be bun, nasal fan and dyspnea, lung auscultation is voiced or real, auscultation of breath sounds is reduced, sometimes can be heard and voice,
2 necrotizing pneumonia: This disease is characterized by the formation of many abscesses and necrosis with a diameter of less than 2cm. The severe spread rapidly causes large necrosis and shedding of the lung parenchyma, and even forms a lung abscess. About 75% of patients have a history of aspiration, and the patient's condition is better. Heavy, body temperature up to 40 ° C, cough severe, cough volume, 61% of patients cough sputum, lung abscess, cough up a lot of pus sputum, up to hundreds of milliliters per day, patients have shortness of breath, cyanosis, lung examination majority The auscultation is voiced, the breath sound is weakened, and the mortality rate is high. Patients with chronic lung abscess have chronic cough, cough and sputum, repeated hemoptysis, often showing anemia, weight loss and other chronic consumption states. The physical examination shows that the affected side chest collapses slightly, and the percussion is dull. The respiratory sound is reduced, and the blood-borne disseminated lung abscess has symptoms of systemic sepsis caused by chills and hyperthermia caused by the primary lesion. After several days to 2 weeks, pulmonary symptoms such as cough and cough appear. Usually there are not many sputum, very little hemoptysis, most of the signs are negative,
3 empyema: slow onset, often after 1 week to weeks after the onset of symptoms, the heat is higher, up to 40 ° C, the heat period is longer, half of the cases of weight loss significantly, such as lung abscess secondary, cough is obvious, Cough a large amount of purulent sputum, such as subarachnoid abscess directly spread, dry cough, chest pain is obvious, the secretion of empyema is purulent, foul odor, sticky, forming many small abscesses, more difficult to suck out.
2. Atypical performance
Insidious onset, many symptoms are not typical, often no fever, cough, cough, chest pain symptoms, more common symptoms are: increased respiratory rate, shortness of breath and general discomfort, weight loss, loss of appetite, burnout, acute confusion, spirit Symptoms such as wilting and systemic poisoning may also cause sudden deterioration of the underlying disease, or slow recovery of the disease. For example, heart failure recurs or worsens during treatment. A small number of patients have prominent gastrointestinal symptoms, often showing nausea, vomiting, abdominal pain, Diarrhea, anorexia, indigestion, etc., accompanied by respiratory symptoms, signs: typical physical signs are less, half of the patients can not hear the voice in the lungs, 1/4 of the patients have no abnormal auscultation in the lungs, even if they hear the voice, Easy to be confused with chronic inflammation and heart failure.
Older people with lung infections caused by anaerobic bacteria have the following characteristics:
1 mostly have primary diseases and predisposing factors; 2 the course can be acute or chronic; 3 sputum and pleural effusion have a foul odor; 4 infected lesions with necrotic tendency; 5 insidious disease, atypical symptoms; 6 specimens Direct smear showed a large number of bacteria and normal bacteria culture was negative; 7 more complications, high mortality.
Examine
Examination of anaerobic pneumonia in the elderly
Blood around
The blood white blood cell count and neutrophils increased significantly, the total number can reach (20 ~ 30) × 109 / L; neutrophils in 80% ~ 90%, the chronic onset, the total number of white blood cells can be no significant changes, but There are varying degrees of anemia.
2. Fiberoptic bronchoscopy
Fiberoptic bronchoscopy with double-sleeve sampling for bacterial culture can also attract antibiotics into the pus and lesions, promote bronchial drainage and healing of the abscess, and help to detect the underlying lesions.
3. Bacteriological examination
(1) Anaerobic culture: As the most reliable diagnostic basis, since the coughed sputum is contaminated by anaerobic bacteria that are normally colonized by the oropharynx, special attention should be paid to the collection of specimens. The following methods are often used:
1 Circumcision puncture: This measure is a measure taken to reduce oropharyngeal contamination. It is valuable when detecting anaerobic infections in the lungs, but it is not suitable for patients with ongoing tracheal intubation.
2 spleen lung puncture: the literature reported that the detection rate of the bacteria reached 84%.
3 fiber bronchoscope double casing method: the method uses a double-layer PTFE casing and a polyethylene ethanol plug in front of the casing to prevent contamination of the brush, and the brush is inserted into the fiber bronchoscope under direct vision. In the tracheal segment of the lesion, the specimen was brushed for culture, and the sensitivity of the method was reported to be 70%.
Avoiding oxygen exposure is another important problem in anaerobic culture. At present, the following methods are used to transfer specimens.
