Soft tissue infections like gas gangrene and necrotizing fasciitis are life-threatening bacterial infections that can cause tissue death. Gas gangrene is caused by Clostridium bacteria entering wounds and producing toxins and gas. It requires urgent surgical debridement and antibiotics like penicillin and clindamycin. Necrotizing fasciitis is a rapidly progressive infection of the fascia and soft tissue that spreads along tissue planes. It is classified into types based on causative organisms and risk factors include diabetes and trauma. On exam, it causes skin bullae, discoloration, and edema. Treatment involves emergency radical debridement, broad-spectrum IV antibiotics, and consideration of hyperbaric oxygen. Both

1. Soft Tissue Infection
Nashrul Hadi

2. GAS GANGRENE
• Gas gangrene also known as "Clostridial
myonecrosis", and "Myonecrosis"
• It is a bacterial infection that produces gas in
tissues in gangrene.

3. Epidemiology
•demographics
– Male : female ratio
• no sexual predilection
•location
– buttocks, thigh, perineum

4. • risk factors
– Posttraumatic (associated with C perfringens)
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MVA (most common)
crush injuries
gunshot wounds with foreign bodies
burns and frostbite
IV drug abuse
– Postoperative
• bowel resection or perforation
• biliary surgery
• premature wound closure
– Spontaneous
• colon cancer (associated with C. septicum)
• neutropenia

5. • Pathophysiology
– Clostridial species
• Clostidium perfringens (most
common), Clostridium novyi, Clostridium
septicum
• found in soil and gut flora
• gram-positive obligate anaerobic sporeforming rods that produce exotoxins (e.g.
C. perfringens alpha toxin)
– causes muscle necrosis and vessel
thrombosis
– can cause hemolysis and shock
• incubation period <24h
• gas produced by fermentation of glucose
– main component is nitrogen
– other bacteria include E.
coli, Pseudomonas aeruginosa, Proteus
species, Klebsiella pneumoniae

6. • Prognosis
– overall 25% mortality
– 50% mortality if bacteremic
– 100% mortality if treatment is delayed
– poorer prognosis for older patients with
comorbidities.

7. Clinical Features
• History
– recent surgery to GI or biliary tract
• Symptoms
– Triad
• suddent progressive pain out of proportion to injury
– from thrombotic occlusion of large vessels
• tachycardia not explained by fever
• feeling of impending doom

8. • Physical exam
– sweet smelling odor
– swelling, edema, discoloration and ecchymosis
– blebs and hemorrhagic bullae
– "dishwater pus" discharge
– crepitus
– altered mental status

9. Investigation
Radiographs
•Findings
– linear streaks of gas in soft tissues

10. • Labs
– Elevated LDH
– Elevated WBC
– Metabolic acidosis and renal failure
• Histology
– Gram stain reveals Gram-positive bacilli
– absence of neutrophils
• lack of acute inflammatory response is hallmark
of gas gangrene
• Culture
– blood culture rarely grows Clostridial species
• DDx
– Necrotizing Fasciitis

11. Treatment
• Nonoperative
– high dose IV antibiotics
• 1st line is penicillin G and clindamycin
• alternative treatment is erythromycin, tetracycline or ceftriaxone
– clindamycin and tetracycline inhibit toxin synthesis
– hyperbaric O2
• indications
– useful adjunct
• outcomes
– effectiveness of HBO2 is inconclusive
• Operative
– radical surgical debridement with fasciotomies
• indications
– 1st line treatment is surgical

12. Complication
• Shock
• Renal failure
– both mediated by TNF alpha, IL-1, IL-6

13. NECROTIZING FASCIITIS
INTRODUCTION:
•Necrotizing fasciitis is a rapidly progressive
inflammatory infection of the fascia, with
secondary necrosis of the sub cutaneous tissue.
•It is a life threatening infection that spreads
along soft tissue planes.

14. • Risk factors
– immune suppression
• diabetes
• AIDS
• cancer
– bacterial introduction
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IV drug use
hypodermic therapeutic injections
insect bites
skin abrasions
abdominal and perineal surgery
– other host factors
• obesity
• Associated conditions
– cellulitis
• overlying cellulitis may or may not be present

15. • Prognosis
– life threatening infection
• mortality rate of 32%
• mortality correlates with time to surgical intervention

16. Necrotizing Fasciitis Classification
Type
Organism
Characteristics
Type 1
Polymicrobial
Typical 4-5 aerobic and
anerobic species cultured:
• non-Group A Strep
• anaerobes including Clostridia
• facultative anaerobes
• enterobacteria
• Synergistic virulence between
organisms
• Most common (80-90%)
• Seen in immunosuppressed (diabetics and
cancer patients)
• Postop abdominal and perineal infections
Type 2
Monomicrobial
• Group A β-hemolytic Streptococci is
most common organism isolated
Type 3
Marine Vibrio vulnificus
(gram negative rods)
Type 4
MRSA
• 5% of cases
• Seen in healthy patients
• Extremities
• Marine exposure

17. Clinical Features
• Symptoms
– early
• localized abscess or cellulitis with
rapid progression
• minimal swelling
• no trauma or discoloration
– late findings
• severe pain
• high fever, chills and rigors
• tachycardia

18. • Physical exam
– skin bullae
– discoloration
• ischemic patches
• cutaneous gangrene
– swelling, edema
– dermal induration and erythema
– subcutaneous emphysema (gas producing
organisms)
• DDx
– Gas Gangrene

19. Investigation
• Radiographs
– not required for diagnosis or treatment
• Biopsy
– only method of definitive diagnosis
– surgical intervention should not be delayed to
obtain

20. • LRINEC Score
– score > 6 has PPV of 92% of having necrotizing fasciitis
– CRP (mg/L) ≥150: 4 points
– WBC count (×103/mm3)
• <15: 0 points
• 15–25: 1 point
• >25: 2 points
– Hemoglobin (g/dL)
• >13.5: 0 points
• 11–13.5: 1 point
• <11: 2 points
– Sodium (mmol/L) <135: 2 points
– Creatinine (umol/L) >141: 2 points
– Glucose (mmol/L) >10: 1 point

21. Management
• Operative
– Emergency radical debridement with broadspectrum IV antibiotics
• indications
– whenever suspicion for necrotizing fascitis
• operative findings
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liquified subcutaneous fat
dishwater pus
muscle necrosis
venous thrombosis
• technique
– hemodynamic monitoring with systemic resuscitation is
critical
– hyperbaric oxygen chamber if anaerobic organism identified

22. – antibiotics
• initial antibiotics
– start empirically with penicillin, clindamycin, metronidazole,
and an aminoglycoside
• definitive antibiotics
– penicillin G
» for strep or clostridium
– imipenem or doripenem or meropenem
» for polymicrobial
– add vancomycin or daptomycin
» if MRSA suspected
02/05/14

23. – Amputation
• indications
– low threshold for amputation when life threatening

24. Reference
• Orthobullet
02/05/14