Necrotizing Fasciitis
Introduction
Introduction to necrotizing fasciitis Necrotizing fasciitis is a rare and serious soft tissue infection that is different from streptococcal necrosis and is often a mixed infection of many bacteria. Rea and Wyrick confirmed that pathogens include Gram-positive hemolytic streptococcus, Staphylococcus aureus, Gram-negative bacteria and anaerobic bacteria. In the past, anaerobic bacteria were often not found due to the backward anaerobic culture technology. However, in recent years, it has been confirmed that anaerobic bacteria such as Bacteroides and Streptococcus pneumoniae and cocci are often one of the pathogens of this disease, but few are simply anaerobic. Bacterial infection. According to the condition, necrotizing fasciitis can be divided into two types: one is the spread of pathogenic bacteria through trauma or primary lesions, which causes the condition to suddenly deteriorate and the soft tissue to rapidly necrosis. Another disease develops slowly, mainly with cellulitis, multiple ulcers on the skin, pus smear, dishwashing water, extensive sneak around the ulcer, and sputum sound, local numbness or pain These characteristics are not common to all cellulitis. Patients often have obvious toxemia, chills, high fever and low blood pressure. Hypocalcemia can occur when the subcutaneous tissue is extensively necrotic. Bacteriological examinations are of particular importance for diagnosis, especially smear examination of wound pus. The key to the treatment of necrotizing fasciitis is early and extensive expansion surgery, fully cutting the sneak skin, removing necrotic tissue, including necrotic subcutaneous fat tissue or superficial fascia, but the skin can usually be retained. The wound was opened, rinsed with 3% hydrogen peroxide or 1:5000 potassium permanganate solution, loosely packed with gauze, or inserted with a polyethylene catheter for lavage after surgery. Baxter recommends flushing with saline containing neomycin 100 mg/L and polymyxin B 100 mg/L. It is also recommended to wash with carbenicillin or 0.5% metronidazole solution. The logistical dressing changes accelerate the shedding of necrotic tissue, and it is found that necrotic tissue needs to be expanded again. Bacterial culture should be repeated during dressing to detect secondary bacteria such as Pseudomonas aeruginosa, Serratia marcescens or Candida early. basic knowledge The proportion of sickness: 0.004% - 0.005% Susceptible people: no specific population Mode of infection: non-infectious Complications: anemia, diffuse intravascular coagulation, shock
Cause
Causes of necrotizing fasciitis
(1) Causes of the disease
Necrotizing fasciitis is often a mixed infection of a variety of bacteria, including Gram-positive hemolytic streptococcus, Staphylococcus aureus, Gram-negative bacteria and anaerobic bacteria, with the development of anaerobic culture technology, confirmed anaerobic Bacteria are an important pathogen, and necrotizing fasciitis is often the result of a synergistic effect of aerobic and anaerobic bacteria.
Necrotizing fasciitis is often accompanied by immune damage to the whole body and local tissues, such as secondary skin abrasions such as abrasions, contusions, insect bites, etc. After the operation of the hollow organ, the drainage of the perianal abscess, extraction, and abdominal cavity After the operation of the mirror, even after the injection (most after the injection of drugs) can occur, long-term use of corticosteroids and immunosuppressants to develop this disease, some patients with necrotizing fasciitis combined with diabetes, atherosclerotic cardiovascular disease , obesity, malnutrition, kidney disease, shock, metastatic tumors, multiple myeloma and other diseases.
(two) pathogenesis
A variety of bacteria invade the subcutaneous tissue and fascia. The aerobic bacteria first consume the oxygen in the infected tissue, which reduces the oxidation-reduction potential difference (Eh) of the tissue. At the same time, the enzyme produced by the bacteria decomposes the H2O2 in the tissue, thus creating less The oxygen environment is conducive to the breeding and reproduction of anaerobic bacteria.
Bacterial infection spreads rapidly and extensively along the fascia tissue, causing extensive inflammation of the infected tissue, edema, followed by inflammatory embolism of the skin and subcutaneous small vascular network, tissue dystrophies, resulting in ischemic tunnel-like necrosis of the skin. Even ring necrosis occurred. Microscopic examination revealed obvious inflammatory manifestations in the vessel wall. Neutrophil infiltration occurred in the deep dermis and fascia. Fibrous embolism was observed in the fascia, and fibrinous necrosis occurred in the venous and venous walls. Gram staining can detect pathogenic bacteria in the damaged fascia and dermis without any damage to the muscles.
