Staphylococcus infection
Introduction
Introduction to staphylococcal infection A purulent infection of humans and animals caused by Staphylococcus gram-positive cocci, classified into pathogenic Staphylococcus aureus and conditionally pathogenic Staphylococcus epidermidis, in addition to Staphylococcus aureus. Staphylococcus aureus can produce a variety of exotoxins and enzymes, so it is highly pathogenic and is a common bacterial infectious disease. It is often caused by skin and soft tissue infections, and can also lead to serious illness, life-threatening sepsis, endocarditis. Pneumonia, meningitis, etc.; in addition can cause foreign body related infections, urinary tract infections, osteomyelitis, arthritis, enteritis and so on. basic knowledge Sickness ratio: 5% Susceptible people: no special people Mode of infection: non-infectious Complications: osteomyelitis endocarditis
Cause
Causes of staphylococcal infection
Bacterial toxins (30%):
(1) Hemolysin: Staphylococcus aureus can produce four different antigenic forms of hemolysin, , , and , all of which can produce complete hemolysis, and hemolysin can damage platelets, macrophages and white blood cells. Vascular smooth muscle contraction leads to local tissue ischemic necrosis.
(2) leukocidin: killing leukocytes and macrophages or destroying their functions, so that bacteria can still grow in cells after being phagocytosed.
(3) Enterotoxin: For the production of exotoxin in food poisoning, there are at least six kinds of A, B, C1, C2, D and E. Oral administration can cause vomiting and diarrhea.
(4) Epidermolytic toxin: This toxin can cause the superficial epithelial detachment of the epidermis to produce symptoms such as bullous pemphigus.
(5) Toxic shock syndrome toxin (TSST) is produced.
(6) Producing rash toxin: It is produced by phage group II type 71 Staphylococcus aureus, and there is a clinically scarlet fever-like rash.
Enzyme (30%):
Staphylococcus can produce a variety of enzymes such as protease, lipase and hyaluronidase. The pathogenic effect of these enzymes is not clear, but it has the function of destroying tissues, which may promote the spread of infection to surrounding tissues. In addition, there are several enzymes. Related to pathogenesis and drug resistance.
(1) Plasma coagulase: causes fibrinogen in plasma to become fibrin, deposits on the surface of the cells, hinders the phagocytosis of phagocytic cells, and facilitates the formation of infectious thrombosis.
(2) -lactamase: Inactivated -lactam antibiotics.
(3) Hyaluronidase: This enzyme hydrolyzes the matrix-hyaluronic acid between human connective tissue cells to spread the infection.
(4) lipolytic enzyme: Staphylococcus aureus can produce several lipolytic enzymes, which act on plasma and fat and oil on the surface of the skin, which is beneficial to bacteria invading human skin and subcutaneous tissue.
(5) Others: There are still staphylokinase, catalase, and fibrinolytic enzymes.
Cellular antigen (20%):
(1) capsular antigen: Some strains of Staphylococcus aureus have obvious capsules, which increase virulence, and the body can produce corresponding antibodies. Protein A (aggregate agglutinogen A) is a component of the cell wall of Staphylococcus aureus. Present in 90% of Staphylococcus aureus, protein A binds to the Fc fragment of IgG and has anti-therapeutic and anti-phagocytosis functions.
(2) Cell wall acid: It is a specific antigen, and the wall acid composition of Staphylococcus aureus, Staphylococcus aureus and S. cerevisiae is different.
Regulation of virulence genes (10%):
The regulation of virulence genes of Staphylococcus aureus is extremely complicated. Due to various environmental factors and bacterial products, the agr gene and sar gene are currently studied. These two genes can up-regulate the expression of bacterial secreted proteins and reduce cell wall-associated proteins. Synthetic, Staphylococcus resistance: Staphylococcus is one of the most resistant pathogens, and the genus has almost all known resistance mechanisms, except for vancomycin and norvancomycin. All antibacterial drugs are resistant.
