Septicemia

Introduction to sepsis Septicemia refers to the acute systemic infection caused by the growth and reproduction of pathogenic bacteria in the blood circulation. The clinical symptoms are chills, fever, rash, joint pain and hepatosplenomegaly. Some patients may also have irritability, cold extremities and Purpura, fine pulse, rapid breathing, blood pressure, etc. The mortality rate can reach 30-50%, especially in the elderly, children, those with chronic diseases or immunocompromised, those who are not treated promptly and have complications, and the prognosis is even worse. basic knowledge Sickness ratio: 0.0001% Susceptible people: no specific people Mode of infection: non-infectious Complications: septic shock liver abscess jaundice

Cause of sepsis

Infection (35%):

Pathogens and common septic pathogens: All kinds of bacteria with pathogenicity or conditional pathogenicity can become the pathogen of sepsis. Due to different ages, patients have different underlying diseases, afferent pathways and age groups. The effects of different factors, the bacteria causing sepsis are also different. Before 1950, the pathogens of sepsis were mainly hemolytic streptococcus and pneumococcus, accounting for more than 50% of the total, and staphylococci (Golden Portuguese + Portuguese) accounted for 20%. Gram-negative bacilli account for about 12%. With the wide application of broad-spectrum antibiotics, corticosteroids and immunosuppressants, the pathogen spectrum of sepsis has also changed. Because hemolytic streptococcus and pneumococci are highly sensitive to penicillin, as sepsis The pathogen is now rare.

It is generally believed that Gram-negative bacilli is dominant after the 1960s, and Staphylococcus is susceptible to drug resistance, so it is still one of the main pathogens of sepsis. Gram-positive cocci sepsis has an upward trend since the 1980s. Statistics from the US Centers for Disease Control and Prevention The proportion of Gram-positive cocci sepsis was 37% in 1984 and 55% in 1986-1989. Domestic data showed that Gram-negative bacilli were mostly septic, up to 63% to 68%, and Gram-positive cocci sepsis The proportion increased, anaerobic bacteria and fungal sepsis also increased, Gram-negative pathogenic bacteria, in addition to E. coli, common are also Klebsiella, Pseudomonas aeruginosa, Aerogen, Proteus, etc.; Fungi are Candida albicans More common, Aspergillus and Cryptococcus can also be seen.

In recent years, anaerobic bacteria accounted for 8% to 26% of the pathogens of sepsis (more hospitals can not do anaerobic bacteria detection), mainly Bacteroides fragilis and Streptococcus pneumoniae, and can also be significantly lower in the body's defense function. Multiple bacterial sepsis occurs, that is, two or more pathogenic bacteria are detected in the same specimen, or multiple pathogenic bacteria are cultured from several blood or bone marrow specimens within 72 hours. Generally, multiple bacterial sepsis accounts for about the total number of sepsis. 10%.

Bacterial toxins (25%):

Regarding bacterial toxins, Gram-positive cocci can produce both inner and outer toxins, and recent studies have shown that:

1 Staphylococcal endotoxin TSST1 (toxic shock syndrome toxin 1) can stimulate the body's monocytes to release IL-1 and TNF.

2 If TSST-1 binds to the streptococcal exotoxin (erythrotoxin) to form a superantigen, the antigen can adsorb on the type II histocompatibility molecule to form a complex, and then bind to the VB part of the T cell antigen receptor. Produces a large number of cytokines.

3 Many toxins produce arachidonic acid metabolites through the lipoxygenase or cyclooxygenase pathways.

4 Staphylococcal a-toxin causes platelets to release PF4, PF5, activates the endogenous coagulation system, and induces DIC.

5 In addition to stimulating the body to produce the above-mentioned inflammation meson, it can directly damage the vascular endothelial cells of the organs, forming many micropores, causing some transmembrane ions (Ca2) and small molecules to overflow, ion imbalance, and can also cause organ dysfunction. .

