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Shapiro Handout

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Necrotizing Soft Tissue Infections: Update in diagnosis and management Nathan I. Shapiro, MD, MPH Department of Emergency Medicine Beth Israel Deaconess Medical Center Boston, MA
Page 1: Shapiro Handout

Necrotizing Soft Tissue Infections:Update in diagnosis and management

Nathan I. Shapiro, MD, MPH

Department of Emergency Medicine

Beth Israel Deaconess Medical Center

Boston, MA

Page 2: Shapiro Handout

Is it a Necrotizing Soft Tissue Infection?

• CASE 1: 36 yom with no medical problems c/o 0.5 cm laceration to the left index finger due to scraping it on a photocopier yesterday. Also has an atraumatic sore left shoulder.

• CASE 2: 42 yof c/o a stiff right arm and a small cut on the right dorsal ring finger after skiing for one day.

• CASE 3: 86 yom with diabetes, PVD, c/o fever, altered mental status and black purulent vessicles on his scrotum and perineum.

Page 3: Shapiro Handout
Page 4: Shapiro Handout


• Best terminology is Necrotizing Soft Tissue Infection (NSTI)

• Includes:– Necrotizing Fasciitis

– Fournier’s gangrene

– Clostridial “gas” gangrene or myonecrosis

• “necrotic fascia and/or muscle noted on surgery or pathologic exam of debrided tissue”

Page 5: Shapiro Handout

Basics of NSTIs

• Incidence: estimated 1000 cases/year in US

• Mortality has not changed significantly since 1924 – approximate mean mortality of 22% – range of 6-80%

Page 6: Shapiro Handout

Classification of NSTIs

• Type I are polymicrobial (78-92%)– 2.1-4.4 organisms per wound culture

• Type II are monomicrobial (8-12%)– Group A streptococcus– Staphylococcus– Clostridium

Page 7: Shapiro Handout

Type I vs II Necrotizing Fasciitis infective agents

• Bacteroides• Candida• Clostridium• Corynebacterium• Cryptococcus• Eikenella• Enterobacter• Escherichia• Fusobacterium• Histoplasma

•Klebsiella•Neisseria•Pasturella•Proteus•Salmonella•Serratia•Shigella•Staphylococcus•Streptococcus •(non Group A)•Vibrio

• Group A Streptococcus+/- Staph

Type I Type II

Page 8: Shapiro Handout

Diagnostic challange

• Innocent beginnings

• Rapid progression of disease

• Lack of studies on early disease presentation or on progression of early disease

• Ultimate diagnosis is made at surgical exploration

Page 9: Shapiro Handout

Diagnostic Modalities: Clinical Exam

• History…advanced disease easy, early disease utility requires HIGH DEGREE OF SUSPICION.

• Heighten suspicion with the following:– Pain out of proportion to clinical lesion– Tense edema– Edema extends beyond erythema– Purplish skin discoloration– Numbness/weakness in the affected area (possible edema-

induced compartment-like syndrome or directly damaged cutaneous nerves)

Wall et al. J Am Coll Surg 2000;191:227

Page 10: Shapiro Handout

Clinical Exam• Common Hard Clinical Findings??

– Bullae 16-24%

– Necrotic skin 6-3%

– Crepitance 0-36%

– Hypotension 7-11%

– Gas on plain x-ray 32-57%

– Tense edema 23-38%

– Even in late presenting cases, 20-61% lack any hard clinical sign!

Elliott et al. Ann Surg 1996;224:672Wall et al. J Am Coll Surg 2000;191:227

Page 11: Shapiro Handout

Diagnostic Lab Testing for NSTI

• Wall et al. J Am Coll Surg 2000;191:227-231• Wall et al Am J surg 179:2000:17-20• Retrospective case control study of 31

consecutive NSTI vs 328 non-NSTI patients• Model selected by decision tree analysis on vital

signs and laboratory testing• Positive model demonstrated WBC>15.4 or

serum Na<135

Page 12: Shapiro Handout

Diagnostic Lab Testing for NSTIValidation:WBC > 15.4 or Na < 135 in predicting NSTI• 90% sensitivity (74-90%)• 76% specific (71-80%)• Positive Predictive Value (18-35%)• Negative Predictive Value (97-100%)

Page 13: Shapiro Handout

Diagnostic Lab Testing for NSTI

• Pitfalls– Retrospective, case-control study– Retrospective validation

Wall et al. J Am Coll Surg 2000;191:227

Page 14: Shapiro Handout

Radiographic Diagnostic Adjuncts• Plain film x-ray

– May demonstrate gas in tissues (39-75% of cases)– Negative predictive value 62% in Wall et al.

