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Anaerobic and Necrotizing Infections

para>Antibiotics given before cultures are obtained may alter lab findings

  • Plain radiographs may show SC air (rare; specific but not sensitive).
  • CT may reveal soft tissue swelling and gas in tissues.
  • MRI is useful for soft tissue imaging.
  • Imaging should not delay prompt surgical therapy.

Test Interpretation

  • Frozen-section biopsy of the fascia is diagnostic. Do not delay treatment pending biopsy.
  • Soft tissue necrosis, with polymorphonuclear cells and vascular thrombosis

TREATMENT

GENERAL MEASURES

  • Prompt and wide surgical d ©bridement is the cornerstone of treatment.
  • Hyperbaric oxygen (HBO) is an adjunct to antibiotics and aggressive surgical d ©bridement.HBO therapy in NF is controversial, no consistent survival benefit has been demonstrated.Do not delay surgical intervention for HBO.
  • IV fluids with electrolyte repletion
  • Tetanus prophylaxis

MEDICATION

First Line

  • Precautions: Without surgical d ©bridement, antibiotics will not be effective.
  • Important: Do not delay antibiotic treatment, even if smear, cultures, and tests are negative.
  • Start with broad-spectrum antibiotics then tailor to culture results and organism sensitivities.For mixed infection: ampicillin-sulbactam or piperacillin-tazobactam plus clindamycin plus ciprofloxacin; OR carbapenem; OR cefotaxime plus metronidazole or clindamycin; for PCN allergy: clindamycin or metronidazole with an aminoglycoside or fluoroquinolone
  • Clindamycin 600 mg QID IV works synergistically with penicillin 2 to 4 MU QID IV when large bacterial load is present and also binds group A streptococci toxin.For Streptococcus infection: penicillin plus clindamycinFor S. aureus infection: nafcillin 1 to 2 g q4h IV, or oxacillin 1 to 2 q4h IV, or cefazolin 1 g q8h IV; vancomycin 30 mg/kg/day in 2 divided doses IV or linezolid 600 mg q12h if concern for MRSAFor Clostridium infection: clindamycin or penicillin
  • There may be a survival benefit with IV immunoglobulin therapy (binds toxins and superantigens to suppress inflammatory mediators)
  • Unlike C. perfringens and group A β-hemolytic streptococci, Aeromonas sp. are uniformly resistant to penicillin G (but are reported to be highly sensitive to 3rd-generation cephalosporins).
  • In high-risk patients with multiple comorbidities and risk factors for NF, start with a double antibiotic regimen.

SURGERY/OTHER PROCEDURES

  • Necrotizing soft tissue infections are surgical emergencies. Take patients to the OR as soon as the diagnosis is clinically suspected or confirmed.
  • All necrotic tissue should be resected. Dissection should be carried out along all involved fascial planes. Adequate d ©bridement takes priority over tissue preservation.
  • Limb amputation may be necessary because of extensive fascial and SC soft tissue necrosis and overwhelming systemic toxicity.
  • Adequate surgical treatment is rarely accomplished with a single operation. Repeated daily d ©bridement may be necessary. D ©bridement should continue until all necrotic tissue is removed.
  • Negative-pressure suction dressing (i.e., vacuum-assisted closure dressing) may help with wound care and postoperative fluid management.
  • Reconstruction can be undertaken once all nonviable tissue has been removed and the patient is stable.

INPATIENT CONSIDERATIONS

Nursing

  • Following surgical d ©bridement, patients often require ICU-level care.
  • Close contacts of patients and health care workers do not require chemoprophylaxis with antibiotics.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

  • May require ICU-level critical care
  • Monitor for clinical signs indicating need for repeated d ©bridement.
  • As clinically indicated, may include following cultures, electrolytes, drug levels

DIET

Depends on clinical scenario

PROGNOSIS

  • Mortality for NF ranges from 10% to 20% (3)[B].
  • Mortality from necrotizing soft tissue infections is decreasing, possibly due to improved recognition and earlier delivery of more effective therapy (4)[C].
  • Increased mortality is associated with age >60 years, male, IV drug abuse, malnutrition, significant medical comorbidities (e.g., cardiac or pulmonary disease), carcinoma, and presence of bacteremia.Fournier gangrene in females may have increased risk for mortality (5)[B].
  • Independent predictors of mortality include:Admission WBC count >30,000Creatinine level >2 mg/dL within 48 hours of admissionPresence of clostridial infectionPresence of heart disease
  • Independent predictors of limb loss include:Shock (systolic pressure <90 mm Hg) on admissionClostridial infectionPresence of heart disease

