Anaerobic infection

Introduction to anaerobic infection Anaerobic bacteria are a major component of the normal flora and can cause infections in any tissue and organ in the body. In recent years, with the continuous improvement of culture technology, anaerobic bacteria have been isolated and identified in time, and reports of anaerobicinfection have gradually increased. The importance of anaerobic bacteria in bacterial infectious diseases has been increasingly recognized by clinicians. Value. Anaerobic bacteria are the main normal flora in the human body. The genus Bacteroides is the most in the oral cavity, the intestines, the urinary tract and the female genital tract. The Fusarium is mainly found in the upper respiratory tract and the oral cavity; the digestive cocci and the digestive streptococci are present in the intestine. , mouth, vagina and skin; Propionibacterium is often found in the skin, upper respiratory tract and vagina; Wyoming is present in the mouth, upper respiratory tract, vagina and intestines. Since anaerobic bacteria are normal flora in the human body, most anaerobic infections are endogenous. These bacteria are conditional pathogens that must be invaded and infected when systemic or local resistance is reduced. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: pneumonia phlebitis sepsis shock

Causes of anaerobic infection

Bacterial infection (75%)

Gram-negative bacteria

1. Bacteria: (1) Bacteroides: such as B. fragilis, B. oralis, B. corrodens, and B. genus (B. Disttasonis), B. vulgatus, B. thetaiotaomicron, B. ovatus, B. ureolyticus and B. gracilis Wait.

(2) Fusobacterium: such as F. nucleatum, F. necrophorum, F. varium, and Fusarium oxysporum (F. Mortiferum) and so on.

(3) Porphyromonas (Porphyromonas): such as P. asaccharolytica, P. endodontalis, P. gingivalis (P. Gingivalis).

(4) Prevotella.

1 Lactobacillus-producing bacteria: P. dentis, P. intermedia, P. loescheii, P. melarinogenicus, P. copporis and P. nigrescens.

2 non-product of P. aeruginosa: P. oris, P. buccae, P. oralis group, P. bivia , P. disiens and the like.

(5) Bilophila: such as B.wadsworthia.

(6) Sutterella wadsworthensis.

2, cocci: mainly have the genus Veillonella (Veillonella) and so on.

Gram-positive bacteria

1. Cocci: (1) Peptostreptococcus: such as P. magnus, P. anerobius, P. intermedius, tiny P. micros, P. aacaccharolyticus, P. prevotii, and the like.

(2) Microaerophilic streptococci.

2, Gram-positive Bacillus genus: mainly Clostridium, such as C. perfringenes, C. septicum, Novobacterium (C. .novyi), C.histolyticum, C. sporogenes, C. sordellii, C. tetani, Clostridium botulinum (c .botulinum), C. difficile, C. ramosum, C. bifermentans, C. clostridioforme, Clostridium clostridium (C) .fallax) and C. innocuum.

3. Gram-positive non-Bacillus sp.: (1) Actinomyces: such as A. israelii, A. naeslundii, Actinobacillus actinomycetes (A.naeslundii) A. odontolyticus), A. viscosus, A. neuii, A. meyerii, A. radingae and A. turicensis.

(2) Propionibacterium: mainly P. acnes and P. propionicum.

(3) Lactobacillus.

(4) Bifidobacterium: B. dentium and the like.

(5) Eubacterium: such as E. lentum, E. limosum, E. nodatum, etc. The most common of the oxygenated bacteria infections are the following five species:

1 Bacteroides fragilis group, mainly Bacteroides fragilis; 2 P. gingivalis and Porphyromonas genus; 3 nucleus Fusarium; 4 digestive streptococci; 5 Clostridium perfringens and Clostridium perfringens , oral cavity, nasal cavity, oropharynx, nasopharynx hide complex flora, they are different in different parts, usually called micro-ecological environment, the bacteria content in saliva is about 108 / ml, half of which is anaerobic bacteria, Mainly Weirong cocci, tartar and periodontal pocket containing anaerobic bacteria 1011 ~ 1012 / g, the amount of anaerobic bacteria in the gastrointestinal tract increased from top to bottom, the stomach contains only a small amount of lactobacilli; the lower intestinal ileum contains bacteria 108 / Ml, wherein the number of anaerobic and aerobic bacteria is equal; the stool contains 1011~1012/g of bacteria, 99.9% is anaerobic bacteria, and there are many kinds of anaerobic bacteria, including Streptococcus pneumoniae, Bacteroides, Clostridium anatipum Bifidobacteria, bacillus and lactobacilli, etc., the main pathogenic anaerobic bacteria in the upper respiratory tract are Streptococcus pneumoniae, Fusobacterium and Bacteroides, etc. The bacterial content in the vagina and cervix varies considerably, and can be 105. Between ~1011/ml fluctuations, and affected by the menstrual cycle, the main The anaerobic bacteria are Lactobacillus, and various anaerobic cocci, Bacteroides, Prionella and Clostridium are also common. The skin contains a large number of acne short-stick bacterins, but the skin of the perineal skin and parts of the lower limbs has a colon. Some bacteria in the flora, such as Bacteroides and Clostridium.