(1) Resistance changes: Before the 1960s, penicillin was the most effective antibiotic for the treatment of staphylococci. At present, about 90% of the clinically isolated staphylococci in Shanghai and Beijing are due to the production of -lactamase (penicillinase). Penicillin-resistant, these strains are generally sensitive to the combination of oxacillin, methicillin, most cephalosporins and -lactams and -lactamase inhibitors, and methicillin-resistant gold found in the early 1960s. The bacteria (MRSA) are resistant to all -lactams. In the 1980s, gentamicin was also an effective drug for the treatment of MRSA infection. Currently, the resistance rate of MRSA to gentamicin has exceeded 50%. Staphylococcus in the late 1980s Highly sensitive to fluoroquinolones, used as a retention drug for the treatment of MRSA infection, but now more than 80% of MRSA and MRSE are resistant to fluoroquinolones. In 1996, the first vancomycin-mediated Staphylococcus aureus was isolated. The MIC is 8-16 g/ml. Although staphylococcus resistant to vancomycin has not been found in China, two strains of staphylococcus resistant to vancomycin have been reported abroad, and the resistance of epiphylis is also serious. Table separated outside the hospital The -lactamase produced by Staphylococcus aureus is >80%. The resistance mechanism is also controlled by the plasmid. The strain of the enzyme produced by the rotulin is less, and the amount of enzyme produced is also small. All kinds of coagulase-negative staphylococci can be used. Oxycillin-resistant, 30% to 50% of the strains isolated from the hospital are resistant to methicillin, but also to penicillin, gentamicin or other aminoglycosides, erythromycin, clindamycin The drug resistance spectrum is similar to that of Staphylococcus aureus.
(2) Mechanism of resistance:
1 production of inactivated enzymes and modified enzymes: staphylococcus produced by penicillin can destroy a variety of penicillin antibiotics, some strains with high enzyme production can be expressed as resistant to oxacillin, the production of aminoglycoside modifying enzyme can be inactivated Aminoglycosides make the strain appear to be resistant to aminoglycosides, and staphylococci can also produce acetyltransferase to inactivate chloramphenicol and resist it.
2 target position change: penicillin binding protein (PBP) is a transpeptidase involved in the synthesis of staphylococcal cell wall. The combination of -lactam antibiotics can destroy cell wall synthesis. Staphylococcus has four PBPs and -inner Amide antibiotics have good affinity; but the mecA gene on the chromosome of methicillin-resistant Staphylococcus can encode a new penicillin-binding protein PBP2a (PBP2a), which has low affinity for -lactam antibiotics. It can maintain the cell wall synthesis of bacteria in a high concentration of -lactam environment, and make the bacteria be resistant. The methicillin-resistant Staphylococcus aureus and methicillin-resistant strains are referred to as MRSA and MRSE, respectively. The drug mechanism is the same. In addition to resistance to methicillin, these resistant bacteria are resistant to all penicillins, cephalosporins and other -lactam antibiotics, as well as to quinolones, tetracyclines, and certain aminoglycosides. Antibiotics, chloramphenicol, erythromycin, lincomycin resistance rate is also very high (>50%); for rifampicin, coumamycin (also known as coumarin), fosfomycin Certain aminoglycosides The sensitivity of antibiotics (Amikacin, Netilmicin, etc.) is relatively high. In recent years, the proportion of methicillin-resistant Staphylococcus in clinical isolates of Staphylococcus has increased. The mechanism of MRSA sensitivity to vancomycin is complicated. It does not have the vancomycin resistance genes van A, van B and van C. It is speculated that the drug resistance mechanism may be related to the bacterial cell wall synthesis. The study found that the cell wall of this strain is twice as thick as the similar strain, and the PBPS is normal. Three times higher, the interstitial precursor production is also increased by three times. These three characteristics cause the bacteria to increase the tolerance to vancomycin. The DNA gyrase target position change and the topoisomerase IV mutation are Staphylococcus to quinolones. The main mechanism of drug resistance, in addition, Staphylococcus can also change the target of folic acid inhibitors such as sulfa drugs, rifampicin, mupirocin, macrolides and lincomycins. Resistance.
