Signs and Symptoms
History
- Fever (may be absent or suppressed by medications)
- Altered mental status
- Chronic medical conditions
- IV drug use
- Nausea, vomiting, diarrhea (with GABHS)
- Skin (may have no skin findings early, just severe pain):
- Rapid progression of pain and swelling of involved area
- First 24 hr: Rapid development of local swelling, warmth, erythema, and tenderness
- 1-5 d: Purple and blue discoloration, blisters and bullae develop (often hemorrhagic), regional anesthesia
- Foul-smelling thin fluid (“dishwasher” pus from necrosis of fat and fascia)
- Progressive infection despite antibiotics
ALERT |
| NSAID use is associated with worse outcomes - unclear if this is because it masks signs and symptoms or due to suppressing neutrophil function |
Physical Exam
- Systemic toxicity:
- Fever
- Tachycardia
- Tachypnea
- Hypotension
- Altered mental status
- Severe pain out of proportion to physical exam findings
- Skin:
- Erythema
- Tense edema
- Grayish or dark wound drainage
- Vesicles or bullae
- Necrosis
- Ulcers
- Crepitus (pathognomonic but present in only 10-37% of cases)
- Pain that extends past margin of visible infection or palpable induration
- Cutaneous anesthesia (from regional destruction)
- Extremities affected more often than torso or perineum
Pediatric Considerations |
- Most common presenting symptoms:
- Localized pain (97%)
- Rash (73%)
- Hypotension, altered mental status, and other signs of shock are much less common
|
Essential Workup
- Diagnosis can be difficult
- Careful exam for the aforementioned signs and symptoms in high-risk patients
- NSTIs must be suspected in patients who appear very ill and have pain out of proportion to physical findings
- Diagnosis may require incision and probing of tissue:
- “Finger test” positive if finger easily dissects from incision down through fascia or “dishwater” pus results
Diagnostic Tests & Interpretation
Lab
- CBC with differential:
- WBC ↑ with left shift
- Hct ↓
- Metabolic panel:
- Na ↓
- Renal function ↑ Cr
- Calcium level ↓ (from extensive fat necrosis)
- albumin ↓
- AST ↑
- Disseminated intravascular coagulation panel (coagulopathy)
- Creatine phosphokinase ↑
- C-reactive protein ↑ >150
- Lactate ↑
- Gram stain and aerobic/anaerobic cultures of wound or tissue biopsy
- Blood cultures (type I 20% yield, type II 60% yield, may not include all culprit organisms)
Imaging
- X-rays to detect soft tissue gas:
- Pathognomonic, but present in fewer than half of cases
- CT scan:
- May be more helpful than plain x-rays in detecting SC air
- Enhanced CT with absence of fascial enhancement specific for NSTIs
- May also identify deep abscess or other cause of infection
- MRI:
- Can delineate extent of spread of the infection
- Nonspecific fascial thickening appears similar to general inflammation from other causes
- Can be overly sensitive and time consuming
- US findings:
- Fascial thickening and fluid in the fascial plane
- SC soft tissue edema, air, or abscess
ALERT |
| Imaging should not delay surgical debridement with crepitus or rapidly progressive infection - earlier surgery has better outcomes |
Diagnostic Procedures/Surgery
- All patients with suspected NSTI should undergo early surgical debridement
- Deep incisional biopsy and cultures are the gold stand ard for diagnosis
- LRINEC score is not sensitive or specific
Differential Diagnosis
- Cellulitis
- Gas gangrene
- Pyoderma gangrenosum
- Pyomyositis
Prehospital
- IV fluid resuscitation
- Manage airway as necessary
Initial Stabilization/Therapy
Manage airway and resuscitate as indicated:
- Rapid-sequence intubation as needed
- Vital signs and cardiac monitoring
