Definitions of Skin/Soft Tissue Infections

- Cellulitis (see Cellulitis, [[Cellulitis]]): skin infection of deeper dermis and subcutaneous fat (resulting from bacterial breach of the skin) characterized by erythema, warmth, and edema without an underlying suppurative focus
- Erysipelas (see Erysipelas, [[Erysipelas]]): skin infection of upper dermis and superficial lymphatics (resulting from bacterial breach of the skin) characterized by erythema, warmth, and edema without an underlying suppurative focus
- Impetigo (see Impetigo, [[Impetigo]]): infection of superficial layers of the epidermis
- Necrotizing Soft Tissue Infection: all of these are characterized by fulminant tissue destruction, systemic toxicity, and high mortality rates
- Necrotizing Cellulitis
- Meleney’s Synergistic Gangrene
- Clostridial Anaerobic Necrotizing Cellulitis
- Non-Clostridial Anaerobic Necrotizing Cellulitis
- Necrotizing Fasciitis: deep-seated infection of subcutaneous tissue (involving fascia and fat), which may spare the skin
- Type I (Mixed Aerobic and Anaerobic Infection)
- Type II (Monomicrobial Infection)
- Necrotizing Myositis (Spontaneous Gangrenous Myositis): xxx
- Necrotizing Cellulitis
- Clostridial Myonecrosis (Gas Gangrene) (see Clostridial Myonecrosis, [[Clostridial Myonecrosis]]): life-threatening muscle infection which develops either contiguously from a site of trauma or via hematogenous spread from the gastrointestinal tract to the muscle
- Furuncle (Boil) (see Skin Abscess, [[Skin Abscess]]: infection of hair follicle where purulent material extends through the dermis into the subcutaneous tissue, forming a small abscess
- Carbuncle (see Skin Abscess, [[Skin Abscess]]: coalescence of several inflamed follicles into a single inflammatory mass with purulent drainage from multiple follicles
- Skin Abscess (see Skin Abscess, [[Skin Abscess]]): collection of pus within dermis and deeper skin tissues
History
- Civil War: first description of necrotizing fasciitis by the Confederate Army surgeon, Joseph Jones
- 1883: Fournier described necrotizing fasciitis in the perineal and genital region
- 1952: Wilson first used the term “necrotizing fasciitis”
Diagnosis
Laboratory Risk Indicator for Necrotizing Soft Tissue Infection (LRINEC)
- C-Reactive Protein (CRP) (mg/L)
- CRP < 150 -> 0 points
- CRP ≥ 150 -> 4 points
- WBC
- WBC < 15 -> 0 points
- WBC 15-25 -> 1 point
- WBC >25 -> 2 points
- Hemoglobin (g/dL)
- Hb >13.6 -> 0 points
- Hb 11-13.5 -> 1 points
- Hb < 10.9 -> 2 points
- Sodium (mmol/L)
- Na ≥ 135 -> 0 points
- Na < 135 -> 2 points
- Creatinine (mg/dL)
- Cr ≤ 1.6 -> 0 points
- Cr >1.6 -> 2 points
- Glucose (mg/dL)
- Glc ≤ 180 -> 0 points
- Glc >180 -> 1 point
- LRINEC Score -> Probability of Necrotizing Fasciitis
- Low Risk: <5 points -> <50% probability of necrotizing fasciitis
- Intermediate Risk: 6-7 points -> 50-75% probability of necrotizing fasciitis
- High Risk: >8 points -> >75% probability of necrotizing fasciitis
Complete Blood Count (CBC) (see Complete Blood Count, [[Complete Blood Count]])
- Leukocytosis (see Leukocytosis, [[Leukocytosis]])
X-Rays
- May Reveal Gas in Soft Tissues: although these are of limited utility in cases where gas is unlikely to be found (ie: those due to Strep and MRSA) and may delay the necessary surgical management
Computed Tomography (CT)
- Useful to Image Soft Tissues
