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Anaerobic & Necrotizing Infections

Description of Medical Condition

Gangrene is local death of soft tissues due to disease or injury and is associated with loss of blood supply. Anaerobic and necrotizing infections may be associated with gas.

Anaerobic & Necrotizing Infections

System(s) affected: Skin/Exocrine, Cardiovascular

Genetics: N/A

Incidence/Prevalence in USA: Rare

Predominant age: Any

Predominant sex: Male = Female

Anaerobic & Necrotizing Infections

Medical Symptoms and Signs of Disease

  • Local pain
  • Foul odor
  • Abnormally dark skin and tissues under skin (dark green to black)
  • Crepitation (gas)
  • Fever
  • Rapid pulse
  • Fulminant course leading to death without treatment

What Causes Disease?

  • Local injury
  • Superimposed infection (surface or deep; local or distant)
  • Carcinoma of large intestine
  • Hematologic malignancies
  • Severe neutropenia, related or not related to chemotherapy
  • Burns
  • Liposuction

Risk Factors

  • Poor blood supply (arteriosclerosis)
  • Old age
  • Trauma
  • Diabetes mellitus
  • Malnutrition
  • Immune suppression
  • Chickenpox

Diagnosis of Disease

Differential Diagnosis

  • Deep infections with muscle involvement
    • Gas gangrene
    • Gas gangrene resulting from soft tissue trauma with multiple aerobic and anaerobic organisms; synergistic necrotizing sepsis, synergistic necrotizing cellulitis; clostridial myositis; clostridial myonecrosis
    • Abdominal wall gas gangrene; postoperative clostridial sepsis of the abdominal wall; clostridial myonecrosis of the abdominal wall
    • Nontraumatic, metastatic, clostridial myonecrosis: metastatic clostridial myositis; metastatic gas gangrene; gas gangrene without a visible wound: spontaneous gas gangrene
    • Uterine clostridial infections
    • Gas gangrene of the heart
    • Gas gangrene of the brain
    • Streptococcal myositis: anaerobic streptococcal myonecrosis; anaerobic streptococcal myositis
    • Infected vascular gas gangrene; non-clostridial gas gangrene; non-clostridial myositis
  • Superficial infections — with or without abscess
    • Hemolytic streptococcal gangrene
    • Acute, infectious staphylococcal gangrene
    • Anaerobic cellulitis; crepitant phlegmon; clostridial cellulitis

Onecrotizing fasciitis due to multiple aerobic and anaerobic organisms; synergistic gangrene; non-clostridial anaerobic cellulitis; anaerobic cutaneous gangrene; perineal phlegmon; Fournier gangrene. (Note: If there is extension to the tissues of the abdominal wall below the deep fascia, such as the anterior sheath of the rectus muscle, perineal phlegmon or Fournier gangrene is a synergistic necrotizing sepsis rather than just a necrotizing fasciitis. These are similar infections but are in different locations.)

Onecrotizing fasciitis due to group A streptococcus (there may be very rapid extension to structures deep to the deep fascia)

  • Panophthalmitis
  • Simple clostridial contamination of wounds
  • Infiltration or injection or aspiration of gas into wounds
    • Wounds with gas not produced by bacteria
    • Injection of gas into wounds
    • Therapy (e.g., hydrogen peroxide)
    • Pranksters’jokes
    • Malingerers
    • Psychiatric problems
    • Aspiration and dissemination of air into wounds by muscular activity
    • Subcutaneous emphysema related to air leak syndrome or trauma
  • Gas in tissues after industrial accidents
    • Magnesiogenous pneumogranuloma
  • Gas in tissues after injections of chemicals
    • Injection of drugs
    • Accidental injection of a foreign agent, such as benzene
  • Gas in tissues after laparoscopic examination and treatment


  • With severe gangrene, studies will reveal anemia and leukocytosis
  • Gram smears for many possible organisms
  • Daily serum creatine kinase determinations

Drugs that may alter lab results: Antibiotics prior to culture

Disorders that may alter lab results: N/A

Pathological Findings

  • Necrosis of tissues with foul odor
  • Sometimes, gas in tissues
  • Microorganisms

Special Tests

Cultures and sensitivity tests for microorganisms reported to produce gas in human tissues: Gram-positive anaerobes: Cocci — Peptostreptococcus (anaerobic Streptococcus) (usually with group A Streptococcus [Streptococcus pyogenes, beta-hemolytic Streptococcus] or Staphylococcus aureus) Gram-positive anaerobes: Bacilli — Clostridium pertringens and other clostridia Gram-negative aerobes: Bacilli — Escherichia coli. Klebsiella pneumoniae, Enterobacter species, Proteus species (all usually in mixed infections)

Gram-negative anaerobes: Bacilli — Bacteroides fragilis (usually with other gram-negative bacilli)


Plain radiographs, gas in tissues; with MRI, edema

Diagnostic Procedures

IMMEDIATE SURGICAL INTERVENTION with longitudinal incisions of skin, superficial fascia, deep fascia, and muscles to look for necrotic tissue and/or foreign bodies and with removal of necrotic tissue or foreign bodies. Daily repetition if indicated. Repeated physical examinations for another, similar, focal infection.

