Necrotizing infections (NIs) of the skin and soft tissue are caused by various microorganisms and often have a polymicrobial etiology. The main nosological forms are represented by necrotizing fasciitis, bacterial and streptococcal gangrene. Necrotizing infections of clostridial etiology are rare, other pathogens are more common. Most cases of necrotic infections, which manifest as necrotizing fasciitis, are caused by the combination of group A β-hemolytic streptococci (BHCA) - 90%, anaerobic (+) grams of cocci, aerobic grams (-) sticks and bacteria. Each of these pathogens, with the exception of GBSA, rarely rarely causes necrotizing fasciitis on its own. The disease occurs when the combination of pathogens and synergy enters the subcutaneous tissue and the fascia. Synergies between aerobic and anaerobic can lead to necrosis of the skin, soft tissue and destruction of the fascia. Bacterial gangrene, in which the subcutaneous tissues are mainly affected and the fascia is not affected, is caused by the combination of non-hemolytic microaerophilic streptococci and S. aureus. Streptococcal gangrene is caused only by toxigenic strains of GBSA. It is generally a rapidly progressing infection, accompanied by symptoms of severe intoxication (streptococcal toxic shock syndrome).

Slight injuries, insect bites, drug reactions, non-aseptic injections, perianal abscesses, serious injuries and surgical procedures predispose to necrotizing infections, but they can develop without predisposing factors.

The most frequent localization of the process is the perineum, then the lower limbs are involved in the process.

Diagnosis of necrotic skin and soft tissue infections is difficult due to the frequent absence of external symptoms of infection. For early recognition of NIs, a detailed medical history and a thorough physical examination of the patient are important. There is a general deterioration, an increase in heart rate, a significant increase in temperature. Skin anesthesia is probably an important symptom of necrotizing fasciitis, probably caused by the death of the nerves located in the underlying tissues altered by necrosis. Some patients with necrotizing fasciitis have local pain at the site of the lesion, hyperemia, fever, and swelling.

A necrotizing infection can manifest as a flaccid phlegmon or a small ulcer. Subject to the standards of examination of a patient with a common or suspected infection, even a doctor who has never met her can diagnose a necrotizing infection. The most important approach for any skin or soft tissue infection is to be wary of the possibility of a necrotizing infection. This approach allows you to quickly suspect a diagnosis, and already in the future, the doctor confirms or refutes it.

In each case of necrotizing infection, a clostridial and fungal etiology should be suspected, despite their rarity. Clostridial infection should be suspected if muscle necrosis is accompanied by symptoms of severe intoxication with signs of damage to the central nervous system. Clostridial exotoxin causes massive tissue necrosis with mild hyperemia and fibrin deposition or neutrophilic infiltration of affected tissue. The skin acquires a bronze color, then hemorrhagic blisters appear, a skin necrosis and a frizz develop. Clostridial muscle necrosis is characterized by excruciating pain. Patients with malignant tumors are particularly prone to necrotizing infections caused by Clostridium septicum.

Neither with a clostridial etiology nor with a non-clostridial etiology of the infection, there is initially no pronounced sign of skin necrosis. The non-clostridial infection is accompanied by erythema, pain and swelling, resembling common cellulitis. The presence of a necrotizing infection is indicated by the ineffectiveness of antibiotics, rapid progression or the development of systemic manifestations. Moderate to severe pain in the skin above the lesion is typical of a GBSA infection leading to gangrene.

The diagnostic value is the frequent combination of necrotizing soft tissue infection with diabetes mellitus, hypertension, heart failure, obesity, renal failure, cancer, exhaustion, atherosclerosis, autoimmune diseases, AIDS, as well as their frequency in patients with more 60 years old. In 30% of cases, IN occurs in healthy people.

Necrotizing soft tissue infection is reliably confirmed by computed tomography, MRI. A biopsy allows you to make a diagnosis based on typical histological changes. Aspiration biopsy is possible.

Patients with gangrenous infection often have thrombocytopenia and sepsis. Hypocalcemia is sometimes observed, accompanied by muscle contractions, Hvostek symptoms, carporadial spasms. All patients develop neutrophilic leukocytosis. The permanent signs of necrotizing fasciitis are a leukocytosis of more than 14 · 109 / l, a decrease in plasma sodium below 135 mmol / l, an increase in urea of more than 150 mg / l. The presence of gas in the tissues is often detected radiologically. Crepitus is detected in 50% of patients. Bubbles, skin necrosis, serous-purulent exudate and an unpleasant odor are late manifestations of necrotizing infection. Most patients develop hypoproteinemia and hypoalbuminemia. A deficit of water and electrolytes develops, although their loss does not occur. The formation of edema leads to hypovolemia and, sometimes, hypotension. Unwanted laboratory signs are a serum creatinine level above 20 mg / l and a high level of lactic acid in the blood.

With any infectious gangrene, general symptoms of infection are observed. Toxic shock syndrome develops in almost 10% of patients with a CHD etiology of necrotizing infection. The development of occlusion of the microvascularization leads to a delay in skin necrosis. If the correct treatment is not started quickly, sepsis and multi-organ failure develop. The swelling of the tissues with partial or complete divergence of the postoperative sutures also makes it possible to suspect a necrotizing infection. In this case, take biopsy material from the operating room and examine all layers of the skin, subcutaneous tissue, fascia, muscles and peritoneum.

Patients should be treated jointly by an infectious disease specialist, a resuscitator and a surgeon. Given the result of a Gram stain, three antibiotics are administered intravenously before the result of the microbiological examination: penicillin (or ampicillin) + clindamycin (or metronidazole) + gentamicin (or another aminoglycoside). Clindamycin is effective in patients with GBSA infection, which is accompanied by toxic shock syndrome, because it inhibits the production of toxin by the pathogen. Carbapenems can be used. An antibiotic for postoperative treatment is selected in accordance with the results of a microbiological study. Empirical therapy often does not cover enterococci. It is necessary to prevent tetanus with tetanus toxoid and tetanus toxoid immunoglobulins.

Before surgery, it is necessary to perform infusion therapy and stabilize the hemodynamics. Intravenous antibiotic therapy is always done before surgery. With the BHCA etiology of necrotizing fasciitis, a significant improvement can be observed with the intravenous administration of gamma globulin.

Although the clinical course of bacterial gangrene is slow, it must first be treated as an infectious gangrene. In this case, the treatment should be conservative, although all necrotic tissue should be removed surgically.

As soon as the patient's condition allows general anesthesia, a complete necrectomy is performed. But even if the septic shock cannot be stopped by an infusion therapy and the introduction of antibiotics, the operation cannot be postponed, since the septic condition can only be eliminated after removal of the necrotic tissues.

Clostridial infection may be recognized during surgery for necrotic muscle changes. During surgery, a complete necrectomy is performed. The decision to amputate a limb with Clostridial gangrene must be made as soon as possible, which saves the patient's life. Large doses of penicillin are administered intravenously and for allergies, clindamycin or metronidazole are used. In clostridial etiology, after surgery, hyperbaric oxygenation must be performed, which acts bacteriostatically on the pathogen and prevents the production of α-toxin. Dead tissue left after necrectomy reduces the effectiveness of HBO, so necrectomy should be done very carefully during the first procedure.

The surgeon always follows three principles: complete excision of all necrotic tissue, extensive drainage and complete hemostasis. The key to successful treatment of patients with necrotizing skin and soft tissue infections is early diagnosis and intensive medical and surgical treatment. An increase in the period between hospitalization and surgery leads to an increase in mortality.