Emergency Medicine · Year 3 · from Emergency Medicine

Case 2: Necrotizing Fasciitis - The Rapidly Progressive Infection

Patient Demographics

• Age: 52 years
• Sex: Male
• Occupation: Construction worker

Chief Complaint

"My leg is killing me and getting worse by the minute."

History of Present Illness

A 52-year-old male presents with severe left lower leg pain that began 24 hours ago. He reports a minor scrape on his shin 3 days ago while at work. Yesterday he noticed redness around the wound and today the pain has become excruciating - "worse than anything I've ever felt." He has diabetes and admits to poor glucose control. His wife notes the redness has been "spreading fast" and his skin looks "weird."

Initial Assessment

ESI Level: 1 - Suspected necrotizing soft tissue infection

First Impression:

• Appearance: Writhing in pain, appears toxic
• Work of breathing: Tachypneic
• Circulation: Tachycardic, diaphoretic

Vital Signs:

• Heart rate: 128 bpm
• Blood pressure: 98/62 mmHg
• Respiratory rate: 24 breaths/min
• SpO2: 96% on room air
• Temperature: 39.2C (102.6F)
• GCS: 15

Key Clinical Feature: Pain Out of Proportion

Classic Finding:

• Patient describes 10/10 pain
• On exam: Minimal erythema visible
• Pain SIGNIFICANTLY exceeds apparent physical findings - RED FLAG for necrotizing fasciitis

Primary Survey

Airway: Patent Breathing: Tachypneic, clear lungs Circulation: Tachycardic, hypotensive Disability: Alert, in severe distress Exposure: Left lower leg examination critical

Lower Extremity Examination

Left Lower Leg:

• Wound: Small healing scrape over anterior shin
• Erythema: Expanding margins (wife marked border 2 hours ago - now 4cm beyond)
• Skin changes: Dusky/gray discoloration, tense edema
• Bullae: Early hemorrhagic bullae forming
• Crepitus: Present on palpation (subcutaneous gas!)
• Temperature: Paradoxically cool in center, warm periphery
• Sensation: Decreased over affected area (nerve involvement)

LRINEC Score (Laboratory Risk Indicator for Necrotizing Fasciitis):

Diagnosis - Clinical, Not Radiographic

Necrotizing Fasciitis - Clinical Criteria:

• Pain out of proportion to exam ✓
• Rapidly progressive ✓
• Systemic toxicity ✓
• Skin changes (dusky, bullae) ✓
• Crepitus (gas in tissue) ✓

DO NOT DELAY FOR IMAGING - This is a clinical and surgical diagnosis

Immediate Management

Resuscitation:

1. Two large-bore IVs
2. Aggressive fluid resuscitation
3. Blood cultures obtained
4. Lactate: 6.2 mmol/L

Antibiotics (Broad-Spectrum, High-Dose):

• Vancomycin 25 mg/kg IV (MRSA, strep)
• Piperacillin-tazobactam 4.5g IV (broad coverage)
• Clindamycin 900mg IV (toxin suppression - critical for strep)

Emergency Surgical Consultation:

• Called immediately
• Patient taken to OR within 90 minutes of ED arrival

Secondary Survey

SAMPLE History:

• Symptoms: Severe leg pain, fever, spreading redness
• Allergies: None
• Medications: Metformin, glipizide
• PMH: Type 2 diabetes (poorly controlled, HbA1c 10.2%), peripheral vascular disease
• Last Meal: Breakfast today
• Events: Minor trauma 3 days ago

Risk Factors for Necrotizing Fasciitis:

• Diabetes mellitus ✓
• Peripheral vascular disease ✓
• Immunosuppression ✓
• Trauma/wound ✓
• Obesity
• IVDU

Diagnostic Testing

Labs:

• WBC: 24,800 with left shift
• Na: 131 mEq/L
• Cr: 2.1
• Glucose: 382 mg/dL
• Lactate: 6.2 mmol/L
• CRP: 312 mg/L
• Procalcitonin: 22.4 ng/mL
• CK: 1,840 IU/L (muscle involvement)

Blood Gas: pH 7.28, metabolic acidosis

Imaging (obtained rapidly, did NOT delay surgery):

• X-ray: Subcutaneous gas visible
• CT (if stable): Gas tracking along fascial planes

Operative Findings

Surgical Exploration:

• Incision revealed grayish, necrotic fascia
• "Dishwater" purulent fluid
• Easy separation of tissue planes (fascial necrosis)
• Thrombosed vessels
• Extensive debridement required
• Muscle involvement (myonecrosis) present

Extent:

• Radical debridement from mid-thigh to ankle
• Multiple return trips to OR for serial debridement

Tissue Cultures: Group A Streptococcus (Strep pyogenes)

Microbiology of Necrotizing Fasciitis

This patient: Type II - Group A Streptococcal necrotizing fasciitis ("flesh-eating bacteria")

Post-Operative Management

ICU Care:

• Mechanical ventilation (24 hours)
• Vasopressors (norepinephrine)
• Serial debridements (OR x4)
• Wound VAC placement
• Nutrition support

Antibiotic Duration:

• Continued IV antibiotics until source control achieved
• De-escalated to penicillin + clindamycin based on sensitivities
• Total course: 14 days

IVIG Consideration:

• Considered for streptococcal toxic shock syndrome
• Given 1g/kg

Outcome

Hospital Course:

• ICU: 5 days
• Total hospitalization: 28 days
• Required skin grafting
• Extensive rehabilitation

Limb Salvage: Successful (avoided amputation)

Teaching Points

1. Pain out of proportion is the key finding: Disproportionate pain with minimal skin findings = necrotizing fasciitis until proven otherwise
2. Clinical diagnosis, surgical emergency: Do NOT delay for imaging
3. Time is tissue: Mortality increases 7-9% for each hour of surgical delay
4. Clindamycin is essential: Suppresses toxin production (especially for streptococcal)
5. Serial debridements: One operation is rarely sufficient
6. LRINEC score: Can support diagnosis but don't rely on it to rule out
7. Mortality remains high: 20-40% despite optimal treatment
8. Crepitus is late finding: Absence of crepitus doesn't rule out necrotizing fasciitis

Clinical Image

Image Description: CT scan of the lower extremity demonstrating gas tracking along the fascial planes (arrows), consistent with necrotizing fasciitis. Subcutaneous gas appears as dark (low density) areas within the soft tissue.

Attribution: Image from Radiopaedia.org, Case courtesy of Dr. Henry Knipe. Licensed under CC BY-NC-SA 3.0. Source: https://radiopaedia.org/cases/necrotizing-fasciitis-4

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