Prevention
Necrotizing fasciitis prevention
Improve the body's immunity, actively treat primary systemic diseases and local skin damage, long-term use of corticosteroids and immunosuppressive agents should pay attention to strengthen systemic nutrition, prevent the occurrence of trauma, skin contaminants should promptly remove pollutants, disinfection wounds When you have a general discomfort, you should actively seek help from your doctor.
Complication
Necrotic fasciitis complications Complications, anemia, diffuse intravascular coagulation shock
1. Anemia.
2. Diffuse intravascular coagulation.
3. Toxic shock.
4. Multiple organ failure.
Symptom
Necrotizing fasciitis symptoms Common symptoms Severe pain conscious disorder Shallow fasciitis Anorexia chills Low blood pressure High heat Foot burning jaundice Dehydration
This disease mainly occurs after skin trauma or surgery, such as skin abrasions, surgical incisions, hemorrhoids, perianal fistula or diabetic foot ulcers, and more common in diabetes, cardiovascular and renal diseases, the performance can be acute A fulminant or chronic intractable latent disease. Clinically, this type of subcutaneous fascia is irritating and has many different names. It is briefly described as follows:
(1) hemolytic streptococcus gangrene
It is an acute severe suppurative disease caused by hemolytic streptococcus. Some people think it is a gangrenous erysipelas. More often after a trauma or bruise, the outbreak occurs in a clear, painful red swelling. It occurs mostly in the extremities, and the skin lesions rapidly expand within 1 to 3 days, accompanied by severe systemic symptoms such as high fever and exhaustion. Within 2 to 3 days of onset, the affected part is dark red, most of the blisters or bullae occur on it, and irregular hemorrhagic necrosis occurs in the lower part. After the blisters are broken, the skin has a clear skin gangrene and is constantly expanding. The skin is numb, with necrotic black eschar, surrounded by redness, so it is like a third degree burn. After 1 week or 10 days, necrotic tissue can be spoiled and shed, but metastatic lesions can occur in other parts of the body. Most patients develop their condition, the symptoms of poisoning gradually increase, and they die due to sepsis or shock.
(B) Clostridium anaerobic cellulitis
It is a serious skin tissue necrosis caused by Clostridium, and it has a wide range of gas formation. It is easy to occur in areas where the contamination or trauma is incompletely debrided, especially in the perianal, abdominal wall, buttocks and lower limbs. A site contaminated by feces. Its clinical manifestations are similar to those of necrotizing fasciitis, but there are some hypoxic gangrene. Its secretions are black and stinking, often contain fat droplets, and there are obvious sputum sounds around the lesions. X-ray examination of soft tissue There is a lot of gas in it.
(C) non-C. difficile anaerobic cellulitis
Symptoms are similar to Clostridium anaerobic cellulitis, and are basically necrotizing fasciitis, but mainly infections of mixed anaerobic flora.
(4) Synergistic necrotizing cellulitis
It is a variant of necrotizing fasciitis with symptoms of systemic poisoning and bacteremia. Occurred in diabetes, obesity, old age and heart and kidney disease, the lesions are more likely to occur in the lower limbs and near the perianal, often can die.
(5) Fornier gangrene
It is a serious gangrene that occurs in the male penis, scrotum, perineum and abdominal wall. More common in patients with diabetes, local trauma, incarcerated phimosis, urethral fistula or genital surgery. The skin necrosis is caused by the damage of the perianal fasciitis affecting the blood supply to the skin. The clinical manifestation is acute onset, sudden onset of redness on the skin, and soon develop into a dark red plaque or ulcer. The edge of the ulcer is Sneak, the surface has serous exudation, intense tenderness, often accompanied by fever. A large number of Gram-positive bacteria, Enterobacter and anaerobic bacteria can be detected at the lesion.