About the role of cell wall components (15%):

The main pathogenic component of the cell wall of Gram-positive bacteria is the phospho-wall acid of peptidoglycan, which can selectively activate the complement system, release arachidonic acid metabolites and produce cytokines.

1 In the presence of protein A, the peptidoglycan of pneumococci can cause platelet aggregation and induce DIC.

2 The peptidoglycan precursor isolated from penicillin-treated Streptococcus faecalis and the lipoteic acid of Staphylococcus can stimulate the release of IL-1 and TNF by monocytes. The pathological changes of sepsis may be due to the pathogen type. The length of the disease and the underlying diseases vary. The changes of various organs and tissues caused by early pathogenic toxins are mainly inflammatory reactions, with turbid swelling, focal necrosis and steatosis. When the monocytic phagocytic system proliferates actively. The liver and spleen are swollen. As the disease course prolongs, the more persistent lesions such as edema, capillary damage and skin rash, skin, lung, liver, kidney and brain may appear small edema. Water in the joint cavity, purulent meningitis, pleural inflammation, etc.

The pathogen can pass through the damaged skin, the mucous membrane invades the body, and can also be released from the latent lesions, enter the blood circulation through the lymphatic vessels or veins and multiply in it. At this time, the body's defense mechanism is activated, in the antibody and complement. Under the conditioning effect, the pathogen is effectively eliminated by the mononuclear macrophage system, which becomes a transient bacteremia. If the patient has poor conditions (age, basic condition, current condition, immune function, etc.), the number of pathogens is large. When the virulence is strong, the above normal reaction process will not proceed smoothly, and the body will produce a inflammatory reaction syndrome. A series of chain reaction processes can lead to multiple organ dysfunction and failure in the clinic. Can the bacteria enter the human body? The formation of infection status and the invasive blood circulation can develop into sepsis, and the number of invading bacteria and/or its virulence, the human defense function and the immune response are closely related to many factors.

Septicemia prevention

For high-risk patients who are prone to sepsis, they should closely observe the changes of the disease. In the event of signs of sepsis or suspected conditions, they should actively check for decisive treatment. For skin infections such as sputum and sputum, squeezing treatment should be avoided, and various catheters in the body should be infected. Need to be removed in time, burn patients and patients with blood diseases should be strictly isolated when receiving chemotherapy or bone marrow transplantation; wards in patients with infectious wards who have lived or have lived with sepsis should strengthen disinfection and isolation measures to prevent drug-resistant Staphylococcus aureus, P. aeruginosa Bacteria and fungi spread.

Septicemia complications Complications , septic shock, liver abscess, jaundice

Staphylococcus aureus can be complicated by septic shock, kidney, liver abscess, Gram-negative bacilli sepsis can be complicated with heart failure; jaundice, liver failure; acute renal failure, respiratory distress and DIC, etc., can produce bacillus Severe hemolytic anemia and renal failure can also be complicated by endocarditis and meningitis.

Symptoms of sepsis Common symptoms Persistent relaxation, heat, cold, meningitis, lower extremity, wet gangrene, ascites, rash, purulent discharge, skin and soft tissue infection, sepsis, fever

Septicemia itself has no special clinical manifestations. The manifestations seen in sepsis can also be seen in other acute infections, such as recurrent chills and even chills. Hyperthermia can be either relaxation or intermittent, with rash-based rashes. Joint pain involving large joints, mild liver and spleen, severe changes may be caused by consciousness, myocarditis, septic shock, DIC, respiratory distress syndrome, etc., sepsis caused by various pathogenic bacteria, and different Clinical features.

1. Staphylococcus aureus sepsis: the primary lesion is often skin sputum or wound infection, a few patients with poor body resistance in hospital infection, the blood bacteria are mostly from the respiratory tract, the clinical onset is acute, and its rash is a defect , urticaria, pustular rash and scarlet fever-like rash and other forms, the occurrence of defects on the conjunctiva is of great significance, joint symptoms are more obvious, sometimes red and swollen, but purulent is rare, migratory damage can occur in about 2 / 3 patients, The most common are multiple pulmonary infiltration, abscess and pleurisy, followed by purulent meningitis, renal abscess, liver abscess, endocarditis, osteomyelitis and subcutaneous abscess, septic shock is less common.