It should be pointed out that anaerobic bacteria are commonly found in the skin, oral cavity, nasal cavity and pharynx exposed to the air. There are two reasons for analyzing the cause:

1 Aerobic bacteria and facultative anaerobic bacteria present in these parts consume oxygen; 2 the position of the teeth, tonsil crypts and skin hair follicles is low, which is conducive to the reproduction of anaerobic bacteria in tissues, in addition, The content and type of anaerobic bacteria in different parts of the digestive tract are very different. Due to the presence of gastric acid, the amount of bacteria in the stomach is small. The intestinal peristalsis causes most bacteria to be sent to the lower intestine, thus explaining the bacteria in the small intestine. The phenomenon of less amount, the activity of the terminal ileum and colon is relatively poor, and the redox potential is low, so the bacterial content is high, and 99.9% is anaerobic bacteria, thus it can be seen that a large number of anaerobic bacteria are distributed in human skin. And mucosal surface, under certain conditions, anaerobic bacteria are easy to invade and cause infection, about 2 / 3 of anaerobic infection is mixed.

Pathogenesis

There is no definitive definition of anaerobic bacteria. It is generally considered that this type can only grow under low oxygen partial pressure, but in the air with 10% carbon dioxide concentration (18% oxygen) can not be on the surface of solid medium. Growing bacteria, most anaerobic bacteria do not contain catalase and cannot degrade hydrogen peroxide, and usually cannot destroy superoxide groups. However, clinically significant anaerobic bacteria often contain a small amount of superoxide dismutase. (SOD); Moreover, the tolerance of these anaerobic bacteria to oxygen is related to the content of SOD. According to the tolerance of anaerobic bacteria to oxygen, it can be divided into obligate anaerobic bacteria, facultative anaerobic bacteria and Microaerobic anaerobic bacteria, the latter refers to those types of anaerobic bacteria that grow poorly or not in an aerobic environment, but grow better in air with a carbon dioxide concentration of less than 10% or under anaerobic conditions. Oxygen bacteria include spores and spore-free, the latter can also exist in the form of spores, and the common pathogenic anaerobic bacteria that cause infection are as follows.

1. The defense function of the human body

Complete skin and mucous membranes are natural barriers to infection. Antibodies, complement systems, neutrophils and cellular immune responses are also important in preventing anaerobic infections. Some Gram-negative anaerobic bacteria can be used. Serum antibodies are directly killed. Neutrophils can kill anaerobic bacteria through oxidative and non-oxidative mechanisms. In addition, anaerobic bacteria may be more easily killed by macrophages. Experiments have confirmed that circulating antibodies and complements can be defended and Bacteremia associated with abdominal infection, and T cells can prevent abscess formation.

2. Pathogenicity of anaerobic bacteria

It is related to bacterial adhesion, invasiveness, toxins and enzymes produced, and virological factors such as bacterial surface components. Some anaerobic bacteria can use their toxins, capsules, and adhesion factors (such as pili can adhere to host epithelial cells). Enzymes or metabolites increase their pathogenicity. For example, Clostridium perfringens can produce a variety of powerful exotoxins and invasive enzymes, and has a capsule, which has a strong invasive ability and can hydrolyze the membrane. Phosphatidylcholine produces hemolysis, muscle necrosis and other lethal effects. Some strains still produce hemolysin, elastic cellulose, gelatinase, deoxyribonuclease, etc. Gram-negative anaerobic bacteria and aerobic bacteria are the same, and endotoxin is also produced. Some also produce neuraminidase, plasmin, hydrogen sulfide, hydrazine, ammonia and -glucuronidase, etc., lipopolysaccharide (LPS) is present on the cell wall of Bacteroides fragilis, but the core polysaccharide fraction of LPS Lack of 2-keto-3 deoxyoctanoic acid and heptose, the lipid part lacks -hydroxy myristic acid. Because these three are the main active part of endotoxin, their LPS activity is weaker than that of general Gram-negative bacilli. , Bacteroides fragilis can produce -lactam Enzymes, heparinase, hyaluronidase, DNase and neuraminidase, etc., such enzymes are closely related to pathogenicity. For example, -lactamase can degrade -lactam antibiotics, not only to protect themselves, At the same time, it can protect the symbiotic bacteria sensitive to -lactam antibiotics, thereby synergistically causing disease; heparinase can degrade heparin, promote coagulation, and easily form bacterial emboli; hyaluronidase can enhance the invasion and dissemination ability of bacteria. , Prevotellamelarinogenica and other anaerobic strains have high protein decomposition activity, and have effects on a variety of proteins, including casein, fibrin, collagen, immunoglobulin, etc., which can decompose connective tissue. Oxygen lesions can produce a large amount of ammonia in blood and exudate, which can dissolve mucosal epithelium, which is one of the predisposing factors of periodontal disease, Weirong cocci, bifidobacteria, true bacillus, short sclerotium, lactic acid Bacteria such as Bacillus are pathogenic bacteria with weak pathogenicity.

