What is the pathogenesis of Fournier's gangrene?

From the Guidelines

Fournier's gangrene is a rapidly progressive necrotizing fasciitis affecting the genital, perineal, and perianal regions, caused by a synergistic combination of aerobic and anaerobic bacteria, and its pathogenesis involves polymicrobial infection that typically begins with a breach in the skin or mucosa, allowing bacteria to enter and spread rapidly through the fascial planes 1. The infection is usually caused by a combination of bacteria, including Escherichia coli, Bacteroides, Streptococcus, Staphylococcus, and Clostridium species, which produce enzymes that facilitate tissue destruction and bacterial spread. Some key points about Fournier's gangrene include:

• The infection causes thrombosis of subcutaneous blood vessels, leading to ischemia and necrosis of the overlying skin, and this vascular compromise further promotes bacterial growth by creating an anaerobic environment 1.
• Risk factors that predispose individuals to Fournier's gangrene include diabetes mellitus, alcoholism, immunosuppression, local trauma, and urogenital or colorectal infections 1.
• The rapid spread of the infection occurs because the fascial planes of the perineum and genitalia are interconnected, allowing infection to advance quickly along these paths of least resistance 1.
• The resulting tissue destruction causes severe pain, systemic toxicity, and without prompt treatment, can lead to septic shock and death, with a mortality rate that approaches 20–50% in many contemporary series 1. The diagnosis of Fournier's gangrene is mainly clinical, and a focused and detailed medical history as well as a complete physical examination including a careful inspection of the perineum is mandatory, and the most common symptoms include perineal and/or scrotal pain, swelling, and erythema 1. The treatment of Fournier's gangrene includes prompt appropriate antibiotic therapy, hemodynamic support, and early debridement, and early and extensive initial surgical debridement improves survival 1. Some other key points about the treatment of Fournier's gangrene include:
• Surgical intervention should be performed as soon as possible in the presence of high suspicion for Fournier’s gangrene, and subsequent surgical revisions should be planned based on the patient conditions 1.
• The Fournier’s Gangrene Severity Index (FGSI) is a standard score for predicting outcome in patients with FG, and a FGSI score above 9 has been demonstrated to be sensitive and specific as a mortality predictor in patients with Fournier’s gangrene 1.

From the Research

Pathogenesis of Fournier's Gangrene

Fournier's gangrene is a rare, necrotising fasciitis of the external genitalia, perineal or perianal regions, with a higher incidence in males and risk factors including diabetes, HIV, alcoholism, and other immune-compromised states 2. The disease is characterized by an obliterative endarteritis of the subcutaneous arteries, resulting in gangrene of the overlying skin 3.

Risk Factors and Comorbidities

The commonest aetiological event is a minor trauma, with predisposing factors including diabetes mellitus and overweight 4. Other risk factors include long-term alcohol misuse and age over 50 3. The presence of comorbidities such as diabetes mellitus and immune-compromised states increases the risk of developing Fournier's gangrene 2, 3.

Microbiological Characteristics

The disease is often caused by a polymicrobial infection, with 90% of patients exhibiting polymicrobial infection 4. The nidus for the synergistic polymicrobial infection is usually located in the genitourinary tract, lower gastrointestinal tract, or skin 3.

Clinical Presentation

The most common clinical presentation includes:

• Scrotal and labial pain
• Fever
• Abscesses
• Crepitus
• Erythema
• Cellulitis 5 The diagnosis is often made clinically, although radiography can be helpful when the diagnosis or the extent of the disease is difficult to discern 3.

Key Features of Fournier's Gangrene

Some key features of Fournier's gangrene include:

• High mortality rate of 20-30% 2
• Aggressive disease process requiring prompt diagnosis and treatment 2, 5
• Importance of early identification for improved outcomes or survival 5
• Need for rapid and aggressive surgical debridement of necrotized tissue, hemodynamic support, and broad-spectrum parental antibiotics 3, 5