Magnetic Resonance Imaging (MRI)
- Useful to Differentiate Fasciitis from Cellulitis
- Gas in deep tissues is more common with Clostridium and mixed aerobic-anerobic cases (but is unusual in Strep and MRSA-associated cases)
Ultrasound with Aspiration of Perifascial Fluid Collections
- May Be Useful
- “Dishwater” appearance of fluid
Finger Test
- Procedure: 2 cm incision down to deep fascia (with local anesthesia)
- Lack of bleeding from incision or “dishwater” fluid expressed -> suggest necrotizing fasciitis
- If the tissues at level of the deep fascia dissect with minimal resistance, the finger test is positive -> suggests necrotizing fasciitis
Tissue Biopsy with Rapid Frozen Section Analysis
- May Demonstrate Obliterative Vasculitis of Subcutaneous Vessels, Acute Inflammation, and Subcutaneous Tissue Necrosis
Clinical Pattern-Necrotizing Cellulitis
Meleney’s Synergistic Gangrene
- Epidemiology
- Rare
- Occurs in Postoperative Patients
- Microbiology
- Combined Staphylococcus Aureus + Microaerophilic Streptococci (see Staphylococcus Aureus, [[Staphylococcus Aureus]] and Streptococcus, [[Streptococcus]]): involves a synergistic interaction between these organisms
- Physiology
- Confined to the Superficial Fascia
- Clinical
- Slowly Expanding Indolent Ulceration Confined to Superficial Fascia
Clostridial Anaerobic Necrotizing Cellulitis
- Epidemiology
- XXXX
- Microbiology
- Clostridium Perfringens (see Clostridium Perfringens, [[Clostridium Perfringens]]): most common etiology
- Clostridium Septicum (see Clostridium Septicum, [[Clostridium Septicum]]): less frequent etiology
- Physiology
- Portal of Entry
- Spread of Infection from Bowel to Perineum/Abdominal Wall/Lower Extremities
- Surgical Contamination
- Trauma
- Portal of Entry
- Clinical
- Gradual Onset with Subsequent Rapid Spread
- Pain/Swelling/Systemic Toxicity are Not Prominent Features
- Milder Clinical Illness Distinguishes this from True Gas Gangrene
- Thin, Dark, Foul-Smelling Wound Drainage: may contain fat globules
- Tissue Gas Formation (see Skin Crepitus, [[Skin Crepitus]])
- Sparing of Fascia and Deep Muscle
- Treatment
- Surgical Exploration/Debridement is Required to Distinguish Anaerobic Cellulitis from Fasciitis and Myonecrosis
Non-Clostridial Anaerobic Necrotizing Cellulitis
- Epidemiology
- Risk Factors
- Diabetes Mellitus (DM) (see Diabetes Mellitus, [[Diabetes Mellitus]])
- Risk Factors
- Microbiology: non-spore forming anaerobic bacteria with/without facultative organisms
- Non-Spore Forming Anaerobic Bacteria
- Bacteroides (see Bacteroides, [[Bacteroides]])
- Peptostreptococcus (see Peptostreptococcus, [[Peptostreptococcus]])
- Facultative Bacteria
- Coliforms/Gram-Negative Rods
- Staphylococcus (see Staphylococcus, [[Staphylococcus]])
- Streptococcus (see Streptococcus, [[Streptococcus]])
- Non-Spore Forming Anaerobic Bacteria
- Clinical
- Gradual Onset with Subsequent Rapid Spread
- Pain/Swelling/Systemic Toxicity are Not Prominent Features
- Milder Clinical Illness Distinguishes this from True Gas Gangrene
- Thin, Dark, Foul-Smelling Wound Drainage: may contain fat globules
- Tissue Gas Formation (see Skin Crepitus, [[Skin Crepitus]])
- Sparing of Fascia and Deep Muscle
Clinical Pattern-Necrotizing Fasciitis
Type I Necrotizing Fasciitis
Epidemiology
- Type I is the Most Common Type of Necrotizing Fasciitis