3 efflux effect: Staphylococcus can excrete intracellular tetracyclines, macrolides and clindamycin and are resistant to these drugs.
Pathogenesis
Although Staphylococcus aureus can produce many toxins and enzymes, and cause various infections, strictly speaking, the bacteria, like S. epidermidis and rot, are still a conditional bacterium that coexists in parasitic parts. In the case of a sound function, it is not harmful. Even if the bacteria invade the deep tissues beyond the parasitic range, they can be swallowed up by white blood cells, macrophages, serum specific and non-specific factors, or are limited to dispersed areas. Abscess, but if there is a low immune function (such as granule cell deficiency, severe underlying disease) or skin mucosal barrier damage (such as skin damage, interventional medical measures), it may lead to serious S. aureus infection, at this time, bacteria Inoculation from the colonization site to the damaged skin mucosa causes local infection of the soft tissue of the skin such as carbuncles, etc., the local spread of the infection causes paralysis, cellulitis, impetigo or wound infection, and the bacteria can also enter the blood and spread to the distal organs. , sepsis, bacterial endocarditis, osteomyelitis, renal pelvis, septic arthritis, epidural abscess, etc., even if the bacteria do not invade the bloodstream, bacterial toxicity Can also cause local and systemic disease manifestations or syndromes, such as toxic shock syndrome, scalded skin syndrome and enterotoxin gastroenteritis, many toxins of Staphylococcus aureus such as TSST1, Ses for the need to present antigen Cell-treated superantigens that stimulate large amounts of cytokines such as IL-1, IL-6, IL-8 and tumor necrosis factor alpha (TNF), leading to systemic inflammatory response syndrome (SIRS), Finally, it causes septic shock. Coagulase-negative staphylococci are mainly conditional pathogens. The pathogenicity is related to low immunity and foreign body implantation. The presence of foreign bodies seriously impairs the function of phagocytic cells, and foreign bodies such as intravenous catheters are quickly Containing fibrinogen, fibronectin and other serum components, these serum components recognize adhesion molecules through bacterial surface components to adhere to staphylococci, and produce glycocalyx (polysaccharide protein complex, glycocalyx) to further consolidate bacterial adhesion, colonization, hospital-acquired Endocarditis is often associated with intravenous catheters. Long-term indwelling catheters cause endocarditis in an animal model similar to endocarditis. Heart valve damage the pipe surface, is formed on the non-bacterial valve thrombus, lead to bacterial infection adhesion.
Prevention
Staphylococcal infection prevention
In order to prevent the occurrence and prevalence of staphylococcal infection, the following points should be noted:
1 Strengthen labor protection, keep the skin clean and complete, and avoid trauma;
2 timely and effective treatment of patients with staphylococcal infection, reasonable treatment of carriers to remove and reduce the source of infection;
3 Strictly implement disinfection and isolation measures for neonatal rooms, burn wards, surgical wards, etc., and cut off the route of transmission;
4 actively treat or control chronic diseases such as diabetes, blood diseases, liver cirrhosis, etc., especially those with neutropenia, and correct various immune defects, protect susceptible populations, anti-staphylococcal vaccine can improve cell phagocytosis and grapes The survival rate of the cocci infection model may be beneficial in preventing staphylococcal infection.
Complication
Staphylococcal infection complications Complications, osteomyelitis, endocarditis
Staphylococcus can infect any part of the body, and the symptoms depend on the part of the infection. The performance of infection can range from very light to life-threatening. Under normal circumstances, staphylococcal infection produces enveloping empyema, such as abscesses and pustules ( and ), Staphylococcus can spread through the blood and cause internal organ abscesses (such as the lungs) and bone infections (osteomyelitis) and Endocardial, heart valve infection (endocarditis).