- IV access and aggressive fluid resuscitation
- Care per current sepsis guidelines:
- Caution: MAP much greater than 65 from pressors may decrease peripheral perfusion
ED Treatment/Procedures
- Antibiotics: Early broad coverage of aerobic gram-positive and gram-negative organisms and anaerobes
- Treat MRSA until excluded:
- Clindamycin suppresses exotoxins and cytokine production in streptococcal infections/toxic shock
- Surgical consultation:
- Early debridement of all necrotic tissue with fasciotomy and drainage of fascial planes is paramount
- Hyperbaric oxygen as an adjunct:
- Research conflicting, should not delay surgery
- May result in greater tissue salvage and survival
- IV immunoglobulin (IVIG):
- Controversial, not recommended by IDSA
- May be beneficial in NSTI caused by group A streptococcal infection
- Observe for major complications including acute respiratory distress syndrome, renal failure, myocardial irritability and cardiomyopathy, and DIC
ALERT |
| Clindamycin therapy should be initiated as soon as possible when group A streptococcal or Clostridium infection is suspected |
Medication
(Peds daily doses should not exceed adult daily doses)
- Ceftriaxone: 2 g IV q24h (peds: 100 mg/kg/dose IV q24h)
- Ciprofloxacin: 400 mg IV q12h
- Clindamycin: 900 mg IV q8h (peds: 10 mg/kg/dose IV q6h)
- Daptomycin: 4 mg/kg/dose IV q24h
- Gentamicin: 2 mg/kg/dose IV q8h (peds: 2 mg/kg/dose IV q8h)
- Doxycycline: 100 mg IV q12h
- Imipenem/cilastatin: 1,000 mg IV q6h (peds: 25 mg/kg/dose IV q6h)
- Levofloxacin: 750 mg IV q24h
- Linezolid: 600 mg PO/IV q12h (peds: 10 mg/kg/dose PO/IV q8h)
- Meropenem: 1 g IV q8h (peds: 20 mg/kg/dose IV q8h)
- Metronidazole: 500 mg IV q8h (peds: 13.33 mg/kg/dose (40 mg/kg/d) IV q8h)
- Penicillin G: 2-4 million units IV q4-6h (peds: 60,000-100,000 U/kg/dose IV q6h)
- Piperacillin/tazobactam: 3.375-4.5 g IV q6h (peds: 75 mg piperacillin/kg/dose IV q6h)
- Tigecycline: 100 mg IV × 1 then 50 mg IV q12h (limited peds data: 1.2 mg/kg/dose IV q12h)
- Vancomycin: 15-20 mg/kg/dose IV q8-12h (peds: 15 mg/kg/dose IV q6h)
First Line
Recommended initial ED combination therapy:
- Piperacillin/tazobactam + vancomycin + clindamycin
Only narrow antibiotics if type definitively confirmed:
- Type I infections:
- Piperacillin/tazobactam + vancomycin + clindamycin
- OR imipenem/cilastatin, meropenem, or ertapenem
- Severe penicillin hypersensitivity: Clindamycin + aminoglycoside or fluoroquinolone
- Type II infections (Streptococcus):
- Clindamycin + penicillin
- Severe penicillin hypersensitivity: Vancomycin, linezolid, or daptomycin
- Type III infections (aquatic organisms):
- Doxycycline + ceftriaxone
Disposition
Admission Criteria
- All patients with an NSTI must be admitted for surgical debridement, IV antibiotics, and supportive care
- Most patients will require ICU-level care
Discharge Criteria
No patient with NSTI should be discharged from the ED
Issues for Referral
After stabilization with antibiotics and surgical debridement, consider referral for complex wound care and adjunctive hyperbaric oxygen treatment
- BonneSL, KadriSS. Evaluation and management of necrotizing soft tissue infections . Infect Dis Clin North Am. 2017;31:497-511.
- GohT, GohLG, AngCH, et al. Early diagnosis of necrotizing fasciitis . Br J Surg. 2014;101:e119-e125.
- HusseinQA, AnayaDA. Necrotizing soft tissue infections . Crit Care Clin. 2013;29:795-806.
- StevensDL, BisnoAL, ChambersHF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America . Clin Infect Dis. 2014;59:e10-e52.
- StevensDL, BryantAE. Necrotizing soft-tissue infections . N Engl J Med. 2017;377:2253-2265.
See Also (Topic, Algorithm, Electronic Media Element)