Necrotizing fasciitis

Life‑threatening, rapidly progressive infection of the fascia and deep soft tissues ("flesh‑eating" disease) causing necrosis of subcutaneous tissue.

• It's a true surgical emergency with high mortality if not promptly treated. Early recognition and aggressive intervention (surgery + antibiotics) are critical and often tested on exams (classic "pain out of proportion" scenario).

• Severe pain out of proportion in an area of recent skin trauma (cut, surgical wound, ulcer) that rapidly worsens. Early on, the overlying skin may look surprisingly normal or only mildly erythematous despite excruciating deep pain.
• Within 1-2 days, escalating swelling, tense edema, and spreading redness develop. Skin may turn dusky purple with bullae (blisters) and crepitus (gas in tissue). The area can become numb (loss of sensation due to nerve destruction) even while infection spreads.
• Systemic signs: high fever, tachycardia, hypotension and confusion (sepsis) often accompany advanced cases. Common sites are limbs and perineum (Fournier's gangrene in diabetic men is necrotizing fasciitis of the genitals). Risk factors include diabetes, peripheral vascular disease, immunosuppression, alcoholism, and IV drug use, though it can also occur in healthy individuals after minor injuries.

1. Maintain a high index of suspicion: if a patient has a rapidly spreading soft-tissue infection with disproportionate pain or systemic toxicity, do not dismiss it as simple cellulitis—consider necrotizing fasciitis and escalate care.
2. Use the LRINEC score (Laboratory Risk Indicator for Necrotizing Infection) as a tool: it assigns points for CRP, WBC, hemoglobin, sodium, creatinine, glucose. A score ≥6 is worrisome (≥8 highly predictive), but a low score doesn't fully exclude NF. Always prioritize clinical judgment over lab scores.
3. If necrotizing fasciitis is suspected, do not delay definitive treatment. Begin broad-spectrum antibiotics and obtain emergency surgical consultation immediately. Imaging (CT or MRI) can show fascial thickening or gas and may be useful if time allows, but never wait for imaging in a rapidly deteriorating patient—surgical exploration is the gold standard for diagnosis. In surgery, findings of gray, devitalized fascia with foul "dishwater" fluid confirm the diagnosis.

1. Immediate IV broad-spectrum antibiotics covering Gram-positives, Gram-negatives, and anaerobes (for example, vancomycin + piperacillin/tazobactam + clindamycin). Clindamycin is added to inhibit toxin production (especially for GAS).
2. Urgent surgical debridement is the cornerstone: prompt, extensive removal of all necrotic fascia and tissue. Often multiple surgeries ("washouts") are required until the infection is controlled and all dead tissue is excised.
3. Intensive supportive care in an ICU setting: aggressive fluids and vasopressors for septic shock, pain control, and organ support as needed. Adjunctive therapies like IVIG (for streptococcal toxic shock) or hyperbaric oxygen may be considered in select cases, but never as a substitute for surgery.

• On exams, "pain out of proportion" in a skin infection is a red flag hinting at necrotizing fasciitis.
• Always include clindamycin in the antibiotic regimen for necrotizing fasciitis – it helps suppress streptococcal toxin production (improving outcomes in GAS infections).

• A seemingly minor skin infection with disproportionate pain or rapid deterioration – don't ignore this; it strongly suggests a deep necrotizing infection.
• Any gas in the tissues (crepitus on exam or air on imaging), rapidly spreading discoloration/bullae, or early hypotension in a soft-tissue infection indicates a severe necrotizing process – requires emergent surgical intervention.

1. Suspect necrotizing fasciitis → Call for surgical evaluation immediately (do not wait).
2. Simultaneously, start broad empiric antibiotics and obtain key labs (CBC, CMP, CRP, lactate) ± imaging (CT/MRI if it won't delay OR). Calculate LRINEC score, but don't rely on it solely.
3. If clinical suspicion is high or imaging suggests NF → proceed to emergent surgical exploration. Confirm diagnosis by visualizing necrotic fascia (or doing a bedside finger test probing through subcutaneous tissue). Perform aggressive debridement of necrotic tissue → send cultures → ICU for ongoing care (repeat debridements and tailor antibiotics based on culture results).

• Diabetic patient with a rapidly expanding red swollen leg, exquisite pain beyond expected, fever, and crepitus → Necrotizing fasciitis (polymicrobial, Type I).
• Middle-aged man with severe scrotal pain and swelling, high fever, and subcutaneous gas in the perineum → Fournier's gangrene (necrotizing fasciitis of the perineum).