3. Pathogenesis of anaerobic infection

(1) Destruction of skin mucosal barrier function: such as surgery, trauma or certain disease states.

(2) Changes in the colonization position of the normal flora.

(3) Pathogenicity and bacterial count of anaerobic bacteria.

(4) Reduction of redox potential (pH lowering): It is beneficial to the reproduction of anaerobic bacteria in tissues, and the cause of pH decrease is mainly due to insufficient blood supply, tissue necrosis, or aerobic or facultative anaerobic bacteria. Vascular diseases affecting blood supply (including arteriosclerosis), malignant tumors (such as lymphoid hyperplasia or adjacent mucosal tumors, etc. due to easy local blockage, ischemia and hypoxia, tissue necrosis and mucosal damage are beneficial to anaerobic bacteria Reproduction), freezing, shock, edema, trauma (especially abdominal, pelvic and dental trauma), surgical operations (such as tooth extraction, etc.), foreign bodies, the presence of gas-producing bacteria, etc.

(5) Decreased human defense function: It can be seen under certain pathological conditions. In addition, anaerobic bacteria can further weaken humoral immunity and cellular immune function. Some anaerobic bacteria combine or consume opsonin to prevent the latter and non-anaerobic Bacteria (including anoxic anaerobic bacteria, microaerophilic anaerobic bacteria and facultative anaerobic bacteria) bind to phagocytic cells, and Capnocytophaga can cause reversible acquired neutrophils. Cell chemotactic function defects, in vitro experiments confirmed that under certain conditions, anaerobic bacteria can directly inhibit the function of neutrophils, macrophages and lymphocytes, under low pH conditions, by Bacteroides and other Gram-negative The short-chain fatty acids produced by anaerobic bacteria can inhibit the killing of neutrophils, and the interaction between Bacteroides fragilis and peritoneal macrophages can induce its procoagulant activity; cellulose deposition at the infected site reduces bacterial clearance. In summary, except for anaerobic spores infection, most anaerobic infections are endogenous, and pathogenic bacteria are often plural. For example, abdominal infections have an average of five different bacteria, three of which are Oxygen bacteria, two kinds of aerobic or facultative anaerobic bacteria, as mentioned above, all the lowering of the pH is beneficial to the occurrence of anaerobic infection, as well as diabetes, severe liver disease, cirrhosis, uremia, blood peroxidation Hydrogenase deficiency, hemorrhoids ulcers, human or animal bites, limb gangrene and other diseases, as well as long-term acceptance of immunosuppressive agents, aminoglycoside antibiotics, blood catalase deficiency corticosteroids, antimetabolites, radiation therapy and organs Patients such as transplants have an increased chance of developing anaerobic infections.

Anaerobic infection prevention

1. As much as possible to prevent the occurrence of reduced tissue oxidation-reduction potential.

2. Prevent normal anaerobic flora in the body: or introduce anaerobic bacteria into the wound, close the cavity, etc., wounds should be thoroughly debrided as soon as possible, remove foreign bodies and ineffective cavity, rebuild good blood supply; abdominal penetrating trauma, especially When the colon is involved, there are indications for the prevention of antibiotics. Chronic lesions such as chronic otitis media, sinusitis, and mastoiditis should be actively treated to prevent intracranial anaerobic infection, frail, unconscious or dysphagia. Attention should be paid to prevent inhalation when eating. Cardiac patients with valvular disease should undergo dental treatment. Prophylactic antibacterial therapy should be given during oral surgery. To prevent postpartum sepsis, premature rupture of membranes, prolonged labor and postpartum hemorrhage should be noted.

Timely treatment of infections is limited to specific sites prior to diffusion, can prevent serious anaerobic infections, carefully clean the wounds, remove foreign bodies and early antibiotic treatment is an effective preventive measure before and after abdominal surgery and surgery Intravenous antibiotics are used to prevent infection.

Anaerobic infection complications Complications pneumonia phlebitis septic shock

Concurrent pneumonia, thrombophlebitis, intestinal infection with intestinal perforation, gynecological infection with sepsis sepsis, shock, renal failure, severe myocardial abscess.

Symptoms of anaerobic infection common symptoms secondary infection leukocytosis appendix infection gangrene diarrhea abdominal pain low fever gallbladder empyema lung infection peritonitis

Anaerobic infection can occur in any part and organ, but infection in the chest, abdomen and pelvis is more common, accounting for 70% to 90% of infections in these areas, but 1/3 to 2/3 are mixed infections.