Symptom
Staphylococcal infection symptoms common symptoms meningitis bacterial endocarditis pericarditis mastoid inflammation sepsis
Staphylococcus aureus can cause skin and soft tissue infections, sepsis, pneumonia, endocarditis, meningitis, osteomyelitis, food poisoning, etc., in addition to causing pericarditis, mastoiditis, sinusitis, otitis media, toxic shock syndrome Etc., in addition to causing sepsis, endocarditis, etc., can also lead to urinary tract and skin infections, Corynebacterium mainly cause urinary tract infections, and its pathogenesis can be divided into two major clinical manifestations Types of.
1. Disease caused by toxins
(1) Staphylococcus gastroenteritis: Staphylococcus aureus contaminates starchy foods (such as leftovers, porridge, rice noodles, etc.), milk and dairy products, fish, meat, eggs and other foods, at room temperature (about 22 ° C) Proliferate to produce heat-resistant enterotoxin (exotoxin), 100 ° C, 30 min can only kill Staphylococcus aureus can not destroy toxins, the latter can cause nausea, vomiting, middle and upper abdominal pain, diarrhea and other symptoms, usually vomiting, The vomit can be biliary; the diarrhea is watery or loose, and the body temperature is mostly normal or slightly elevated. Most patients recover quickly within a few hours to 1-2 days. The course of the disease is self-limiting. The resulting bacterial colonic enteritis is pseudomembranous colitis caused by Staphylococcus aureus, which has been negated by most scholars. This enteritis is caused by the exotoxin of Clostridium difficile, and Staphylococcus aureus is only a companion.
(2) toxic shock syndrome (TSS): first reported in 1978, its main clinical manifestations of high fever, shock, erythema rash, vomiting, diarrhea, and muscle pain, mucosal congestion, liver, kidney Functional damage, disorientation or altered consciousness, the pathogenesis of this syndrome is caused by the pyrogenic exotoxin C produced by Staphylococcus aureus (phage I group), but not related to the bacteria itself. TSS is more common in young women, especially in menstruation. Occlusion, but also occurs in menopausal women, men and children, although clinical manifestations can be established, but blood, vaginal, nasal, urine and other cultures still need to be carried out to observe the presence or absence of Staphylococcus aureus, and exclude other pathogen infections Possible.
(3) Staphylococcal scalded-skin syndrome (SSSS): It is generally thought to be caused by Group II phage-type Staphylococcus aureus, which produces epidermal solubilized toxins, causing diffuse erythema in newborns and young infants. And blister formation, followed by the upper part of the epidermis detached, the affected part of the inflammatory reaction is mild, only a small number of pathogenic bacteria can be found, the syndrome can be found in adults, but the rash quickly peeled, if properly treated, healed quickly, mortality low.
2. Diseases caused by direct invasion or spread of staphylococci
(1) skin, soft tissue infections: skin and soft tissue infections are mostly caused by Staphylococcus aureus, a few pathogens can be Staphylococcus aureus, mainly sputum, sputum, folliculitis, pustules, impetigo, blister Sore, otitis externa, wound infection, cavernous sinus thrombosis, mumps, acne infection, perianal abscess, etc., when the subcutaneous tissue and hair follicles are infected by Staphylococcus aureus, there may be sputum formation, common in the neck, underarm , hips and thighs, etc., recurrence is more common, sputum occurs in the back of the neck and back, is a red, swollen, painful and massive sinus drainage of the induration, folliculitis is a superficial infection of staphylococcus, sores secondary An infection caused by hair foreign body, most of which is caused by epibacteria, newborns may suffer from skin abscesses, and even severely, throughout the body, mainly pemphigus with bullae, lesions are blisters, after rupture There are pus exudation and crust formation called impetigo, otitis externa and wound (surgical or traumatic) infection are mostly caused by Staphylococcus aureus, the latter can be expressed as mild erythema, exudation of the pulp, and even honeycomb Inflammation and wounds open and drain, and cavernous sinus thrombosis Rare and serious complications of facial infection, paronychia and mumps are mainly caused by Staphylococcus aureus, while perianal abscess is especially associated with anal fistula and acne infection is mostly caused by intestinal bacteria, the pathogen is Staphylococcus aureus is only a minority.
