acute cellulitis
Introduction
Introduction to acute cellulitis Acute cellulitis is an acute, diffuse, suppurative infection of subcutaneous, subfascial, intermuscular or deep loose connective tissue. Common pathogens are hemolytic streptococcus and Staphylococcus aureus, and a few are anaerobic and Escherichia coli. cause. In recent years, with the development of microbiology and the improvement of detection methods, anaerobic infections and mixed infections have received extensive attention. Many studies have shown that anaerobic infections and mixed infections have a significant increasing trend. Cellulitis caused by Gram-negative bacteria is less common. The characteristics of this disease are: any part of the skin can be infected, and the lesion is not easy to be limited, rapid spread, no obvious boundary between the diseased tissue and normal tissue, the symptoms of systemic poisoning are obvious, so the treatment of local infection requires active application of antibiotics, early adoption Anti-shock measures. basic knowledge The proportion of illness: 0.95% Susceptible people: no specific population Mode of infection: non-infectious Complications: shock, jaundice, sepsis
Cause
Causes of acute cellulitis
Trauma factors (35%):
The disease is mostly caused by skin and mucous membrane damage. The loose connective tissue under the skin is caused by pathogenic bacteria infection, and can also be directly spread by local suppurative infection or through lymphatic and blood transmission.
Anaerobic infection (35%):
Most of the pathogens are hemolytic streptococcus or Staphylococcus aureus, but also anaerobic bacteria, E. coli infection or mixed infection. In immunodeficient patients, occasionally cellulitis caused by Gram-negative bacteria.
Pathogenesis
The types of pathogenic bacteria are different, and the main pathological changes are also different.
Acute cellulitis caused by hemolytic streptococcus, due to the action of streptokinase and hyaluronidase, the lesion spreads rapidly, the pus is thin, bloody, prone to sepsis, acute cellulitis caused by Staphylococcus aureus is easily restricted and forms an abscess. The pus is thicker and is caused by gas-producing bacteria such as Escherichia coli, anaerobic bacilli, and anaerobic streptococci. It can be emphysema in the lesion, which is called bursting cellulitis.
Local changes in cellulitis are mainly congestion, swelling, inflammatory cell infiltration, normal tissue structure destruction, tissue necrosis in the central area of the lesion, abscess formation after liquefaction, may also be accompanied by peripheral lymphangitis, lymphadenitis, accompanied by anaerobic The pathological necrosis of the infected tissue is more serious, the expansion speed is faster, and there is often obvious deep tissue destruction. The mechanism is: First, the anaerobic bacteria are often mixed infection, and the short-chain fatty acids produced by the Bacteroides in the lesion can be inhibited. The neutrophil's lethality, under the condition of increased extracellular fluid acidity, fatty acids can mediate the penetration of hydrogen ions into the cells, so that the intracellular fluid is acidified, thereby impairing cell function; under acidic conditions, some antibiotics can not play Some effects, followed by cellulose deposition in the infected area, affect the removal of bacteria, so the pathology associated with anaerobic infection is particularly serious.
Prevention
Acute cellulitis prevention
Prevention of this disease should pay attention to the skin's cleanliness and avoiding damage on a regular basis; it should be treated as soon as possible after skin injury, and some kind of suppurative disease should be treated promptly. Infants and the elderly have weak anti-infective ability and should pay attention to life care.
1. Timely treatment of various localized bruises to reduce the incidence of this disease.
2. The affected part should be raised to facilitate the absorption of inflammation.
3. Do not eat spicy spicy food, those who are hot must rest in bed.
Complication
Acute cellulitis complications Complications, shock, jaundice, sepsis
1. Toxic shock: systemic inflammatory response syndrome can occur, manifested as high fever or hypothermia, heart rate > 90 beats / min, shortness of breath or hyperventilation, PaCO2 <4.3kPa, white blood cell count > 12 × 109 / L or < 4 × 109 / L, or immature white blood cells > 0.1% and so on.
2. Sepsis: sudden chills, followed by high fever up to 40 ~ 41 ° C, or low temperature, abnormal mind, pulse speed, liver and spleen can be swollen, severe cases of jaundice or subcutaneous bleeding.
Symptom
Acute cellulitis symptoms common symptoms high heat fatigue skin necrosis dyspnea chills convulsions throat edema
1. Local symptoms: local red, swollen, hot, painful lesions, and rapidly expand to the surrounding, red and swollen skin and surrounding normal tissue without obvious boundaries, the central part of the color is darker, the surrounding color is lighter, the infected part is shallow, tissue The more slender, the swelling is obvious and diffuse, the pain is lighter; when the infection is deep or the tissue is dense, the swelling is not obvious, but the pain is severe.
