Makindo Medical Notes

Fournier's gangrene is a rapidly progressing, life-threatening necrotizing fasciitis primarily affecting the perineum. The testicles, penis, and urethra are often spared due to their distinct blood supply from the external iliac arteries.

About

• Severe necrotizing fasciitis involving the scrotum, perineum, and anterior abdominal wall.
• It is a surgical emergency with a high mortality rate, requiring prompt intervention.

Aetiology

• E. coli (common gram-negative aerobic pathogen)
• Bacteroides (most common anaerobe)
• Group A streptococci (e.g., Streptococcus pyogenes)
• Staphylococcus species, including Staphylococcus aureus (sometimes MRSA)
• Other streptococci
• Coliforms (e.g., Enterobacter, Klebsiella)
• Pseudomonas aeruginosa
• Anaerobes including Clostridium species (rare but associated with gas gangrene)
• Polymicrobial infections are often seen (a mix of aerobic and anaerobic bacteria).

Risk Factors

• Diabetes mellitus (present in up to 60-80% of cases, leading to impaired immunity and tissue healing)
• Alcoholism (chronic alcohol use weakens immune response)
• Cirrhosis of the liver (increases susceptibility to infections)
• Immunosuppression (e.g., chemotherapy, systemic lupus erythematosus)
• Crohn's disease or other inflammatory bowel diseases
• HIV/AIDS (immunocompromised state)
• Morbid obesity (leads to skin breakdown and higher infection risk)
• Urinary tract infections or perianal abscesses that act as a portal of entry for pathogens

Clinical Presentation

• Systemic symptoms: tachycardia, hypotension, and fever
• Cyanosis or dusky discoloration of affected areas
• Severe genital pain, rapidly progressing erythema, blistering, and oedema
• Induration and pruritus of the overlying skin
• Subcutaneous crepitus (gas under the skin, suggesting anaerobic infection)
• Wet gangrene with a foul, faeculent odour caused by anaerobic bacteria

Complications

• Septic shock (life-threatening complication from overwhelming infection)
• Diabetic ketoacidosis (in patients with uncontrolled diabetes)
• Disseminated intravascular coagulation (DIC, a serious clotting disorder)
• Acute kidney injury (often secondary to sepsis and shock)
• Multiple organ failure due to overwhelming sepsis
• Prolonged hospital stay and need for intensive care
• Significant tissue loss requiring reconstructive surgery (skin grafts, flaps)

Investigations

• Full blood count (FBC): ↑ WCC (leukocytosis indicates infection)
• U&E: ↑ Creatinine (suggests kidney involvement); ↑ CRP (marker of inflammation)
• Blood cultures: To identify causative organisms, especially in cases of sepsis
• CT or MRI scan: Defines the extent of the disease, shows fascial thickening, fat stranding, and soft tissue gas collection. MRI is especially useful for differentiating necrotizing fasciitis from cellulitis.

Management

• Always contact a Consultant Microbiologist to guide antibiotic therapy
• Always seek an urgent surgical opinion, as immediate surgical debridement is critical
• Initial broad-spectrum antibiotics: Piperacillin/Tazobactam 4.5g tds IV (covers gram-positive, gram-negative, and anaerobes)
• If Penicillin allergy: Clindamycin 600mg qds IV infusion + Gentamicin once-daily IV (Clindamycin inhibits toxin production)
• Repeat surgical debridements are often necessary to remove necrotic tissue
• Consider adjunctive therapies like hyperbaric oxygen (controversial but may aid in tissue healing and kill anaerobic organisms)
• Supportive care: Fluid resuscitation, intensive care, and organ support if necessary