(2) Sepsis: Staphylococcus is a common pathogen of sepsis. Among 630 cases of sepsis in Huashan Hospital affiliated to Fudan University, 258 cases (40.9%) were Staphylococcus, of which 164 cases were caused by Staphylococcus aureus and Staphylococcus aureus. 26.0%) and 94 cases (14.9%), mycobacterial sepsis occurred mostly in patients with severe primary disease or in patients with artificial organs and infants, and in the past 10 to 15 years, Staphylococcus aureus and other coagulase-negative staphylococcal septicemia The incidence rate has risen sharply in European and American countries, and its clinical manifestations are not significantly different from those caused by Staphylococcus aureus. Staphylococcal sepsis can be primary or secondary. The former only has systemic symptoms, but can not be found. Affirmative invasion route, however, most staphylococcal septicemia can find the invasion route, 40% to 50% of patients have various skin lesions before sepsis, and some patients have pneumonia, osteomyelitis, urinary tract infection, etc. It can also enter the blood circulation directly from the intravenous infusion tube. Most of the symptoms of sepsis occur within 1 week after the occurrence of the primary lesion. The onset is rapid, there are chills, high fever, gastrointestinal symptoms, joint pain, liver and spleen. Etc., with severe symptoms of toxemia, septic shock, etc., septic shock can occur early in the course of the disease, but its incidence (5% to 20%) is obviously lower than the incidence of Gram-negative septic patients The rash is seen in 30% of cases, with sputum and urticaria as the most, sometimes causing scarlet fever-like rash, the incidence of pustular rash is lower, but its presence is conducive to the diagnosis of sepsis, joint symptoms are seen in 1/5~ In 1/6 cases, most of them showed local pain and activity limitation of large joints, but there were also septic arthritis. Migration damage and/or abscess occurred in about 2/3 of the cases, according to the incidence rate. For subcutaneous soft tissue abscess, pneumonia and pleurisy, purulent meningitis, renal localized inflammation or abscess, joint abscess, liver abscess, cavernous sinus thrombosis, endocarditis, osteomyelitis (involving the spine, femur, tibia, humerus or ulna) Etc.), pericarditis, peritonitis, etc.
(3) endocarditis: can occur in the following situations: 1 normal or damaged valve can be involved in the process of staphylococcal sepsis; 2 artificial heart valve device more than 2 months after surgery, sternal wound infection, catheterization Temporary bacteremia caused by tooth extraction, etc.; 3 after pacemaker device (rare); 4 by intravenous rehydration or intravenous drug injection, endocarditis caused by Staphylococcus aureus is mostly acute. Rapid onset, chills, hyperthermia and signs of toxemia, often occur in patients with normal heart, so early in the course of the disease can be no heart murmur, and then pathological murmurs in the course of the disease, the original murmurs can have significant changes in murmur, Generally, the aortic valve is affected, while the injecting drug can affect the right heart and the tricuspid valve. The incidence of skin and mucous membrane defects is much less than that caused by the green streptococci, and the kidney, brain, fundus and other embolisms are not common. Cardiac insufficiency (about 30%) can occur early, migratory infections are more common, 50% of patients have renal suppurative infection, 40% have meningitis or brain abscess, 30% have pneumonia, lung abscess or pulmonary infarction , epiflix endocarditis can occur in Valve means after work, even also occur in heart disease, such as rheumatic heart disease, congenital heart disease, arteriosclerotic heart disease, which was mostly subacute clinical course.