Central nervous system infection

Focal suppurative infections, such as brain abscess and subdural empyema, are often associated with anaerobic infections. Conversely, epidural empyema and meningitis caused by anaerobic bacteria are rare.

(1) Brain abscess: Anaerobic bacteria are the main pathogens of brain abscess, and the invasion pathway and primary lesion are:

1 otitis media (often chronic) and mastoiditis are the most common, directly spread and involve the brain, brain abscess is often located in the temporal lobe or cerebellum.

2 blood source dissemination caused by brain abscess, often multiple sexual, common in the gray matter and white matter junction, mostly in the frontal, parietal and occipital, rarely seen in the temporal lobe or cerebellum, the infection can originate from lung or chest infection Including subacute or chronic lung abscess, bronchiectasis, empyema, necrotizing pneumonia, etc.

3 sinusitis, pathogenic bacteria often directly spread and cause brain abscess, mainly found in frontal and temporal lobe, pathogenic bacteria are most common with Bacteroides.

4 other traumatic, congenital heart disease (right to left shunt), oral or dental infection, tonsil or pharyngeal inflammation, infective endocarditis, urinary tract infection, intra-abdominal abscess, etc., the most pathogenic bacteria Commonly known are Bacteroides, Prionella, Fusiform and Streptococcus pneumoniae, among which Bacteroides fragile and other bacilli are more common, Clostridium and actinomycetes occasionally, clinical manifestations are mainly space-occupying lesions, headache , mental disorders, lethargy or dullness, cranial nerve palsy, optic disc edema, etc., there may be hemiplegia, aphasia, seizures, etc., symptoms of toxemia may not be obvious, not necessarily fever, EEG, brain ultrasound, radioactivity Radionuclide scanning, brain CT, MRI, cerebral angiography, etc. are helpful for diagnosis and localization. Cerebrospinal fluid examination shows increased protein, normal sugar, and mild increase of white blood cells. If abscess breaks into the ventricle, suppurative meningitis can quickly appear. Symptoms of increased intracranial pressure.

(2) meningitis: anaerobic bacteria rarely cause meningitis, anaerobic meningitis only accounts for about 1% of bacterial meningitis, but there are also individual reports of 9%, the primary lesions with chronic otitis media and / or milk The most common form of sudden inflammation, followed by surgery (or laminectomy), pathogenic bacteria are often Fucoid, fragile bacillus, anaerobic cocci and Clostridium perfringens, head and neck malignant The anaerobic meningitis caused by secondary infection of the tumor and the pathogen caused by trauma are more common in Clostridium perfringens, but the bacillus is rare, and anaerobic septicemia can be complicated by meningitis. The incidence is not high, the incidence of neonatal anaerobic septicemia and meningitis is high, the pathogen often comes from the mother's birth canal, or the mother has a history of amnion, the pathological changes in addition to meningitis, acute necrotizing vasculitis Common, there may be thrombosis, clinical manifestations and general suppurative meningitis are no different, the severity of the disease, meningitis caused by short saplings can be stroke-like or chronic meningitis, cerebrospinal fluid cells increased to monocytes Mainly.

(3) Others: Anaerobic bacteria can cause subdural empyema, epidural empyema, spinal epidural abscess, ependymitis, central nervous system thrombophlebitis, cerebrospinal fluid shunt infection (a few can be Caused by more acne short-stem vaccine in hair follicles or sebaceous glands).

2. sepsis and endocarditis

(1) Septicemia: Previous studies have suggested that anaerobic bacteria in sepsis can be as high as 10% to 15%, and the incidence of neonatal anaerobic septicemia is particularly high, but in recent years, the incidence of anaerobic septicemia Down to 5% or less, which may be associated with anti-anaerobic activity drugs that are widely used to prevent or treat early anaerobic infections or mixed infections, atherosclerosis, alcoholism, cirrhosis, diabetes, malignancy, hemorrhoids and The end stage of nephropathy (peritoneal dialysis, nephrectomy, kidney transplantation) is easy to cause anaerobic septicemia, anaerobic septicemia of clinical importance, 2/3 ~ 3 / 4 by Gram-negative anaerobic bacteria Caused by the more common Bacteroides fragile; followed by Streptococcus pneumoniae (about 10%) and Clostridium (5% ~ 10%); and with the improvement of technology, Lepidhrix, moon-shaped single Selenomonas and Anaerobiospirillum have also been found in blood cultures. Anaerobic bacterial sepsis is often secondary to focal infections, fragile Bacterial sepsis, most of which are invaded by the intestines. Partly from the female reproductive tract, by the gastrointestinal tract The blood culture of the invaders is often positive and often a variety of bacterial infections. However, it is rare for the female genital tract invaders to have multiple positive blood cultures, but a variety of bacterial infections are common, and the clinical manifestations are similar to aerobic septicemia, often with fever. Increased white blood cell count, septic shock (30%) and disseminated intravascular coagulation, the incidence of jaundice is high, up to 10% to 40%, easy to migrate migratory suppurative lesions (10% to 28%) septic thrombotic vein Inflammation (5% to 12%), sepsis can be violent and accompanied by high mortality, such as Clostridium perfringens sepsis, often hemolysis, jaundice, shock and renal failure, critically ill, and partial sepsis has also been discovered in recent years. The condition is mild, there is no serious toxemia, and it is benign. The course of the disease is self-limiting. It can be recovered without antibiotic treatment. Some female patients and newborn blood cultures have confirmed Clostridium perfringens, but it is also mild. .