1Syringe transfer method: This method directly uses the syringe of the sample to transfer various liquid specimens, especially suitable for the specimens of the ring nail membrane puncture and the spleen lung puncture. The method is to extract the specimen with a sterile syringe. With the needle facing up, the excess air is expelled, the needle is inserted into the rubber stopper, the air is isolated, and sent to the laboratory.
2 anaerobic vial transfer method: suitable for all specimens in the syringe transfer method, using a sterile penicillin vial as a sampling bottle, sealed with an aluminum cap, the air in the bottle is removed, filled with nitrogen, continuously pumped 3 times, and finally filled with CO2, autoclave standby, when transporting, the specimen can be injected into the bottle with a sterile syringe.
3 large amount of liquid specimen transfer method: mainly used for the transfer of empyema pus, fill the specimen with the liquid specimen, then the air in the bottle can be removed.
The commonly used anaerobic culture medium is sodium thioglycolate solution, minced meat broth, and bovine heart and brain leaching solution preparation, which can be made into a solid or liquid medium on which anaerobic bacteria and facultative anaerobic bacteria are It can grow. If kanamycin is added at 100 g/ml, most facultative anaerobic bacteria are inhibited, and the bacteria that can grow are obligate anaerobic bacteria.
After anaerobic culture, the colonies were picked for smear microscopy and further biochemical identification, the so-called anaerobic three-level identification method, the reasons for anaerobic culture failure were:
1 specimen collection, transfer is not appropriate; 2 specimens are not immediately vaccinated; 3 culture time is too short; 4 specimens are contaminated by normal flora; 5 medium redox potential is too high; 6 anaerobic conditions are not enough, there is air during cultivation Enter;; 7 medium composition or pH is not suitable; 8 carbon dioxide concentration is not appropriate.
(2) Rapid diagnosis - gas chromatography detection: One of the characteristics of anaerobic bacteria is the production of a variety of volatile or non-volatile short-chain fatty acids and alcohols in their metabolism, while anaerobic bacteria The type of acid and the amount of alcohol produced may vary, so anaerobic bacteria can be identified by gas chromatography.
1 Gas Chromatographic Analysis of Early Cultures: Specimens were inoculated in anaerobic liquid medium, and cultured at 35 ° C for 12 h, the supernatant of the early culture of bacteria was taken, and then extracted and analyzed by gas chromatography. From the research, it was found that early culture The detection of propionic acid, isovaleric acid, valeric acid and succinic acid was related to the separation of anaerobic bacteria in the future. Among them, the correlation between the detection of butyric acid and isovaleric acid and anaerobic bacteria was the most relevant. Well, the two have diagnostic value for anaerobic bacteria: 0.2 mmol/L for butyric acid and 0.1 mmol/L for isovaleric acid. There is a significant correlation between the detection of isovaleric acid and the separation of Bacteroides fragilis. The detection of butyric acid - the isolation of Fusarium oxysporum and Fusobacterium is also significantly correlated.
2 Direct gas chromatography analysis: the pus, puncture fluid replaces the dry culture in the upper method for gas phase analysis, the biggest feature is that within 1h after receiving the specimen, it can be determined whether it is anaerobic infection, early clinical Provide a reference for treatment.
(3) Immunofluorescence method: directly discard the clinical specimens, and take the surface sediments evenly on the glass slides for fluorescent antibody staining. The above ++ is fluorescent staining positive, which is divided into direct immunofluorescence method and indirect immunofluorescence. law.
1 Direct immunofluorescence method: 140 samples of 16 different infection types were directly stained with this antibody and compared with bacterial culture. The results were consistent. The sensitivity of the diagnosis of Bacteroides fragilis was 100%. The specificity was 94.5%, the positive predictive rate was 83.5%, and the negative predictive rate was 100%.
2 Indirect immunofluorescence method: This method is used to compare Bacteroides fragilis in the clinical specimens, producing Bacteroides melanogaster and nucleic acid bacteria, and compared with the bacterial culture method, the coincidence rate of the two is 88.5%, 89.84% and 96%, respectively. However, the sensitivity was only 44.4%, 76.09%, 68.75%, and the specificity was 89.59%, 91.77% and 91.20%.