- Risk Factors
- Diabetes Mellitus (DM) (see Diabetes Mellitus, [[Diabetes Mellitus]]): most commonly involving the lower extremity
- Immunocompromised State
- Obesity (see Obesity, [[Obesity]])
- Peripheral Arterial Disease (PAD) (see Bacteroides Fragilis, [[Bacteroides Fragilis]])
- Clostridium Species (see Clostridium, [[Clostridium]])
- Clostridium Septicum (see Clostridium Septicum, [[Clostridium Septicum]])
- Enterococcus (see Enterococcus, [[Enterococcus]])
- Escherichia Coli (see Escherichia Coli, [[Escherichia Coli]])
- Peptostreptococcus (see Peptostreptococcus, [[Peptostreptococcus]])
- Porphyromonas (see Porphyromonas, [[Porphyromonas]])
- Prevotella (see Prevotella, [[Prevotella]])
- Staphylococcus Aureus (see Staphylococcus Aureus, [[Staphylococcus Aureus]])
- Streptococcus (see Streptococcus, [[Streptococcus]])
- Cervical Necrotizing Fasciitis of the Neck
- Microbiology
- Most Cases are Due to Mixed Aerobic and Anaerobic Infection
- Portal of Entry
- Breach in the Oropharyngeal Mucous Membrane Due to Surgery, Instrumentation, or Odontogenic Infection
- Clinical
- Fasciitis May Spread to Face, Lower Neck, or Mediastinum
- Microbiology
- Fournier’s Gangrene (see Fournier’s Gangrene , [[Fourniers Gangrene]])
- Sex
- Most Common in Older Males
- Female Cases May Occur in the Setting of Diabetes Mellitus
- Risk Factors
- Diabetes Mellitus (DM) (see Diabetes Mellitus, [[Diabetes Mellitus]])
- Penetating Abdominal Injury
- Peripheral Arterial Disease (PVD) (see Peripheral Arterial Disease, [[Peripheral Arterial Disease]])
- Surgery
- Physiology
- Breach in Gastrointestinal/Genitourinary Tract or Labia: by diverticulum, malignancy, hemorrhoid, anal fissure/perianal abscess, Bartholin abscess, episiotomy, , vulvovaginal infection, decubitus ulcer, or urethral tear
- Once Infection Reaches the Deep Fascia of Perineum, Rapid Spread Along Fascial Planes, Through Venous Channels and Lymphatics to Involve the Anterior Abdominal Wall/Gluteal Muscles/Scrotum/Penis
- Clinical
- Fever (see Fever, [[Fever]]): early finding
- Abrupt Onset of Severe Pain Over Skin and Underlying Muscle: sensitive, early finding that may precede development of fever (Chest, 2005) [MEDLINE]
- Crepitus (see Skin Crepitus, [[Skin Crepitus]]): may occur
- Penile Edema
- Scrotal Swelling
- Vesicular Skin Lesions (see Vesicular-Bullous-Pustular Skin Lesions, [[Vesicular-Bullous-Pustular Skin Lesions]]): may occur
- Extension into Perineum/Abdominal Wall/Lower Extremities (with skin findings, as noted for other presentations)
- Myositis (Occurs Concomitantly in 20-40% of Cases): elevated CK
- Septic Shock/Multiorgan Failure (see Sepsis, [[Sepsis]])
- Treatment: early aggressive drainage/debridement (may require cystostomy, colostomy, or orchiectomy)
- Sex
- Lower Extremity Necrotizing Fasciitis
- Epidemiology
- Most Common Site in Cases Associated with Diabetes Mellitus and Peripheral Arterial Disease
- Epidemiology
- Ludwig’s Angina (see Ludwig’s Angina, [[Ludwigs Angina]])
- Clinical
- XXXX
- Clinical
- Surgical Wound Infection
- Clinical
- Copious Drainage
- Dusky, Friable Subcutaneous Tissue with Pale, Devitalized Fascia
- Clinical
- Neonatal Necrotizing Fasciitis
- Clinical
- Usually Associated with Omphalitis (Most Commonly), Balanitis, Mammitis, or Fetal Monitoring
- Most Commonly Involves Abdomen/Perineum