(2) Endocarditis: The incidence of endocarditis caused by anaerobic bacteria accounts for 1.5% to 10% of endocarditis, and there is an increasing trend. Common pathogens are Bacteroides, fusiform Bacillus, anaerobic spores, keratinized short stalks, micro-aerobic bacteria and anaerobic streptococci, the primary lesions are mostly in the oropharynx, clinical manifestations are different from general subacute bacterial endocarditis, more common in In patients without primary heart disease, anaerobic bacteria invade normal valves, often causing embolism, valve destruction, and more serious complications such as myocardial abscess or destruction or perforation of valves and other supporting structures, often causing heart failure, such as Those caused by anaerobic or microaerobic streptococcus are similar to Streptococcus viridans, and can also invade the valve of the original lesion.

3. Respiratory infection

(1) Upper respiratory tract infection: the upper part of the respiratory tract is connected to the pharynx, the bacterial species are basically similar, and the various aerobic bacteria are the most diverse; the anaerobic bacteria are more common than the aerobic bacteria, and the common ones are Fusarium and digestion. Streptococcus, the second is Bacteroides, in the tooth and gum infection, the production of meseria is an important pathogen, but because of its complex culture conditions are not easy to detect, the most common infection is chronic sinusitis, tonsil Peripheral abscess, periodontal infection, chronic otitis media, mastoiditis, etc.

(2) Intrathoracic infection: The lower respiratory tract anaerobic infection mainly manifests in four clinical conditions, namely aspiration pneumonia, lung abscess, necrotizing pneumonia and empyema. The occurrence of these various infections is often inhaled by the contents of the oropharynx. Caused by more changes in consciousness and local defense function, such as bronchial obstructive lesions (foreign body, lung cancer, etc.), hypoxia, smoking, alcoholism, esophageal obstruction, upper respiratory tract purulent lesions, etc., causing secretions or pus Liquid is easy to inhale, in addition to inhalation (most common), lung infection can also be blood-borne, from distant infections (more common in pelvic or intra-abdominal) or septic thrombosis The anaerobic pleural infections are mostly mixed, and the bacterial species range from two to nine species, including aerobic and facultative bacteria, but they can also be obtained by pure anaerobic culture, and various types of anaerobic bacteria. Bacillus (especially Bacteroides), Przetia, Fusobacterium (H. nucleatum) and Streptococcus pneumoniae are common, and Gram-positive non-Bacillus and Clostridium are relatively rare.

1 pneumonia: about 90% of the main pathogens of aspiration pneumonia are anaerobic bacteria, generally more acute, due to the characteristic manifestations of anaerobic pulmonary infection (skunk, tissue necrosis, etc.) are often absent Ignore, such patients often have unconsciousness, the history of inhalation can be identified, and the treatment effect is often good. It is worth noting that aspiration pneumonia occurs in the hospital environment (especially after antibiotic treatment), due to mouth The normal flora of the pharynx changes, often with facultative Gram-negative bacteria transplantation, so the inhalation bacteria are different from normal, often Enterobacteriaceae bacteria and Pseudomonas.

2 lung abscess: the disease is slower, most have a history of inhalation, disturbance of consciousness and difficulty in swallowing or obvious history of tooth infection. The lesion is more common in the descending lung segment, the dorsal segment of the upper lobe, the tip and posterior segment of the lower lobe, and the two lungs. The bottom of the lower leaves, etc., the pathogenic bacteria are mostly mixed (half of the anaerobic bacteria can be purely cultured), common anaerobic bacteria are Clostridium, Bacteroides, Melostococcus, Streptococcus pneumoniae, micro-needs Oxygen bacteria, short rod vaccine, true bacillus, Weirong cocci, etc.; aerobic bacteria are often Staphylococcus aureus, Streptococcus and Escherichia coli, Klebsiella and other Gram-negative bacilli, purulent stench is about 1/ In the case of 4 cases, the average course of the patient's medical treatment has been about 2 weeks, often with anemia, weight loss, low fever, infection is often characterized by insidious, an average of 12 days of abscess formation (as early as 7 days after inhalation), abscess The diameter is more than 2cm.