2. S. septicemia: more common in hospital infections, when patients receive broad-spectrum antibiotic treatment, the bacteria easily form resistant strains (with methicillin-resistant strains), the number of bacteria in the respiratory tract and intestines increased significantly, Causes systemic infections, also commonly seen after interventional treatment, such as artificial joints, prosthetic valves, pacemakers and various catheter indwelling.

3. Enterococcus septicemia: Enterococcus is an opportunistic infection, usually parasitic in the intestines and urinary system, its incidence has increased in the past 30 years, accounting for about 10% of sepsis in hospital infections in the United States, in the United States It has also risen to the fourth place, with clinical manifestations of urinary tract infections and endocarditis being the most common, as well as meningitis, osteomyelitis, pneumonia, enteritis and skin and soft tissue infections.

4. Gram-negative bacilli sepsis: Different pathogens enter the blood through different routes, which can cause complex and diversified manifestations. Sometimes these manifestations are concealed by the symptoms and signs of the primary disease, and the pre-existing health status is poor, most of which are accompanied by influence. The primary disease of the body's defense function belongs to the hospital with more infections, chills, high fever, sweating, and the double-peak heat type is more common. Occasionally, it is a three-peak heat type. This phenomenon is caused by other pathogens. Rare, worthy of attention, Escherichia coli, Alcaligenes and other septicemia can also appear like typhoid fever, accompanied by relative pulsation, a small number of patients may have body temperature does not rise, rash, joint pain and migratory lesions than Gram There is less positive septicemia, but the clinical manifestations of Pseudomonas aeruginosa secondary to malignant tumors are more dangerous. The rash can be present and heart necrotizing. About 40% of patients with Gram-negative bacilli can develop septic shock and have low protein. Patients with blood are more likely to occur, severe cases may have multiple organ damage, manifested as arrhythmia, heart failure; jaundice, liver failure; acute renal failure, respiratory distress With DIC and so on.

5. Anaerobic septicemia: 80% to 90% of its pathogenic bacteria are Bacteroides fragilis, in addition to anaerobic streptococci, digestive cocci and Clostridium perfringens, etc., the invasion route is in the gastrointestinal tract and female reproductive tract Mainly, hemorrhoids, ulcers, and clinical manifestations are similar to aerobic septicemia. The characteristic manifestations are:

1 The incidence of jaundice is as high as 10% to 40%, which may be related to the endotoxin of Bacteroides directly acting on the toxin-induced hemolysis of the liver and Clostridium perfringens;

2 local lesion secretions have a special stinky smell,

3 easy to cause septic thrombophlebitis and thoracic cavity, lung, endocardium, abdominal cavity, liver, brain and bone joints, etc., this is more common in fragile Bacteroides and anaerobic streptococcus sepsis,

4 In the production of capsular bacillus sepsis, severe hemolytic anemia and renal failure may occur, and gas is formed in local migratory lesions. Anaerobic bacteria often together with aerobic bacteria cause multiple bacterial sepsis, and the prognosis is dangerous.

6. Fungal sepsis: generally occurs in the late stage of a serious primary disease, often in patients with liver disease, kidney disease, diabetes, blood disease or malignant tumors or patients with severe burns, heart surgery, organ transplants, they have more Long-term application of broad-spectrum antibiotics, adrenocortical hormones and/or anti-tumor drugs, so almost all patients suffering from this disease are low body defense function, and the incidence has increased in recent years, the clinical manifestations of fungal sepsis The performance is almost the same as other sepsis, and most of them are accompanied by bacterial infections. Therefore, the symptoms of toxemia are often concealed by the simultaneous bacterial infection or primary disease, and it is difficult to make a clear diagnosis at an early stage. Therefore, when the above-mentioned patients suffer from the infection, After applying a sufficient amount of suitable antibiotics, it is necessary to consider the possibility of fungal infections. To do blood, urine, throat swabs and cockroaches, you can also do direct smear to check for fungal bacteria. Silk and spores, if the same fungal result is obtained in multiple or multiple samples, the pathogen can be clear, and the lesion can be tired. Heart, lung, liver, spleen, brain and other organs and tissues, the formation of multiple small abscesses, can also be complicated by endocarditis, meningitis and so on.

