Wet gangrene

Complication of the decay of soft tissues by a bacterial infection leads to melting (colliquation) or purulent necrosis, diagnostically defined as infectious or wet gangrene. [1]

Causes of the wet gangrene

Wet gangrene can have causes such as severe burns, soft tissue ulcers, frostbite, or trauma. Most often, there is wet gangrene of the lower extremities: fingers, feet, lower legs - as they are prone to edema with impaired blood flow and capillary circulation. More information in the materials:

• Gangrene of the legs
• Gangrene of the foot

This complication often develops in people with diabetes who injure a toe or foot. Wet gangrene in diabetes is considered in the article -  Dry and wet gangrene of the toes in diabetes mellitus [2]

Unlike dry (ischemic) gangrene, when wet, there is always a causative agent of necrosing infection: group A β-hemolytic streptococcus (Streptococcus pyogenes), staphylococcus (Staphylococcus aureus, Staphylococcus epidermidis), Proteus (Proteus mirabilis), Pseudomonas aeruginosa anaerobic bacteria Clostridium spp., E. Coli (Escherichia coli), enterobacteria (including Klebsiella aerosacus), bacteroides (Bacteroides fragilis). [3]

In addition, if, with dry gangrene, a microbial infection begins to develop in dead tissues, then it, especially in diabetics and HIV-infected people, can develop into a wet one. [4]

Risk factors

For the development of wet gangrene, risk factors are:

• injuries, first of all, deep burns, frostbite, prolonged mechanical (compression) impact, stab wounds, etc.;
• infection of open wounds;
• diabetes mellitus - with trophic ulcers on the legs and diabetic foot syndrome;
• atherosclerosis and chronic peripheral vascular disease of the lower extremities, accompanied by soft tissue ischemia;
• long-term smoking, chronic alcoholism;
• intracavitary surgery.

Pathogenesis

The mechanism of development, that is, the pathogenesis of wet gangrene, is associated with the penetration of infection (invasion) into deeper tissues - into the intercellular space and into the cells - and their edema under the influence of toxins and enzymes produced by bacteria (hyaluronidase, neuraminidase, lecithinase, plasma coagulase, etc.)... [5], [6]

This leads to blockage of venous and lymphatic outflow and blood flow to tissues with cessation of their nutrition and the impossibility of blood leukocytes and phagocytes to resist the rapid multiplication of bacteria in the area of alteration. As a result, there is a development and exacerbation of infection with  necrosis  (necrosis) and purulent fusion of tissues. [7]

Read more in the publication -  Gangrene

Symptoms of the wet gangrene

The first signs - at the initial stage of wet gangrene - appear in the form of localized swelling (edema) and redness, as well as general subfebrile fever (with chills) and severe aching pain.

As the pathological process progresses, which occurs very quickly in this type of gangrene, other symptoms appear: the area of dead tissue can turn brown-red, purple-violet or greenish-black - with the formation of blisters and ulceration; fragments of non-viable skin and subcutaneous tissue exfoliate; a rather loose, dirty gray scab forms on the dead tissues; exudate of a serous-purulent nature is released, which has a disgusting odor.

At the same time, the border between the dead tissue of the gangrenous area and the healthy tissue — the demarcation line in wet gangrene — is practically absent.

Forms

Specialists identify such types or subtypes of wet gangrene as:

• Fournier's gangrene  (necrotizing fasciitis or necrosis of the connective tissue of the male genitals);
• internal gangrene (or acute gangrenous inflammation) of various tissues and organs - wet gangrene of the intestine, appendix, gallbladder, bile duct, or pancreas;
• synergistic Meleni gangrene or bacterial synergistic gangrene, which can develop in patients after surgery (in the second week after surgery) and is caused by Staphylococcus aureus and streptococcal infection.

Also in Africa and Asia, wet gangrene of the soft tissues of the face or nome is common, caused by Staphylococcus aureus, the anaerobic bacteria Prevotella intermedia, Fusobacterium necrophorum, Tannerella forsythia, pathogenic bacteroids Porphyromonas gingivalis, etc. Live in regions south of the Sahara - in conditions of extreme poverty, unsanitary conditions and constant malnutrition. Experts consider this disease (with a 90% infant mortality rate) to be a consequence of acute necrotizing ulcerative inflammation of the gums. [8], [9]

Complications and consequences

The development and progression of wet gangrene can be rapid and lead to life-threatening complications and consequences.

Toxic compounds produced by bacteria are absorbed and enter the bloodstream, causing general intoxication of the body, multiple organ failure, sepsis and death.

Diagnostics of the wet gangrene

When diagnosing wet gangrene, a complete examination of the affected limb is performed.

Tests include a general and biochemical blood test with a leukocyte count and ESR determination, a coagulogram, an analysis of blood serum for the level of creatinine and lactate dehydrogenase, a sowing of the wound contents (for bacterioscopic examination) or a skin biopsy to determine a microbial culture. [10]

Instrumental diagnostics uses X-ray and ultrasound of soft tissues, CT or MRI angiography .

Differential diagnosis

Differential diagnosis is carried out with abscesses, necrotic erysipelas, infected dermatitis and pyoderma gangrenosum. Dry and wet gangrene are usually differentiated clinically. [11]

Treatment of the wet gangrene

It is necessary to start treatment of wet gangrene as early as possible due to its rapid development, requiring urgent medical attention, including surgical.

In this case, surgical treatment consists in surgical debridement of non-viable tissues - necrectomy.

The main drugs are systemic (parenteral)  antibiotics of a wide spectrum of action , including drugs of the penicillin group, cephalosporins, lincosamides, macrolides and glycopeptide antibiotics. [12]

Additionally, for better tissue healing, physiotherapeutic treatment - hyperbaric oxygenation - can be used  .

Cardinal surgery - amputation of a part of the limb - is carried out with unsuccessful attempts to stop the pathological process with the help of antibacterial drugs. Internal gangrene requires extensive surgery to remove the gangrenous tissue. [13]

Prevention

To avoid the development of wet gangrene, an antiseptic treatment of any wound is necessary. And doctors advise patients with diabetes to protect their feet from traumatic injuries and regularly examine them, since even an unnoticed scratch can become a gateway for infection with the development of a necrotic process in the tissues.

Forecast

Experts consider the prognosis of wet gangrene to be uncertain, since everything depends on its stage at the time of seeking medical help and adequate treatment. How long they live with wet gangrene also depends on this. Without treatment, 80% of patients with gangrene die, after treatment for five years, up to 20% of patients survive. Moreover, according to clinical observations, after amputation of the affected limb below the knee [14] , amputation above the knee was required in 15% of cases  after two years, and a third of cases were fatal.