3 necrotizing pneumonia: is a prone to severe suppurative pneumonia, with multiple necrosis and small cavity formation, mainly found in a lung lobe or lung segment, but can rapidly spread lung tissue destruction and a large number of carrion tissue shedding, forming a "lung Gangrene", clinically often have high fever, rancid purulent sputum, empyema found in more than half of the cases; pathogenic bacteria and general non-neoplastic pneumonia similar, more than 2 / 3 cases can be obtained pure anaerobic culture, most of the empyema at the same time Accompanied by lung parenchymal lesions, mainly caused by inhalation, a small number can be formed from the subgingival abscess through the spread of the diaphragm, often high fever, increased white blood cells, pathogenic bacteria and lung parenchymal lesions are the same, thoracic purulent exudation The liquid is not easy to withdraw, often requires surgical drainage to cure, recovery is very slow, often takes several months.

4. Intra-abdominal infection

The normal intestinal tract contains a large number of anaerobic bacteria, and intra-abdominal infections are often associated with intestinal flora contamination, and therefore have the following characteristics:

1 Anaerobic bacteria have a high separation rate. Commonly known are Bacteroides fragilis and other Bacteroides, Fusobacterium, Clostridium perfringens, Streptococcus pneumoniae and True bacilli. The pathogens depend on the infection or surgical site, the upper digestive tract. Containing a small amount of facultative Gram-positive bacteria from the oropharynx, Escherichia coli and obligate anaerobic bacteria are relatively few, the lower part of the ileum is the transition zone, the anaerobic and facultative bacteria are half, and the colon is anaerobic. More, especially the type of bacilli, anaerobic bacteria greatly exceed the facultative bacteria, such as E. coli, such as 1000 to 1 ratio, so upper gastrointestinal damage (such as perforation or trauma of ulcer disease), often only a small amount of bacteria into the abdominal cavity The risk of infection is small; however, colonic perforation often releases a large number of bacteria, causing a high risk of infection. Peritonitis and intra-abdominal abscess are 95% related to anaerobic bacteria. The most common is a mixture of aerobic and anaerobic bacteria. Infection, primary peritonitis caused by only one facultative strain (such as E. coli) is only seen in cirrhosis.

2 is often a mixed infection of a variety of bacteria, on average, each specimen can be separated into five kinds of bacteria, including anaerobic bacteria and aerobic bacteria (or facultative bacteria), the separation rate of anaerobic bacteria is high, the main anaerobic bacteria are fragile Bacteroides, followed by Clostridium anaeroides and anaerobic cocci; aerobic bacteria are more common with Enterobacteriaceae (such as Escherichia coli, Klebsiella, Proteus) and Pseudomonas aeruginosa, predisposing factors or The original diseases are trauma, colon cancer, pancreatic cancer and kidney cancer, intestinal surgery, perforation of the appendix, cirrhosis with primary peritonitis, infection after peritoneal dialysis, intestinal vascular disease or intestinal obstruction, chronic ulcerative colitis Before the operation, the aminoglycoside antibiotics are prepared for intestinal disinfection. The intraperitoneal infection may manifest as peritonitis (diffuse or localized), and then form an abscess, which may be located in the abdominal cavity, retroperitoneum or internal organs. Some cases are accompanied by bacteremia, and Bacteroides is more common.

(1) Liver abscess: Liver abscess pus culture about 40% ~ 60% can be free of bacterial growth, bacteriological examination confirmed that most of them are anaerobic bacteria, common pathogenic bacteria are Bacteroides, Fusobacterium nucleatum and anaerobic Streptococcus, anaerobic spores, etc., and often mixed with aerobic bacteria infection, patients often have gastrointestinal surgery, inflammation, perforation history, and most of the primary disease such as arteriosclerosis, diabetes or biliary tract disease, anaerobic bacteria The clinical manifestations and diagnosis of liver abscess are the same as those caused by aerobic bacteria. Clinically, there are fever, hepatomegaly, jaundice and toxemia, serum alkaline phosphatase value, liver B-mode ultrasound, radioactivity. Radionuclide liver scan, CT, hepatic angiography and other conditions can be used to help diagnose.

(2) biliary tract infection: normal gallbladder wall and bile generally have no bacterial growth or contain a small amount of non-pathogenic bacteria, but about 50% of patients with stone disease may have bacterial colonization in the gallbladder, mainly Escherichia coli and enterococci, especially in the elderly. When the stones cause obstruction of the common bile duct, the positive rate of bacterial culture is increased. In anaerobic, anaerobic streptococci, Bacteroides and Clostridium anaestheides are more common (the latter can cause severe gas gangrenous cholecystitis, early in comparison More common), the latter detection rate of up to 20%, especially in the gallbladder empyema, in elderly patients with diabetes, cholecystitis can be emphysema, systemic toxemia symptoms are heavier, X-ray examination can be seen in the gallbladder There is obvious gas formation or gas-liquid level, mostly caused by Clostridium perfringens.

