Necrotizing Fasciitis

Introduction Necrotizing fasciitis is a broad and rapid soft tissue infection characterized by subcutaneous tissue and fascia necrosis, often accompanied by systemic toxic shock. The disease has been called "hospital gangrene", "acute infectious gangrene", "suppurative fasciitis", "hemolytic streptococcus gangrene" until Wilson recommended in 1952 to subcutaneous tissue shallow and deep veins Sexual gangrene is called acute necrotizing fasciitis. The disease is a mixed infection of a variety of bacteria, mainly aerobic bacteria such as Streptococcus pyogenes and Staphylococcus aureus. The infection of this disease only damages the subcutaneous tissue and fascia, and does not involve the muscle tissue of the infected site is an important feature.

Cause

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. Guiliano reported 16 cases of necrotizing fasciitis, a total of 75 kinds of bacteria were cultured, and 15 cases of at least one facultative streptococci, 10 cases of bacillus, and 8 cases of streptococcus. In Stone Martin's (1972) case, Gram-negative aerobacteria accounted for 62%, Enterococcus 19%, anaerobic streptococci 51%, and Bacteroides 24%, but no beta-hemolytic streptococcus. Although there were differences in the cases of the two groups, the results all proved that necrotizing fasciitis is often the synergistic effect of aerobic and anaerobic bacteria. The facultative bacteria first consume oxygen in the infected tissue and reduce the redox of the tissue. Potential difference (Eh), the enzyme produced by bacteria decomposes H2O2, which is beneficial to the growth and reproduction of anaerobic bacteria.

an examination

Blood routine

(1) Red blood cell count and hemoglobin measurement The inhibition of bone marrow hematopoietic function by bacterial hemolysin and other toxins has a mild to moderate decrease in red blood cells and hemoglobin in 60% to 90% of patients.

(2) The white blood cell count is leukemia-like, and the white blood cells are elevated. The counts are mostly between (20 ~ 30) × 109 / L, with the left side of the nucleus, and poisoning particles appear.

2. Serum electrolyte

Low blood calcium can occur.

3. Urine check

(1) The urine volume and urine specific gravity appear to be oliguria or urineless when the liquid supply is sufficient, and the urine specific gravity is balanced, which is helpful for judging the early damage of kidney function.

(2) urinary protein qualitative urine protein positive indicates damage to glomeruli and renal tubules.

4. Blood bacteriological examination

(1) Smear microscopy to examine the secretions and blister fluid at the edge of the lesion for smear examination.

(2) Bacterial culture The secretions and blister fluids were cultured with aerobic and anaerobic bacteria 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 bilirubin

Elevated blood bilirubin suggests red blood cell hemolysis.

7. Imaging examination

(1) X-ray film has gas in the subcutaneous tissue.

(2) CT shows small bubbles in the tissue.

8. Biopsy

Taking the fascia tissue for cryosection is also helpful for diagnosis.

Differential diagnosis

Erysipelas

Partially flaky erythema, no edema, clear boundaries, and often lymph nodes, lymphangitis. There is fever, but the systemic symptoms are relatively light and do not have the characteristic manifestations of necrotizing fasciitis.

2. Streptococcus necrosis

Infected by -hemolytic streptococcus. It is mainly caused by skin necrosis and does not involve the fascia. Early local skin redness and swelling, and then become dark red, blisters, bloody serum and bacteria. After skin necrosis, there is a dry knot, burn-like eschar.

3. Synergistic necrosis of bacteria

Mainly skin necrosis, rarely involving the fascia. The pathogenic bacteria include non-hemolytic streptococcus, Staphylococcus aureus, obligate anaerobic bacteria, Proteus and Enterobacter. The symptoms of systemic poisoning were mild, but the wounds were severely painful. The central part of the inflammation area was purple-red induration, and the surrounding area was flushed. After the central area was necrotic, ulcers formed, the skin edge sneaked, and there were scattered small ulcers around.

Clostridium muscle necrosis

It is an infection of obligate anaerobic bacteria, which often occurs under the conditions of war wounds, wounds and wounds. Early local skin is bright, tense, squeaky, and lesions can affect deep muscles. Gram-positive crude bacilli can be detected from the secretion smear. Muscle contamination and necrosis can occur with myoglobinuria. X-ray films can be found to have free gas between the muscles.

5. Clostridium perfringens

This disease is caused by anaerobic streptococcus or a variety of anaerobic bacteria, which 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 is a localized gas in the inflammatory tissue.

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