Treatment (Medical Therapy)

Appropriate Health Care

Hospital inpatient

General Measures

  • Infectious disease consultation if available
  • Intravenous fluids with glucose, electrolytes, blood, vitamins
  • Daily CBC and electrolytes in acute phase
  • Prophylaxis for tetanus
  • Hyperbaric oxygen: unclear therapeutic value; no delay of surgical intervention for hyperbaric oxygen therapy

Surgical Measures

  • Surgical intervention for diagnosis and debridement ot necrotic tissues; possibly daily
  • Re-operation if possibility of spreading or unrecognized necrosis and/or foreign bodies (with abnormal daily CPK determination)
  • Surgical repair for loss of skin and subcutaneous tissues




By mouth, as tolerated

Patient Education


Medications (Drugs, Medicines)

Drug(s) of Choice

Initially broad spectrum, antibiotic regimen; then specific antibiotic regime as determined by stained smears, cultures, and sensitivity tests with particular reference to the sensitivities of the hospital where the patient is being treated (although anaerobic organisms are difficult to culture and identify). Dosage will vary according to clinical circumstances; refer to manufacturer’s literature and suggestions of infectious disease consultant, mportant: don’t delay treatment if smear, cultures and tests negative.

Gram stain and presumptive organism

  • Gram stain Presumed organism + cocci Streptococcus + cocci Staph. aureus + bacilli Clostridium spp – bacilli Bacteroides spp – bacilli Coliforms – Gram-positive cocci: penicillin G, nafcillin (Unipen).
  • clindamycin (Cleocin), metronidazole (Flagyl), or cephalosporins
  • Gram-positive bacilli: penicillin G, clindamycin.

Metronidazole or cephalosporins

  • Gram-negative bacilli (Bacteroides): clindamycin, metronidazole, cefoxitin (Mefoxin) [many B. fragilis are resistant], ticarcillin (ticar) or mezlocillin (Mezlin)
  • Gram-negative bacilli (Coliforms): gentamicin

(Garamycin), tobramycin (Nebcin), amikacin (Amikin).

Cephalosporins, ampicillin, mezlocillin, or ticarcillin

Intravenous calcium gluconate if extensive fat necrosis

Contraindications: Sensitivity to drugs


  • Sedatives and analgesics (both before and after exploratory and therapeutic operations) may make recognition of spreading gangrene more difficult
  • Repeated gram smears, culture and sensitivity tests for the best antibiotic(s)

Significant possible interactions: See manufacturer’s profile of each drug.

Alternative Drugs

As above

Patient Monitoring

  • Diligence required to recognize spreading gangrene
  • Monitor effective blood levels of prescribed antibiotics
  • Electrolytes
  • Nutrition
  • CPK determinations daily for myonecrosis
  • Progress notes in charts daily or as often as every 4 hours

Prevention / Avoidance

  • Avoidance of trauma
  • Good care of skin
  • Avoidance of tight orthopedic casts

Possible Complications

  • Tissue and functional losses
  • Amputation
  • Death

Expected Course / Prognosis

  • Fair if early diagnosis and treatment, and if gangrene arrested at an early stage
  • Fatal without treatment and possibly with treatment
  • Fair if large intestine disease is recognized and removed immediately or if hematologic malignancy is recognized and treated immediately


Associated Conditions

  • Diabetes mellitus with impaired blood flow
  • Altered immunocompetence: Depressed immuno-competence may require an alteration of treatment, especially with tumor treatments

Age-Related Factors

Pediatric: N/A

Geriatric: Diseases of the aged with debility and poor blood supply


Treatment as for nonpregnant, but consider the pregnancy

International Classification of Diseases

785.4 Gangrene

040.0 Gas gangrene

136.9 Unspecified infectious and parasitic diseases

682.9 Cellulitis and abscess at unspecified site

See Also


Other Notes

Group A Streptococcus: “flesh eating bacterium”


CBC = complete blood count

MRI = magnetic resonance imaging

CPK = serum creatinine phosphokinase

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