Foot and Ankle cases 26

You are called by the emergency department to see a 50-year-old male who reported a wound on his leg yesterday. He initially did not have any problems, however in the past 4 hours he has noted increased erythema, pain requiring IV narcotics, and tachycardia. The emergency department asks what laboratory information may be helpful in determining if this is necrotizing fasciitis or just cellulitis.

Based upon the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) criteria, which of the following is not of value?

1. CRP

2. WBC

3. Sodium

4. ESR

 

Discussion

The correct answer is (D). Although valuable for nearly every other infectious process in orthopaedics, the erythrocyte sedimentation rate (ESR) is not a component of the LRINEC criteria. The LRINEC criteria have been described as a means of differentiating necrotizing fasciitis from cellulitis. A score is given based upon CRP level (greater or less than 150 mg/L), WBC (less than 15,000, between 15,000 and 25,000, and greater than 25,000), hemoglobin (greater than 13.5, between 11 and 13.5, or less than 11), sodium (greater or less than 135), creatinine (greater or less than 1.6), and glucose (greater or less than 180). With a score less than or equal to 5, there is less than 50% chance of necrotizing fasciitis, however with a score greater than or equal to 8, there is a 75% chance of necrotizing fasciitis.

Upon evaluation of the patient in the emergency department there is a noted waxy appearance of the skin with bullae formation and erythema spreading beyond the borders drawn by the emergency department physician 20 minutes ago (Fig. 5–52). You decide at that point to bring the patient to the operating room for an emergent irrigation and debridement. In the operating room there is murky dishwater fluid at the level of the fascia. You take cultures at this point and perform an irrigation and debridement using your gloved finger to undermine skin in regions which are affected.

 

 

 

Figure 5–52 Clinical image of the left leg demonstrating bullae with surrounding erythema.

 

Which of the following is the most likely causative organism?

1. Staphylococcus aureus

2. Escherichia coli

3. Vibrio vulnificus

4. Polymicrobial

5. Group A beta hemolytic Streptococcus

 

Discussion

The correct answer is (D). Necrotizing fasciitis can be classified into three groups based upon causative organism. The most common type is type 1, which is caused by a polymicrobial infection with multiple organisms growing on culture. Type 2 necrotizing fasciitis is caused by Group A beta hemolytic streptococci or methicillin-resistant Staphylococcus aureus. This is the typical “flesh eating bacterial” presentation. This is more typical in healthy individuals. Type 3 necrotizing fasciitis is caused by marine organisms such as vibrio vulnificus and often occurs in patients with liver disease. This is the least common form of

necrotizing fasciitis.

 

Following surgery, he is admitted to the ICU. Initial Gram stain from intraoperative cultures comes back with gram-positive cocci in clusters. In addition to vancomycin, which other antibiotic should be added to the treatment protocol?

1. Zosyn

2. Penicillin

3. Cefazolin

4. Clindamycin

 

Discussion

The correct answer is (D). Based upon coverage of varying forms of necrotizing fasciitis, the addition of clindamycin seems to provide the best coverage for all variations of gram-positive Gram stains. Clindamycin inhibits exotoxin production of staph aureus. In addition, it has been shown to blunt the systemic affects of the disease. Finally, it has been demonstrated to clinically decrease the in-house mortality of necrotizing fasciitis.

Postoperatively, he is relatively stable in the ICU. Based upon the degree of necrosis present and how sick the patient was at initial surgery, you decide to take him back to the operating room at 24 hours for a repeat irrigation and debridement. In the operating room again you notice that there is skin which can be undermined with a gloved finger along the posterior medial calf. This skin does not bleed when cut.

Based upon these findings you decide to:

1. Perform an amputation

2. Debride all necrotic skin edges back to viable tissue

3. Utilize this tissue as a biologic dressing

4. Remove all skin from the extremity and place a wound vac

 

Discussion

The correct answer is (B). Amputation, although frequently encountered in patients with necrotizing soft tissue infections, is not indicated at this point as he is clinically stable. As in dealing with debridement of all wounds, it is important to remove all nonviable tissue even if it will require skin graft or flap coverage in the future.

Following the second trip to the operating room, the patient remains stable and

you have placed a wound vac. At the second wound vac change the wound is healthy appearing and surrounding erythema is resolving (Fig. 5–53). In addition to replacing the wound vac and discussing coverage options with the plastic surgeon, you also request assistance from the intensivist service to provide adequate nutrition, glucose control, and antibiotic coverage.

 

 

 

Figure 5–53 Clinical photograph of the limb after multiple irrigations and debridements.

 

The patient asks whether he should have received hyperbaric oxygen instead of surgery. You explain that:

1. There is no role for hyperbaric oxygen in patients with necrotizing soft tissue infections

2. There is a role but it is secondary to surgical debridement and antibiotic therapy

3. Hyperbaric oxygen is an alternative to surgical debridement for early onset necrotizing fasciitis

Discussion

The correct answer is (B). The mainstay of treatment for necrotizing soft tissue infections is aggressive irrigation and debridement, however there are adjunctive

therapies including hyperbaric oxygen, IVIG, and recombinant protein C which may be beneficial in patients with necrotizing soft tissue infections. The evidence for utilizing these are limited to retrospective studies at this point, however there have been some promising results.

 

Objectives: Did you learn...?

 

Classify necrotizing fasciitis by organism?

 

Describe initial antibiotic regimen for treating necrotizing soft tissue infections?

 

Use the LRINEC criteria in differentiating between cellulitis and necrotizing fasciitis?