(4) pneumonia: the majority of the pathogens of staphylococcus pneumonia are Staphylococcus aureus, the primary is less common, most of them are secondary to viral lung infections (measles, flu, etc.), or caused by bloodstream dissemination The patient is more common in infants and young children. Adult patients are rare. Infants with measles are often complicated by Staphylococcus aureus pneumonia. The characteristics of the disease are rapid development. The respiratory and circulatory function is good when the child is first admitted to the hospital, but it can be worse in a short period of time. The signs are not parallel with the disease. The pathogens are resistant to most antibiotics. The fever of adult patients is generally not high, but it is prolonged for many days. There may be a small amount of pus and blood stasis that is not sticky. Less, but the patient may have severe respiratory distress, and excessive ventilation, multiple inflammations and abscesses seen in the X-ray of the lungs, and formation of pulmonary bullae in the cavity. Although blood and sputum cultures are negative, they can still be combined. The clinical diagnosis is Staphylococcus aureus pneumonia. When respiratory viruses such as measles, flu and other viruses are combined with Staphylococcus aureus to cause infection, they can affect each other and the patient's condition is aggravated. Staphylococcus aureus alone does not easily invade the intact respiratory mucosa. When other pathogens such as influenza virus damaged the upper respiratory tract mucosa, or cystic fibrosis lung and bronchus by the tumor (more common in children) Yizao damage, compared with invasive S. aureus has created good conditions.
(5) Meningitis: Staphylococcal meningitis is mainly caused by Staphylococcus aureus, accounting for only 1% to 2% of various purulent meningitis. The disease is more common in children under 2 years old, but adults also account for The proportion of the disease is common in all seasons, but it is more common in July, August and September. This is related to the skin infection in summer and autumn. The clinical manifestations of staphylococcal meningitis are similar to those of other purulent meningitis, but its The onset is generally inferior to epidemic cerebrospinal meningitis; the progression of the disease is more sneak, and the cerebrospinal fluid is turbid. The total number of white blood cells in the cerebrospinal fluid can be less than 100×106/L at the beginning, so some cases can be misdiagnosed as type B when admitted to hospital. Encephalitis, tuberculous meningitis, etc., staphylococcal meningitis often occurs in the process of staphylococcal septicemia, but it can also invade the central nervous system from distant lesions through blood circulation, or directly spread from primary lesions or otitis media. And direct introduction due to skull fracture trauma, neurosurgery or diagnostic puncture, in addition to meningeal irritation of staphylococcal meningitis, rash, urticaria and other rashes, scarlet fever-like rash and body Impulsive herpes is also seen occasionally, especially the small pustular rash is the most characteristic, pustular sputum or purpura, or subcutaneous abscess, which strongly supports the possibility of the disease in the diagnosis.
(6) urinary tract infections: Staphylococcal urinary tract infections are mostly caused by Staphylococcus aureus and rot bacteria, and urinary tract infections are common in patients with indwelling catheters, especially in patients with prostatectomy, generally asymptomatic After removal of the catheter, the pathogen disappears on its own, but in a few cases, symptoms can occur and antibiotic treatment is required. Corticobacteria infection is quite common in foreign countries, usually prone to cystitis, but can also affect upper urine. The road has been isolated from the patient's kidney stones, and most strains are able to break down urea and resist neomycin.
(7) Bone and joint infection: Staphylococcus aureus can cause acute suppurative osteomyelitis, which is more common in children and men, often involving the lower end of the femur and the upper end of the humerus, followed by the spine, humerus, ankle, wrist, pelvis, humerus, etc. For blood-borne infections, it can also be secondary to trauma or septic arthritis: first from the epiphysis, after the local formation of abscess, spread to the subperiosteal or intramedullary cavity, causing subperiosteal abscess, or piercing Subcutaneous abscess is formed under the skin, about 10% of patients penetrate the joint capsule to cause septic arthritis, and chronic osteomyelitis forms the sinus. After years of healing, the periosteal hyperplasia around the lesion forms a repaired bone layer, called the capsule, which is suppuration. One of the characteristics of osteomyelitis, clinical manifestations can be seen from chills, high fever, local muscle tension, patients refuse to move the affected limbs, local bones have tenderness, skin fever, edema, bone marrow puncture culture 80% ~ 90% can detect gold Bacterial, X-ray examination, osteoporosis often occurred in the second to third weeks, after the occurrence of periosteal hyperplasia, formation of dead bone and new bone hyperplasia; scanning with radionuclide strontium and fluoride, found that the lesion is earlier than the X-ray, acute lesions Jinghe Most of the antibacterial treatment has a good prognosis. A few cases can recur in the same part to form a chronic infection. S. aureus causes suppurative spondylitis to invade the lumbar vertebrae, followed by the thoracic vertebrae and cervical vertebrae, often with low fever, back pain, and radiation to both legs. Local muscle pain, spasm, limited movement, can be complicated by paraspinal abscess, X-ray examination from 2 to 3 weeks from the beginning of the intervertebral space stenosis, bone destruction and hyperplasia, the formation of bone bridge in the intervertebral disc, for the disease X-ray The characteristics of acute staphylococcal arthritis are similar to those of acute suppurative osteomyelitis, but the joints are red, swollen, hot, and painful. The smear and culture of the joint cavity puncture can confirm the diagnosis. Patients with rheumatoid arthritis When the adrenal cortex hormone is applied for a long time, the diseased joint is easily invaded by Staphylococcus aureus, and the infection is not easily distinguished from the recurrence of rheumatoid arthritis; the smear and culture of the joint puncture fluid can help clarify the diagnosis.