- Clinical
- Type II Necrotizing Fasciitis is Usually Monomicrobial
- Portal of Entry
- Breach in the Oropharyngeal Mucous Membrane Due to Surgery, Instrumentation, or Odontogenic Infection
- Microbiology
- Streptococcus Pyogenes (Group A Streptococcus) (see Streptococcus Pyogenes, [[Streptococcus Pyogenes]])
- Clinical
- Fasciitis May Spread to Face, Lower Neck, or Mediastinum
- Epidemiology
- XXX
- Risk Factors
- Diabetes Mellitus (DM) (see Diabetes Mellitus, [[Diabetes Mellitus]])
- Insect Bite
- Intravenous Drug Abuse (IVDA) with Subcutaneous Injection of Black Tar Heroin (see Intravenous Drug Abuse, [[Intravenous Drug Abuse]])
- Peripheral Arterial Disease (PAD) (see MEDLINE]
- Fever (see Fever, [[Fever]]): may be absent early
- Brawny Edema: may extend beyond the area of erythema
- Subcutaneous tissues may feel wooden/hardened with loss of feeling of fascial planes and muscle groups
- Vesicular Skin Lesions: may occur
- Crepitus (see Skin Crepitus, [[Skin Crepitus]]): may occur
- Later Findings
- Dark Red Induration of Skin
- Bullae Filled with Blue/Purple Fluid
- Late Findings
- Friable Bluish/Maroon/Black Skin (due to extensive thrombosis of blood vessels in dermal papillae)
- Brownish/Gray Skin (due to extension into the deep fascia)
- Septic Shock/Multiorgan Failure (see Sepsis, [[Sepsis]])
Streptococcal Gangrene
- Epidemiology
- Age: can occur in any age group
- Most Cases are Community-Acquired
- Most Cases Occur in Patients without Co-Morbid Conditions (in Contrast to Type I Necrotizing Fasciitis Cases)
- Of the 3.5 Million Cases of Invasive Streptococcus Pyogenes Cases Per Year in th US, Necrotizing Fasciitis Accounts for Approximately 6% of These Cases
- Incidence: appears to be increasing since 1985
- Risk Factors
- Burns (see Burns, [[Burns]])
- Childbirth
- Diabetes Mellitus (DM) (see Diabetes Mellitus, [[Diabetes Mellitus]])
- Exposure to a Known Case
- Intravenous Drug Abuse (IVDA) (see Intravenous Drug Abuse, [[Intravenous Drug Abuse]])
- Nonsteroidal Anti-Inflammatory Drugs (NSAID’s) (see Nonsteroidal Anti-Inflammatory Drug, [[Nonsteroidal Anti-Inflammatory Drug]]): possible predisposing factor
- Peripheral Arterial Disease (PAD) (see Varicella-Zoster Virus, [[Varicella-Zoster Virus]])
- Microbiology
- Streptococcus Pyogenes (Group A Strep) (see Streptococcus Pyogenes, [[Streptococcus Pyogenes]]): most common Streptococcus species associated with necrotizing fasciitis
- Concomitant Streptococcus Pyogenes and Staphylococcus Infection May Occur in Some Cases
- Streptococcus Agalactiae (Group B Strep) (see Streptococcus Agalactiae, [[Streptococcus Agalactiae]]): reported cases
- Streptococcus Pyogenes (Group A Strep) (see Streptococcus Pyogenes, [[Streptococcus Pyogenes]]): most common Streptococcus species associated with necrotizing fasciitis
- Physiology
- Cases with Defined Portal of Entry: 50% of cases
- Infection Usually Enters Through Penetrating Trauma or Cutaneous Site of Infection
- Early Findings: signs of superficial skin infection
- Later Findings: purple (violaceous) bullae, skin sloughing, etc
- Once Infection Reaches the Deep Fascia, it Rapidly Spreads Along Fascial Planes, Through Venous Channels and Lymphatics
- Cases with No Defined Portal of Entry: 50% of cases
- Asymptomatic/Symptomatic Pharyngitis Likely Results in Subsequent Hematogenous Dissemination to a Site of Non-Penetrating Minor Trauma (Such as a Bruise or Muscle Strain)