COMPLICATIONS

  • Tissue and functional losses
  • Amputation
  • Septic shock
  • Death

REFERENCES

11 Lancerotto L, Tocco I, Salmaso R, et al. Necrotizing fasciitis: classification, diagnosis, and management. J Trauma Acute Care Surg. 2012;72(3):560-566.22 Kaafarani HM, King DR. Necrotizing skin and soft tissue infections. Surg Clin North Am. 2014;94(1):155-163.33 Kao LS, Lew DF, Arab SN, et al. Local variations in the epidemiology, microbiology, and outcome of necrotizing soft-tissue infections: a multicenter study. Am J Surg. 2011;202(2):139-145.44 Ustin JS, Malangoni MA. Necrotizing soft-tissue infections. Crit Care Med. 2011;39(9):2156-2162.55 Czymek R, Frank P, Limmer S, et al. Fournier's gangrene: is the female gender a risk factor? Langenbecks Arch Surg. 2010;395(2):173-180.66 Kobayashi L, Konstantinidis A, Shackelford S, et al. Necrotizing soft tissue infections: Delayed surgical treatment is associated with increased number of surgical debridements and morbidity. J Trauma. 2011;71(5):1400-1405.

ADDITIONAL READING

  • Faraklas I, Stoddard GJ, Neumayer LA, et al. Development and validation of a necrotizing soft-tissue infection mortality risk calculator using NSQIP. J Am Coll Surg. 2013;217(1):153-160.e3.
  • Kim KT, Kim YJ, Won Lee J, et al. Can necrotizing infectious fasciitis be differentiated from nonnecrotizing infectious fasciitis with MR imaging? Radiology. 2011;259(3):816-824.
  • Morgan MS. Diagnosis and management of necrotising fasciitis: a multiparametric approach. J Hosp Infect. 2010;75(4):249-257.
  • Sarani B, Strong M, Pascual J, et al. Necrotizing fasciitis: current concepts and review of the literature. J Am Coll Surg. 2009;208(2):279-288.
  • Sartelli M, Malangoni MA, May AK, et al. World Society of Emergency Surgery (WSES) guidelines for management of skin and soft tissue infections. World J Emerg Surg. 2014;9(1):57.
  • Soh CR, Pietrobon R, Freiberger JJ, et al. Hyperbaric oxygen therapy in necrotising soft tissue infections: a study of patients in the United States Nationwide Inpatient Sample. Intensive Care Med. 2012;38(7):1143-1151.
  • Wong CH, Khin LW, Heng KS, et al. The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. Crit Care Med. 2004;32(7):1535-1541.

CODES

ICD10

  • M72.6 Necrotizing fasciitis
  • L03.90 Cellulitis, unspecified
  • A48.0 Gas gangrene
  • N49.3 Fournier gangrene

ICD9

  • 728.86 Necrotizing fasciitis
  • 682.9 Cellulitis and abscess of unspecified sites
  • 040.0 Gas gangrene
  • 785.4 Gangrene

SNOMED

  • Necrotizing fasciitis (disorder)
  • cellulitis (disorder)
  • Gas gangrene (disorder)
  • Fournier's gangrene
  • anaerobic cellulitis (disorder)
  • Gangrenous disorder (disorder)
  • Infection due to anaerobic bacteria

CLINICAL PEARLS

  • Necrotizing infections are associated with potentially life-threatening rapidly progressive, widespread fascial necrosis.
  • NF may be mono- or polymicrobial.
  • Consider necrotizing soft tissue infection in patients who have pain out of proportion to the physical exam.
  • Surgical d ©bridement and antibiotic therapy are the primary treatments for necrotizing soft tissue infections.
  • A delay of >12 hours in surgical treatment is associated with an increased need for repeat surgical d ©bridements, septic shock, and acute kidney injury (6)[B].