(4) Immunohistochemical grouping method: This method was applied to Capsella aeruginosa, 8 other Clostridium, 8 facultative anaerobic bacteria and aerobic bacteria, and repeated examination 10 times, except for Clostridium perfringens The rest of the bacteria are negative. Dilute the specimen to 2,500 bacteria per ml and cough up a large amount of pus sputum. It can be detected up to hundreds of milliliters per day. A stable positive result can be obtained with 5000 bacteria per ml. The method is strong in specificity, high in sensitivity, simple and rapid in method, and the result can be obtained in 2 to 3 hours, which is valuable for early diagnosis.
(5) Nucleic acid probe: It has the advantages of high specificity and sensitivity, and is not affected by sample placement and exposure to oxygen. It is suitable for anaerobic bacteria detection with strong pathogenicity, difficult cultivation and slow growth, due to extraction from specimens. The process of DNA samples is complicated, time-consuming, radioactive, short-lived, and not sensitive enough. It has not been widely used in clinical practice. In recent years, non-nuclear nucleic acid probe technology has been developed that has no radioactive hazard, long shelf life and simple detection procedures, such as Biotin nucleic acid probes, immunoribonucleic acid probes and chemical method probes, and the like.
(6) Polymerase chain reaction (PCR): using a specific sequence on a DNA strand of an anaerobic bacteria as a template, using a primer to synthesize a complementary sequence, and after several tens of cycles, the number of DNA is amplified to a million times. The sensitivity of the detection is improved. At present, the anaerobic bacteria detected by PCR in foreign countries include Clostridium difficile, Clostridium propioni and Clostridium.
Image performance
1. Aspiration pneumonia, the lesions are mostly located in the posterior or posterior lobe of the right lobe, showing a large dense and inflammatory shadow uniformly distributed along the lung segment, with unclear edges, multiple single-segment segments, and multiple shrapnel. The shadow is usually located in the peripheral part of the lung, close to the pleura, similar to general pneumonia. After 1 to 2 weeks, the tissue is necrotic, forming an abscess and developing necrotizing pneumonia.
2. Necrotic pneumonia is mainly characterized by the rapid formation of cavities in the solid shadows of dense lung segments, and lesions <2 cm in diameter not only invade one lobe.
3. Acute lung abscess shows a circular translucent area in a large thick shadow. The cavity is round and the inner wall is smooth. The liquid level is seen inside. The treatment is proper. The solid shadow and cavity are gradually reduced, disappearing or residual. Shadow.
4. Chronic lung abscess has a large difference in X-rays. The wall of the abscess is thick, the inner wall is irregular, and the size of the cavity is different. It may be accompanied by a liquid level, with fiber-optic lines around it, and different degrees of contraction of the lungs. Half of the secondary bronchus dilatation.
5. The cause of hematogenous dissemination is a small spherical inflammatory shadow or a neatly spherical lesion in the edge of the lung or both lungs, in which the abscess and the fluid level are visible.
6. The performance of empyema varies according to the amount of pus, and there is a large thick shadow on the affected side of the chest. If there is a purulent chest, the liquid level is visible.
Diagnosis
Diagnosis and identification of anaerobic pneumonia in the elderly
Diagnostic criteria
The diagnosis of anaerobic infection is mainly based on bacteriological examination. Before the lack of anaerobic culture and other examination conditions or examination, pulmonary infection occurs in the following cases or with the following conditions, often suggesting anaerobic infection or anaerobic Bacterial infection.
1 has a history of aspiration;
2 long-term application of aerobic bacteria antibiotics (such as aminoguanidine), but the effect is not significant;
3 infections that occur on the basis of tissue necrosis such as lung cancer, bronchiectasis, mild pulmonary infarction, and open chest trauma;
4 with or secondary to oral, abdominal and gynecological infections;
5 septicemia or multiple migratory abscesses;
6 lung abscess cavity or visible in the chest cavity;
7 sputum or pus has a rotten stench or black color, showing red fluorescence under ultraviolet light.
The following points may be bacterial clues to anaerobic infections:
1 routine culture of negative sterile pus and puncture, smear Gram staining a large number of bacteria with consistent morphology;
2 The culture produces gas and has a stench of corruption;
3 anaerobic colony growth in sodium thioglycolate liquid or agar deep;
4 can grow in a medium containing 100 g / ml kanamycin or neomycin;
5 The young colonies producing Bacteroides melanogaster can be red-fluorescent by ultraviolet light irradiation, and the clinical manifestations of anaerobic pulmonary infection have no distinguishing significance.
Differential diagnosis
Pneumonia caused by anaerobic bacteria, lung abscess and empyema should be differentiated from those caused by other bacteria.