(3) appendicitis: E. coli, aerobic streptococcus, bifidobacteria and gram-negative anaerobic bacteria (including Bacteroides, fusiform, etc.) can be cultured in normal appendix, and pathogenic bacteria of appendicitis account for anaerobic bacteria The main status, especially the fragile bacillus is more common, accounting for more than 70%, the more serious the appendix inflammation, the higher the positive rate of anaerobic bacteria, the simple rate of simple appendicitis is 36%, the suppurative is nearly 70%; gangrenous and perforating More than 80%.

(4) Intestinal infection: See C. difficile infection for details.

(5) Others: Anaerobic bacteria can cause diverticulitis (mostly mixed infections of anaerobic and aerobic bacteria), pancreatic abscess (low incidence of anaerobic infection in pancreatitis), spleen abscess (mostly majority) Sex, may be blood-borne, the incidence is not high), gastric cellulitis or emphysema necrotic inflammation.

5. Female reproductive tract and pelvic infections

Almost all female reproductive tract infections caused by non-sexual transmission include anaerobic infections. Common pathogens include Streptococcus pneumoniae, Przetia (especially Plutobacillus and P. syringae), Pseudomonas , Clostridium (including Clostridium perfringens) and Bacteroides fragile is not common in intra-abdominal infection, patients with intrauterine devices are prone to actinomycetes and Eubacterium modatum infection, The predisposing factors that are beneficial to the infection caused by the above-mentioned bacterial invasion are: local blood supply deficiency; presence of damaged or necrotic tissue; presence of foreign bodies such as intrauterine devices; exogenous microbial growth and reproduction causing tissue destruction, creating for the invasion of normal flora of the lower genital tract Conditions; pregnancy; abortion; malignant tumors and uterine fibroids; radiation therapy; obstetrics and gynecology surgery, cervical electrocautery, etc., anaerobic bacteria can cause a variety of female reproductive tract infections, including endometritis and uterine empyema, Uterine myositis, collateral connective tissue inflammation, pelvic cellulitis and abscess, pelvic thrombophlebitis, labia abscess, vestibular gland inflammation and abscess, vaginitis, vaginal wall abscess, salpingitis or pus , ovarian abscess, wound infection after cesarean section or hysterectomy, septic abortion, puerperal fever, chorioamnionitis, etc., uterine gas gangrene caused by Clostridium perfringens is a rare serious complication, patient poison The blood is extremely severe, the uterine muscle is extensively necrotic, resulting in uterine perforation, and the mortality rate is high. Most female reproductive tract infections are mixed infections, anaerobic bacteria and aerobic bacteria doping.

6. Urinary tract infection

Although the urethra, perineum, vagina and external genital tract can have many aerobic and anaerobic bacteria, and bacteria can easily enter the bladder, but anaerobic bacteria cause less urinary tract infection (1% to 9%), it is worth Note that the urine samples collected from the urine samples may be from the normal urethra, the count can reach 103 ~ 104, or even more, it can not be considered as the basis of infection, urine specimens should be obtained from the suprapubic bladder puncture, anaerobic Urinary tract infections caused by bacteria include urethritis, inflammation around the urethra, cellulitis and abscess around the urethra (may be associated with necrosis or multiple spasm), urethral gland inflammation (including necrotic and emphysema), prostatitis (occasionally Necrotic and empyema), migratory kidney infection (usually accompanied by empyema in sepsis), perirenal abscess, renal pelvis empyema, retroperitoneal empyema, nephrectomy wound infection, kidney transplantation infection, suppurative thrombophlicular phlebitis, Bladder gangrene, perineal abscess or gangrene, gas gangrene in various parts of the urinary tract, testicular abscess, etc., urinary tract anaerobic infection often accompanied by kidney stones, malignant tumors, urinary tract obstruction, renal tuberculosis and congenital urinary tract anatomy, common Pathogenic bacteria Bacteria, and Lactobacillus, Clostridium nucleus, Clostridium perfringens, etc., often have aerobic bacteria mixed, the latter is the normal intestinal flora (such as Escherichia coli, Klebsiella, Proteus), patina The sources of anaerobic urinary tract infections such as Pseudomonas and Staphylococcus epidermidis are:

1 The path of the urinary tract itself causes the invasion of the endogenous flora to cause infection; 2 caused by the adjacent organs such as the uterus, the intestines, etc.; 3 blood-borne dissemination, urethral injury (such as squeezing the urethra, indwelling catheter) Etc.) can make bacteria from the urethra into the bladder, shock and urethral obstruction are beneficial to anaerobic hyperplasia.