Septicemia check

Blood tests, especially white blood cell counts and classification tests, may indicate the degree of bacterial infection, but obtaining positive pathogens is essential for diagnosis and treatment. To improve the positive rate of pathogen culture, it is necessary to pay attention to the specimens in time. Fortunately, before the administration of antibiotics; to be repeated; to collect specimens (such as blood, urine, stool, bone marrow, sputum, secretions, etc.) in multiple parts; the amount of specimens to be inspected should not be too small (such as blood specimens for inspection) The blood volume should be at least 1/10 of the medium, that is, 5 to 10 ml). In combination with clinical characteristics, multiple suspected bacteria should be cultured at the same time (general bacteria, anaerobic bacteria, L-type bacteria, fungi, etc.) at the same time. After the isolation of the pathogen, the susceptibility test should be done. In the specific method of laboratory operation, it has been improved in recent years. In addition to the original culture method, it can also be used:

1 isotope culture instrument, gas phase spectrometer, Malthus culture instrument and other special instruments for blood culture, can early indicate whether there is bacterial growth;

2 blood microporous membrane collection method, can remove antibiotics in serum, and facilitate bacterial growth;

3 lysis centrifugal blood culture method is conducive to the detection of yeast;

4 The gene amplification method (PCR) using molecular biology technology is more rapid, sensitive and specific in detecting pathogenic microorganisms. Now there are kits for detecting Escherichia coli, Mycobacterium tuberculosis, Staphylococcus aureus and fungi. For clinical use;

5 blood lysate test (LLT), used to detect blood, urine and pleural and ascites samples such as endotoxin to confirm whether it is Gram-negative infection;

6 immunofluorescence and ELISA antigen detection;

7 Indium labeled immunoglobulin detection.

In the case of enterococci sepsis, the lungs are infiltrated with shadows on the X-ray.

Septicemia diagnosis

Diagnostic criteria

Diagnostic basis: Because most cases of sepsis are secondary to various infections and lack of specific clinical manifestations, it is easy to cause missed diagnosis or misdiagnosis. In order to improve the early diagnosis rate of sepsis, it is necessary to first improve the vigilance against sepsis and promptly carry out suspicious cases. Corresponding examination, therefore, there is fever, total white blood cell count and neutrophil elevation, recent respiratory, digestive tract, urinary tract infection or burn, history of device operation and various focal infections have not been effectively treated by antibacterial therapy The controller should be highly suspected of the possibility of sepsis. The blood culture bacteria positive is the most reliable diagnosis basis for sepsis. If the blood culture is negative and the bone marrow culture is positive, the meaning is the same as the blood culture positive, other such as sputum, urine, pleural effusion, The culture of ascites, purulent secretions, etc. has reference significance for definite diagnosis. LLT can be used to detect the presence or absence of endotoxin in blood, urine, chest and ascites samples to confirm whether it is Gram-negative infection, according to reports at home and abroad. Only half of the LLTs in the plasma of patients with Gram-negative coccidia have been shown to be positive, ie positive to support diagnosis, Not exclude the diagnosis of, if blood culture negative, occurs in the course of the conjunctiva, oral mucosa, etc. petechial rash, hepatosplenomegaly, migratory abscess or damage, the diagnosis of sepsis may be substantially established.

Differential diagnosis

The disease should be differentiated from typhoid, miliary tuberculosis, allergic subsepsis, rheumatism, lupus erythematosus, certain viral infections, brucellosis, lymphoma, malignant histiocytosis.

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