(8) Foreign body implant-related infections: Coagulase-negative staphylococci account for about 50% of foreign-infected pathogens, including epiphylis, intravascular catheters, continuous abdominal perforation, body fluid shunt system, artificial valve, artificial joint , cardiac pacing electrodes, artificially shaped breasts and implanted intraocular lenses can be the cause of coagulase-negative staphylococcal infection, clinical manifestations of local or systemic infection symptoms, mostly unexplained fever, remove foreign bodies Healing can also lead to severe sepsis and death.
(9) Others: Staphylococcus can cause liver, spleen, kidney abscess, peri-renal abscess, pericarditis, empyema, etc., abscess.
Examine
Examination of staphylococcal infection
Smear or culture of blood (pus, pus, sputum, cerebrospinal fluid, feces, secretions, etc.) to find pathogens, sepsis and endocarditis are diagnosed in the corresponding clinical manifestations and positive blood culture, suspected of both in antibacterial applications The blood is taken 3 to 4 times before the culture is taken. Each time the antibiotics have been used for 1 to 2 hours, the blood must be taken 2 to 3 times per day during high fever. The blood volume can be 6 to 10 ml. The positive rate of culture in 3 to 4 times can reach 95% to 98%. This means that before the application of antibacterial drugs, if antibacterial drugs have been applied, the positive rate of culture will be reduced from over 90% to about 40%.
Negative blood culture and the detection of pathogenic bacteria from various purulent secretions (such as migratory abscess, surgical wound pus, etc.), pleural effusion, ascites and other specimens also have auxiliary diagnostic value, the discriminatory blood culture should be cautious when judging, such as More than 2 times of obtaining the same strain of Staphylococcus aureus, although it is helpful for diagnosis, the conditional laboratory should be analyzed for plasmid and restriction enzyme digestion, cerebrospinal fluid of meningitis patients, sputum of patients with pneumonia, menstruation of patients with TSS Seizures and local abscesses, vagina, etc., local secretions from patients with osteomyelitis, feces and vomit (and corresponding foods) in food poisoning patients have the opportunity to isolate pathogenic bacteria, when clinically highly suspected of gold Staphylococcal septicemia or endocarditis, and blood cultures are negative for multiple times, it can be used for serum phosphatidyl antibody detection (solid phase radioimmunoassay or enzyme-linked immunosorbent assay).
Paravertebral abscess, X-ray examination showed stenosis of the intervertebral space from 2 to 3 weeks, bone destruction and hyperplasia in the future, and the formation of a bone bridge in the intervertebral disc, which is characteristic of the X-ray of the disease.
Diagnosis
Diagnosis and identification of staphylococcal infection
diagnosis
The diagnosis of staphylococcal infection mainly depends on the clinical manifestations of infections in various parts and related smears or cultures of specimens (blood, pus, sputum, cerebrospinal fluid, feces, secretions, etc.) to find pathogens, sputum, sputum, impetigo, Mumps, folliculitis, paronychia and other skin and soft tissue infections are easy to identify, generally do not cause misdiagnosis, facial ipsies with cavernous sinus thrombosis often have ipsilateral eyeballs, indicating that pathogens have invaded the blood circulation and post-ocular tissue, need to be active Treatment.