7. Bone and joint infections

Anaerobic myelositis is rare, anaerobic osteomyelitis is divided into actinomycetes and non-actinomycetes. Actinomycete osteomyelitis is mainly found in the jaw and vertebrae, followed by ribs and skulls. , long bones, short bones, etc., can be accompanied by other mixed infections of anaerobic bacteria and aerobic bacteria, mostly caused by the direct spread of nearby infections (such as periodontal infection, sinusitis, trauma or malignant tumor infection), infection The procedure is often subacute or chronic, with typical lumps in the ankle or neck, and sinus with frequent pus discharge and "sulphur granules". Non-acticulating anaerobic osteomyelitis with anaerobic and microaerobic Streptococcus is more common, followed by Clostridium, Bacteroides fragilis, Melanella producing bacteria, other bacilli, Clostridium, etc., can be transmitted by nearby infection or blood supply, prone to diabetes patients Anaerobic bacteria and aerobic bacteria osteomyelitis are not easy to distinguish in clinical, but the systemic symptoms of anaerobic infection are relatively mild. Half of the patients have malodorous secretions, necrotic tissue shedding, soft tissue gas accumulation and abscess formation, etc. Oxygen bacteria also cause less suppurative Inflammation, caused by Clostridium, Bacteroides fragilis and Bacteroides melanogis, Streptococcus pneumoniae, Clostridium, etc., involving the larger joints, followed by knees, hips, elbows, chest locks, shoulders, sputum, etc. Different from osteomyelitis, culture is often obtained from pure culture of anaerobic bacteria. The sterno-lock joint and ankle joint are the predilection sites of anaerobic arthritis. Therefore, in the process of sepsis, joint inflammation of the above-mentioned parts occurs, especially when it is oral. When the pharyngeal infection is a bacterial invasion portal, it should be considered that the lethal Clostridium is a possible pathogen, pus odor or local gas accumulation, and the general culture is often caused by anaerobic bacteria.

8. Skin and soft tissue infections

The predisposing factors for anaerobic skin and soft tissue infections are traumatic, ischemic and surgical pathogens are mostly mixed, and often endogenous, in the body's susceptible to anatomical parts, such as intestinal or pelvic surgical wounds, Perineum, hemorrhoids and other places have a greater chance of being infected, characterized by frequent rancid secretions, gas production, extensive tissue necrosis, and a tendency to extend to the subcutaneous tissue and fascial surface to form sinus, mostly by aerobic bacteria and anaerobic Synergistically caused by oxygen bacteria, some anaerobic bacteria can cause the following special clinical syndromes.

(1) Progressive bacteria co-infectious gangrene: caused by the synergistic action of micro-aerobic streptococci and Staphylococcus aureus, Staphylococcus aureus can be found in the necrotic center, while the former is detected in the marginal part of the expansion of inflammation, often secondary to Intraperitoneal infection, after laparotomy, the onset is slower, initially shallow and small ulcers, gradually develop into necrotizing ulcers of skin and subcutaneous tissue, the symptoms of systemic poisoning are mild, and three obvious skin bands are visible locally: central ulcer, The marginal area is rude and rough; the peripheral purple induration area; the outermost layer is the erythema area, and the lesion expands outward with severe pain.

(2) Synergistic necrotizing cellulitis: Unlike the former, the disease progresses rapidly, with symptoms of systemic poisoning, common in the perineum or lower limbs, most patients have diabetes or other diseases with insufficient blood supply, connective tissue necrosis on the skin and fascia Rapid progress, thin and dirty secretions, local pain and fever, mostly mixed infection, common pathogens are Streptococcus pneumoniae, Bacteroides and aerobic Gram-negative bacilli, etc., high mortality, Clostridium perfringens The resulting gas-breaking cellulitis is a kind of connective tissue inflammation with mild symptoms of systemic poisoning and a large amount of gas. It is caused by Streptococcus pneumoniae, Bacteroides or Escherichia coli. The onset is slow and the disease progresses slowly. The pain is not enough, and the muscles are not enough to distinguish it from the gas gangrene. It is common in war wounds or surgical wounds.

(3) Chronic sinus sinus ulcer: a deep and painless subcutaneous infection, mostly caused by microaerobic streptococcus, most of which occur after surgery, trauma or infected lymph node drainage, the edge of the initial ulcer is curled, with a majority The sinus tract, which eventually erodes the covered skin, forms a secondary ulcer that lasts for months, even years.

(4) necrotizing fasciitis: a critical infection involving the deep fascial surface, which can occur after minor trauma or surgery, but can also be primary, adjacent tissues often involved and cause gas Cellulitis, skin gangrene, etc., often have severe toxemia symptoms, high mortality, digestive streptococcus is the most common pathogen, but can also be caused by group A streptococci or Staphylococcus aureus.

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diagnosis

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(1)(Capnocytophaga)(Leptotrichia buccalis)

(2)(neutropenic colitis)

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(7)(Eikenella corrodens)(Pasteurella spp)

Differential diagnosis

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