Examine
Examination of necrotizing fasciitis
Blood routine
(1) Red blood cell count and hemoglobin determination: The inhibition of bone marrow hematopoietic function by bacterial hemolytic toxins and other toxins has a mild to moderate decrease in red blood cells and hemoglobin in 60% to 90% of patients.
(2) White blood cell count: Leukemia-like reaction, white blood cells rise, the count is mostly between (20 ~ 30) × 109 / L, there is a nuclear left shift, and poisoning particles appear.
2. Serum electrolyte
Low blood calcium can occur.
3. Urine check
(1) Urine volume, urine specific gravity: When there is sufficient liquid supply, oliguria or no urine, urine specific gravity, etc., help to judge the early damage of kidney function.
(2) urinary protein characterization: urinary protein positive indicates damage to glomeruli and renal tubules.
4. Blood bacteriological examination
(1) Smear microscopy: take the secretions and blister fluid on the edge of the lesion and do a smear examination.
(2) Bacterial culture: Aspirate and blister fluids were taken for aerobic and anaerobic cultures respectively. No Clostridium was found to contribute to the judgment of this disease.
5. Serum antibodies
There are antibodies induced by streptococcus in the blood (the hyaluronidase released by streptococci and deoxyribonuclease B can induce the production of antibodies with high titers), which is helpful for diagnosis.
6. Serum electrolyte
May have low blood calcium.
7. Serum bilirubin
Elevated blood bilirubin suggests red blood cell hemolysis.
8. Imaging examination
(1) X-ray film: There is gas in the subcutaneous tissue.
(2) CT: Shows the small bubbles in the organization.
9. Biopsy
Taking the fascia tissue for cryosection is also helpful for diagnosis.
Diagnosis
Diagnosis and differentiation of necrotizing fasciitis
Diagnostic criteria
Fisher proposed six diagnostic criteria with certain reference value:
1. Extensive necrosis of subcutaneous superficial fascia with extensive sneak tunnels spreading into surrounding tissues.
2. Moderate to severe symptoms of systemic poisoning with altered consciousness.
3. Did not involve the muscles.
4. Wound, blood culture did not find Clostridium.
5. No significant vascular obstruction.
6. Debridement tissue examination: extensive leukocyte infiltration, fascia and adjacent tissue focal necrosis and microvascular embolization were found.
Bacteriological examination is of great significance for diagnosis. The culture material is best collected from the edge of progressive lesions and blister fluid, smear examination, and aerobic and anaerobic culture respectively, to determine the presence or absence of streptococcus in the blood. The antibodies (the hyaluronidase and deoxyribonuclease B released by Streptococcus can produce highly titrated antibodies) are useful for diagnosis.
Differential diagnosis
Erysipelas
Partially flaky erythema, no edema, clear boundary, and often lymph nodes, lymphangitis, fever, but the systemic symptoms are relatively light, does not have the characteristic manifestations of necrotizing fasciitis.
2. Streptococcus necrosis
Infected by -hemolytic streptococcus, mainly skin necrosis, does not involve the fascia, early local skin redness, and then becomes dark red, blisters, bloody bacteria and bacteria, dry knot after skin necrosis, similar to burns Anxious.
3. Synergistic necrosis of bacteria
Mainly skin necrosis, rarely involving the fascia, pathogenic bacteria are non-hemolytic streptococcus, Staphylococcus aureus, obligate anaerobic bacteria, Proteus and Enterobacter, etc., patients with mild symptoms of systemic poisoning, but the wound pain is severe, inflammation The center of the area is purple-red induration, surrounded by flushing, and the central area is necrotic and forms an ulcer. The skin edge sneaked and there were scattered small ulcers around.
Clostridium muscle necrosis
It is an obligate anaerobic infection. It often occurs under the conditions of war wounds, wounds and wounds. Early local skin is bright, nervous, and has sputum pronunciation. The lesions can affect the deep muscles. The secretion smears can detect Gram-positive. Large bacilli, muscle contamination and necrosis, may have myoglobinuria, X-ray film can be found free air between muscles.
5. Clostridium perfringens
The disease is caused by anaerobic streptococci or a variety of anaerobic bacteria. It is rare, the cause is similar to that of gas gangrene, but the condition is mild, there is serous pus in the wound, and there are localized gases in the inflammatory tissue.