- Early Findings: severe pain, fever (without signs of superficial skin infection)
- Later Findings: purple (violaceous) bullae, skin sloughing, etc
- Cases with Defined Portal of Entry: 50% of cases
- Clinical
- Approximately 66% of Cases Occur in the Lower Extremities
- Early Findings
- Severe Pain Over Skin and Underlying Muscle: sensitive, early finding that may precede development of fever and other constitutional symptoms [MEDLINE]
- Crepitus (see Skin Crepitus, [[Skin Crepitus]]): may occur
- Fever: may be absent early
- Brawny Edema: may extend beyond the area of erythema
- Subcutaneous tissues may feel wooden/hardened with loss of feeling of fascial planes and muscle groups
- Vesicular Skin Lesions: may occur
- Later Findings
- Dark Red Induration of Skin
- Bullae Filled with Blue/Purple Fluid
- Late Findings
- Friable Bluish/Maroon/Black Skin (due to extensive thrombosis of blood vessels in dermal papillae)
- Brownish/Gray Skin (due to extension into the deep fascia)
- Septic Shock/Multiorgan Failure (see Sepsis, [[Sepsis]])
Anaerobic Streptococcus (Peptostreptococcus) (see Peptostreptococcus, [[Peptostreptococcus]])
- Epidemiology
- XXXX
Aeromonas Hydrophila-Associated Necrotizing Fasciitis (see Aeromonas Hydrophila, [[Aeromonas Hydrophila]])
- Epidemiology
- Necrotizing Soft Tissue Infection is Associated with Traumatic Injuries in Freshwater
- Clinical
- XXXX
Clostridium Novyii-Associated Necrotizing Fasciitis (see Clostridium Novyii, [[Clostridium Novyii]])
- Epidemiology
- XXXX
- Risk Factor
- Intravenous Drug Abuse (IVDA) with Subcutaneous Injection of Black Tar Heroin (see Intravenous Drug Abuse, [[Intravenous Drug Abuse]])
- Portal of Entry
- Breach of Skin/Mucosa
- Clinical
- Gas Gangrene
Clostridium Sordellii-Associated Necrotizing Fasciitis (see Clostridium Sordellii, [[Clostridium Sordellii]]
- Epidemiology
- XXXX
- Risk Factor
- Intravenous Drug Abuse (IVDA) with Subcutaneous Injection of Black Tar Heroin (see Intravenous Drug Abuse, [[Intravenous Drug Abuse]])
- Portal of Entry
- Breach of Skin/Mucosa
- Clinical
- Necrotizing Fasciitis
Vibrio Vulnificus-Associated Necrotizing Fasciitis (see Vibrio Vulnificus, [[Vibrio Vulnificus]])
- Epidemiology
- Necrotizing Soft Tissue Infection is Associated with Traumatic Injuries in Seawater
- Necrotizing Soft Tissue Infection in Patients with Cirrhosis is Associated with Ingestion of Contaminated Oysters
- Portal of Entry
- Breach of Skin/Mucosa
- Clinical
- XXXX
Synergistic Necrotizing Cellulitis
- Epidemiology
- Risk Factors
- Diabetes Mellitus (DM) (see Diabetes Mellitus, [[Diabetes Mellitus]])
- Risk Factors
- Clinical
- Variant of Necrotizing Fasciitis Which Involves the Skin/Muscle/Fat/Fascia
- Usually Involves the Lower Extremities or Perineum
Clinical Pattern-Necrotizing Myositis (Spontaneous Gangrenous Myositis)
Epidemiology
- xxxx
- XXXX
XXX
Microbiology
- xxx
Clinical
- xxxx
XXXX
Gallery
Example of Streptococcus Pyogenes Necrotizing Cellulitis
- 62 y/o Female with Left Forearm Cellulitis After Superficial Wound
Example of Type I Necrotizing Fasciitis
- 36 y/o Diabetic Caucasian Male (with HbA1C 13%) Who Presented with Ulcerating Left Foot Skin Lesions
- Patient Underwent Immediate Surgical Incision and Drainage of the Left Foot/Distal Left Leg and Left Great Toe Amputation