• CT Scan/ Ultrasound– Identify air bubbles in tissue relative to fascial planes

• MRI– With Gd contrast distinguishes perfused vs necrotic

tissue– Defines extent of disease, may help guide surgical


Page 15: Shapiro Handout

Minimum Standard of Care

• Antibiotics

• Surgical Debridement

Page 16: Shapiro Handout

Antibiotic Choices

• Empiric! Cover all the Bases

• Tetanus Status?

• Triple therapy should be standard– Penicillin G– Aminoglycoside– Clindamycin/Metronidazole

Page 17: Shapiro Handout

Choices for SurgeonYou’re on your own….

Page 18: Shapiro Handout

Possible Adjunctive Therapies

• Hyperbaric oxygen (HBO)– Directly toxic to certain anerobes (clostridium)– Improved infection site tissue oxygen tension

improves neutrophil bacteriocidal activity– Case series suggest possible improvements in

mortality, number of surgeries required, wound closure rates

Page 19: Shapiro Handout

Evidence for HBO and NSTI’s

• Riseman, et al. Surgery 1990;108:847• Group 1: 12 std of care vs Group 2: 17 +HBO• (before and after study)• Mortality reduced with HBO, 23 vs 66%• Reduced operative debridements, 1.2 vs 3.3• Pitfalls

– Small patient numbers– No illness severity scoring system– Includes more perineal infections in Group 2

Page 20: Shapiro Handout

Evidence for HBO and NSTI’sHollabaugh, et al. Plast Reconstr Surg. 1998;101:94.

• Group 1: 12 standard of care vs Group 2: 14 +HBO Mortality reduced with HBO 7 vs 42%

• No difference in number of operations required

• Pitfalls– Small patient numbers– No severity of illness scoring system

Page 21: Shapiro Handout

Evidence not supporting HBO in NSTI

• Brown et al. Am J Surg 1994;167:485

• Truncal NSTI: Std care n=24 vs +HBO n=30• APACHE II std used, NS difference in groups• HBO group had more operations/patient: 3.2 vs 1.6• Mortality not significantly improved with HBO

– HBO vs control: 30 vs 42%

• Pitfalls– Small number of patients– 16 HBO group patients transferred for care– HBO group patients younger (51 vs 63 P<0.05)– Multiple centers and possible standard care variation

Page 22: Shapiro Handout

Evidence not supporting HBO in NSTI

• Elliot et al. Ann Surg 1996;224:672• 198 patient consecutive retrospective review• Groups: survivors 148 vs non-survivors n=50• No improvement in mortality with HBO: 25%• Improved rate of wound closure with HBO

– 28 vs 48 days

• Pitfalls– Retrospective uncontrolled study

Page 23: Shapiro Handout

Possible Adjunctive Therapies

• Polyspecific i.v. IgG• Rationale of usage: Strep/staph infections common in NSTI (58%) “Superantigen” toxins commonly secrteted

during infection and cause toxic shock Polyspecific i.v. IgG contains antibodies

neutralizing superantigens Individuals with serious strep NSTIs lack

neutralizing antibodies to superantigens

Page 24: Shapiro Handout

Antigen presenting cell





T-cell Antigenreceptor


Page 25: Shapiro Handout

Algorithmic Approach to R/O NSTI


HighAny Hard Sign

LowNo hard signs

Antibiotics for staph/strepAdmit and observe


Antibiotics for staph/strepD/C with f/u wound check

Triple antibioticsSurgical consultation

Surgical explorationMRI?IV IgG for possible STTS

WBC > 15Na+ < 135


Page 26: Shapiro Handout

My patient has a Necrotizing Soft Tissue Infection!

Should I transfer to a facility that has Hyperbaric oxygen (HBO)?

Page 27: Shapiro Handout

Evidence based survey of HBO in treating NSTIs

• There are no prospective randomized controlled studies on this subject

• All information on NSTI treatment is based on retrospective case reviews

• Because of the rarity, varied eitiologies and presentations of this disease, there will likely never be a gold-standard study

Page 28: Shapiro Handout

Role of HBO in NSTI

• Currently not sufficient data to mandate transfer of patient to HBO containing facility…do not delay surgical intervention!

• If available HBO should be considered for possible benefits on mortality and improved wound closure

Page 29: Shapiro Handout

The more things change…