2. Systemic symptoms: patients with varying degrees of systemic symptoms, such as chills, fever, headache, fatigue and increased white blood cells, etc., generally deep cellulitis, anaerobic bacteria and gas-producing bacteria caused by burst cellulitis The systemic symptoms are more obvious. There may be severe symptoms such as chills, high fever, convulsions, convulsions, acute cellulitis of the mouth, submandibular and neck. Throat edema and compression of the trachea may occur, causing difficulty in breathing and even suffocation. Sometimes inflammation can spread to the mediastinum, causing mediastinal inflammation and mediastinal abscess.
3. Signs: local redness and swelling of the lesions, obvious tenderness, localized redness and swelling of the deeper lesions are not obvious, often only local edema and deep tenderness, pronounced cellulitis often occurs in the perineum, abdominal wounds, when examining Check the pronunciation; loose connective tissue and fascia necrosis, severe edema accompanied by progressive skin necrosis, pus smelly.
Examine
Acute cellulitis examination
Peripheral blood
(1) White blood cell count: When the infection is normal, the white blood cell count is increased by >10×109/L, if the white blood cell count is >(20-30)×109/L, or <4×109/L, or immature white blood cells>0.1%. , or when toxic particles appear, should be alert to septic shock and sepsis.
(2) Leukocyte differential count: elevated white blood cell count is often accompanied by elevated neutrophils.
2. Diabetes related examination
(1) Fasting plasma glucose measurement: Both fasting blood glucose levels are measured twice, and the possibility of diabetes should be considered.
(2) Glycosylated serum protein: This test is not affected by clinical blood glucose fluctuations, and higher than normal to help diagnose diabetes.
(3) Glycated hemoglobin: Glycated hemoglobin is positively correlated with blood glucose concentration and is irreversible, and diabetes is often 2 to 3 times higher than normal.
3. Bacteriological examination
(1) Bacterial culture: For multiple infections and repeated infections, the pus can be directly extracted from the abscess for bacterial culture, and the positive result is helpful for the diagnosis of sputum.
(2) Drug sensitivity test: While the pus bacterial culture, the drug sensitivity test can provide a scientific basis for clinical drug treatment.
4. Imaging examination
It helps to judge early disease and understand the degree of local tissue damage.
(1) B-mode ultrasound: the local tissue structure of the lesion is disordered, the central part is uneven and the middle and low echoes, the surrounding tissue edema is obvious, and the boundary is unclear.
(2) X-ray film: the bottom of the mouth, submandibular, neck cellulitis spread caused by mediastinal abscess, visible high density image of mediastinal widening.
(3) CT: edema around the tissue, liquefaction in the center, paroxysmal cellulitis can be seen in different degrees of subcutaneous gas and deep soft tissue emphysema, mediastinal abscess, visible high density image of mediastinal widening.
5. Arterial blood gas and pH
Helps to understand the body's metabolic status and timely find acid-base imbalance.
Diagnosis
Diagnosis and diagnosis of acute cellulitis
Diagnostic points
1. Clinical manifestations and signs: Diagnosis can be made based on typical local and systemic manifestations and signs.
2. Laboratory examination: elevated white blood cell count, cytological examination of pus is helpful for diagnosis.
3. Imaging examination: It is helpful for the degree of infection and judgment of pathogens.
Differential diagnosis
1. erysipelas: infection caused by hemolytic streptococcus invading the skin and reticular lymphatic vessels, localized as reddish plaques, fading after finger pressure, mild edema of the skin, slightly elevated edges, clear boundaries, rapid spread of infection, but not Suppuration, rarely tissue necrosis, easy recurrent, repeated limbs of the author, may have subcutaneous lymphatic obstruction.
2. Necrotizing fasciitis: often a mixed infection of aerobic and anaerobic bacteria, acute onset, severe systemic symptoms, local symptoms are not obvious, infection spreads rapidly along the fascia, necrosis of the fascia and subcutaneous tissue, patients often There are anemia, toxic shock, visible skin ulcers, thin pus, pus culture can have a variety of bacteria growth.
3. Gas gangrene: gas-producing cellulitis should be differentiated from gas gangrene, which is heavier before the disease, often deep and muscle, with injured limbs or physical dysfunction; wound secretions have some astringency, Pus smear examination can roughly distinguish the pathogen morphology.