- 12 hrs Later, He Developed Progressive Gangrene Adjacent to the Surgical Field (Picture Below), Requiring Repeat Surgical Debridement with Left Below the Knee Amputation
- Blood Cultures were Positive for Streptococcus Agalactiae (Group B Streptococcus)
- Wound Cultures were Positive for Escherchia Coli + Streptococcus Agalactiae (Group B Streptococcus)
Treatment
Antibiotics
- Clindamycin (see Clindamycin, [[Clindamycin]])
- Unlike penicillin, the efficacy of clindamycin is not affected by the inoculum size or stage of bacterial growth
- Clindamycin suppresses bacterial toxin synthesis
- Subinhibitory concentrations of clindamycin facilitate Strep Pyogenes phagocytosis
- Clindamycin decreases the synthesis of penicillin-binding protein, which, in addition to being a target for penicillin, is also an enzyme involved in cell wall synthesis and degradation
- Clindamycin has a longer postantibiotic effect than β-lactams (such as penicillin)
- Clindamycin suppresses LPS-induced mononuclear synthesis of tumor necrosis factor-α
- Vancomycin (see Vancomycin, [[Vancomycin]]): or comparable agent, to cover for possible MRSA
- Gram-Negative Coverage: also useful
Intravenous Immunoglobulin (IVIG) (see Intravenous Immunoglobulin, [[Intravenous Immunoglobulin]])
- Reported in the Treatment of Streptococcal Toxic Shock Syndrome (see Streptococcal Toxic Shock Syndrome, [[Streptococcal Toxic Shock Syndrome]]): may have a role in Streptococcus-associated necrotizing faasciitis cases (although this is not an FDA-approved indication)
Prompt Surgical Debridement Down to Fascia with Wide Excision
- Early surgical intervention has been demonstrated to improve mortality and decrease tissue loss (amputation, etc).
- Delayed surgical intervention is associated with increased risk of death [MEDLINE]
- Average latency from admission to surgery in survivors: 25 hrs
- Average latency from admission to surgery in non-survivors: 90 hrs
- Delayed surgical intervention is associated with increased risk of death [MEDLINE]
Hyperbaric Oxygen (HBO) (see Hyperbaric Oxygen, [[Hyperbaric Oxygen]])
- Unclear Benefit in Necrotizing Fasciitis
Treatment of Septic Shock (see Sepsis, [[Sepsis]])
- Standard Measures
Prognosis
- Death: may occur if necrotizing fasciitis is not promptly recognized and treated
References
- Determinants of mortality for necrotizing soft-tissue infections. Ann Surg. May 1995;221(5):558-63 [MEDLINE]
- Necrotizing fasciitis. Chest. Jul 1996;110:219-29 [MEDLINE]
- The changing spectrum. Dermatol Clin. Apr 1997;15(2):213-20 [MEDLINE]
- Group B streptococcal necrotizing fasciitis and streptococcal toxic shock-like syndrome in adults. Arch Intern Med. 1998 Aug 10-24;158(15):1704-8 [MEDLINE]
- A 46-year-old man with excruciating shoulder pain. Chest. Mar 2005;127(3):1039-44 [MEDLINE]
- Necrotizing soft-tissue infection: diagnosis and management. Clin Infect Dis. 2007;44(5):705 [MEDLINE]
- Group B streptococcal necrotizing fasciitis from a decubitus ulcer. Int J Emerg Med. 2010 Dec; 3(4): 519–520 [MEDLINE]
- Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2014 Jul 15;59(2):e10-52. doi: 10.1093/cid/ciu444 [MEDLINE]
- Necrotising soft tissue infection in a UK metropolitan population. Ann R Coll Surg Engl. 2015 Jan;97(1):46-51. doi: 10.1308/003588414X14055925058553 [MEDLINE]