The diagnosis of sepsis and endocarditis lies in the corresponding clinical manifestations and positive blood culture. It is suspected that the blood should be taken 3 to 4 times before the application of the antibacterial drug, and the antibiotics must be used in the interval of 1 to 2 hours. Blood is taken 2 to 3 times a day when the fever is high, and the blood volume can be 6 to 10 ml. It is best to keep blood in the blood for culture. The positive rate of 3 to 4 cultures can reach 95% to 98%. Before application, if antibacterial drugs have been applied, the culture positive rate will be reduced from over 90% to about 40%.
Negative blood culture and the detection of pathogenic bacteria from various purulent secretions (such as migratory abscess, surgical wound pus, etc.), pleural effusion, ascites and other specimens also have auxiliary diagnostic value, the discriminatory blood culture should be cautious when judging, such as More than 2 times of obtaining the same strain of Staphylococcus aureus, although it is helpful for diagnosis, the conditional laboratory should be analyzed by plasmid and restriction enzyme digestion to determine whether there is any possibility of contamination. The isolated pathogen must be in the laboratory. It is kept for a certain period of time for drug sensitivity testing.
Serum bactericidal test and pre- and post-control, diagnosis of foreign body-related infections According to the culture of foreign bodies, the foreign body must first be removed, and the bacteria on the surface of the implant can be detached by ultrasonic vibration, and then cultured; or the end of the catheter is cut 5 to 7 cm. For culture, the number of colonies 15 has diagnostic significance. For urinary tract infection of coagulase-negative staphylococci, because the bacteria grows slowly, the colony count is 102 CFU/ml, which can be regarded as bacteriuria. It should be combined with clinical infection, with bacteria or The judgment of pollution, cerebrospinal fluid from patients with meningitis, sputum from patients with pneumonia.
In patients with TSS, menstrual plugs and local abscesses, vagina, etc., local secretions of patients with osteomyelitis, feces and vomit (and corresponding foods) of food poisoning patients have the opportunity to isolate pathogenic bacteria, when clinically Highly suspected to be Staphylococcus aureus sepsis or endocarditis, and when the blood culture is negative for many times, it can be used for serum phosphatidyl antibody detection (solid phase radioimmunoassay or enzyme-linked immunosorbent assay). Specificity, usually occurs 7 to 12 days after infection. After treatment (including antibiotic treatment, pus drainage, lesion removal, etc.), the titer begins to decrease in 2 to 4 weeks, and disappears within 2 to 5 months. 90% of the culture-positive people can detect the antibodies to the phleboic acid, the false negative rate is 5% to 10%, and the false positive rate is 2% to 3%. However, 90% of the superficial S. aureus infection failed to detect phosphorus. There are two serological tests, anti--hemolysin antibody and anti-leukocid antibody detection also help to conceal the diagnosis of Staphylococcus aureus infection such as bone and joint infection, osteomyelitis, etc., but clinically It has been used sparingly and has been replaced by detection of teichoic acid antibodies.
Differential diagnosis
Gold grape infection should be differentiated from scarlet fever: the incidence of scarlet fever has decreased compared with the past, the number of patients has decreased, and the typical cases have decreased, but the atypical cases have increased. The reason is that the virulence of streptococcus itself is not very strong, and it is also penicillin. It is still sensitive and has no drug resistance, so the effect of treatment with penicillin is obvious. Some children have been infected with streptococcus. Even parents and even doctors have not diagnosed clearly. Instead, they use antibiotics, although not necessarily penicillin, other antibiotics. It also has an effect on streptococci, which is a case in which no typical manifestation of scarlet fever occurs.
Staphylococcal pneumonia should be differentiated from caseous pneumonia, Gram-negative bacilli pneumonia, lung abscess, lung cancer, further examination: X-ray, sputum culture + susceptibility test.
