153: Necrotizing Fasciitis Flashcards
1
Q
What characterizes necrotizing fasciitis?
A
Necrotizing fasciitis is characterized by rapid progression of infection, spreading along the fascial plane, leading to progressive necrosis and high mortality rates if not diagnosed and managed promptly.
2
Q
What are the common predisposing comorbidities associated with necrotizing fasciitis?
A
Common predisposing comorbidities include diabetes, cardiovascular disease, IV drug abuse, peripheral vascular disease, venous stasis, obesity, smoking, alcohol abuse, cirrhosis, malignancy, corticosteroid use, and chronic kidney disease.
3
Q
What is the typical source of bacterial introduction in necrotizing fasciitis cases?
A
The majority of necrotizing fasciitis cases are community acquired via bacterial introduction through a break in the skin. In some cases, the site of bacterial introduction is never identified.
4
Q
What are the clinical scenarios where polymicrobial infections are particularly high in necrotizing fasciitis?
A
Polymicrobial infections are particularly high in bowel-associated infections, decubitus ulcers, IV drug users, and spread from genital sites.
5
Q
What is the most likely source of infection for a patient with necrotizing fasciitis and a history of recent abdominal surgery?
A
The most likely source of infection is bowel-associated, such as a perianal abscess or penetrating abdominal trauma.
6
Q
How does corticosteroid use predispose to necrotizing fasciitis?
A
Corticosteroid use suppresses the immune system, increasing susceptibility to infections like necrotizing fasciitis.
7
Q
What is the most likely site of infection for a patient with necrotizing fasciitis and a history of recent episiotomy?
A
The most likely site of infection is along the uterus or at the episiotomy site.
8
Q
How does alcohol abuse predispose to necrotizing fasciitis?
A
Alcohol abuse impairs immune function and liver function, increasing susceptibility to infections like necrotizing fasciitis.
9
Q
How does venous stasis predispose to necrotizing fasciitis?
A
Venous stasis leads to poor circulation and tissue hypoxia, creating an environment conducive to infection.
10
Q
How does smoking predispose to necrotizing fasciitis?
A
Smoking impairs vascular function and immune response, increasing susceptibility to infections like necrotizing fasciitis.
11
Q
How does malignancy predispose to necrotizing fasciitis?
A
Malignancy can lead to immunosuppression and tissue breakdown, increasing susceptibility to infections like necrotizing fasciitis.
12
Q
How does chronic kidney disease predispose to necrotizing fasciitis?
A
Chronic kidney disease impairs immune function and wound healing, increasing susceptibility to infections like necrotizing fasciitis.
13
Q
How does cirrhosis predispose to necrotizing fasciitis?
A
Cirrhosis impairs immune function and liver detoxification, increasing susceptibility to infections like necrotizing fasciitis.
14
Q
How does obesity predispose to necrotizing fasciitis?
A
Obesity is associated with poor circulation and immune dysfunction, increasing susceptibility to infections like necrotizing fasciitis.
15
Q
How does peripheral vascular disease predispose to necrotizing fasciitis?
A
Peripheral vascular disease leads to poor circulation and tissue hypoxia, creating an environment conducive to infection.
16
Q
How does diabetes predispose to necrotizing fasciitis?
A
Diabetes impairs immune function and wound healing, increasing susceptibility to infections like necrotizing fasciitis.
17
Q
How does cardiovascular disease predispose to necrotizing fasciitis?
A
Cardiovascular disease impairs circulation and tissue oxygenation, increasing susceptibility to infections like necrotizing fasciitis.
18
Q
How does IV drug use predispose to necrotizing fasciitis?
A
IV drug use introduces pathogens directly into the bloodstream or tissues, increasing the risk of infections like necrotizing fasciitis.
19
Q
What was the average number of admissions for necrotizing soft-tissue infections in the United States from 1998 to 2010?
A
The average was between 3800 to 5800 admissions annually.
20
Q
What was the prevalence of pediatric necrotizing fasciitis between 2010 and 2015?
A
It was 0.8 per 1 million patient-years.
21
Q
What role do bacterial enzymes play in necrotizing fasciitis?
A
Bacterial enzymes assist in tissue breakdown and rapid progression of the disease.
22
Q
What is the significance of polymicrobial infections in necrotizing fasciitis?
A
They are often polymicrobial with up to 5 pathogens identified in many cases.
23
Q
What are the early cutaneous features of necrotizing fasciitis?
A
Early features include erythema, pain, and surrounding edema that mimic classic cellulitis.
24
Q
What systemic symptoms may arise as necrotizing fasciitis progresses?
A
Early complaints include malaise, fever, nausea, and vomiting. As the condition worsens, patients may experience tachycardia, disorientation, and lethargy.
25
What are the four major subtypes of necrotizing fasciitis based on microbial pathogens?
Type I: Polymicrobial infections; Type II: Monomicrobial infections; Type III: Infections caused by Vibrio spp.; Synergistic Necrotizing Cellulitis: Type I with necrosis extending to muscle.
26
What is Fournier Gangrene?
Fournier Gangrene is localized to the genitalia, perineum, anus, and occasionally the skin of the lower abdomen.
27
What is the common age range for patients presenting with Fournier Gangrene?
Generally between 50 to 60 years old.
28
What are the stages of cervical and craniofacial necrotizing fasciitis?
Stage 1: Tenderness, erythema, swelling, and heat; Stage 2: Blistering and bullae; Stage 3: Crepitus, anesthesia, and skin necrosis.
29
What is the significance of the progression from severe pain to anesthesia in necrotizing fasciitis?
The progression indicates nerve damage due to tissue necrosis, a hallmark of advanced necrotizing fasciitis.
30
What is the most common isolate in community-acquired necrotizing soft-tissue infections?
Streptococcus pyogenes.
31
What are the early cutaneous features of necrotizing fasciitis?
Early cutaneous features include erythema, pain, and surrounding edema that mimic classic cellulitis.
32
How do the cutaneous features of necrotizing fasciitis progress as the disease advances?
As the disease progresses, more dramatic changes in color occur, development of bullae, and eventually gangrenous or necrotic changes of the skin and subcutaneous tissues.
33
What systemic symptoms arise as necrotizing fasciitis progresses?
Systemic symptoms include malaise, fever, nausea, and vomiting, eventually leading to tachycardia, disorientation, and lethargy.
34
What is the classification of necrotizing fasciitis based on microbial pathogens?
Necrotizing fasciitis is classified into Type I (polymicrobial infections) and Type II (monomicrobial infections).
35
What are the clinical features and staging of cervical and craniofacial necrotizing fasciitis?
Stage 1: tenderness, erythema, swelling, and heat; Stage 2: blistering and bullae; Stage 3: crepitus, anesthesia, and skin necrosis.
36
What is Fournier gangrene and its typical clinical features?
Fournier gangrene is localized to the genitalia, perineum, anus, and occasionally the lower abdomen, typically presenting in patients aged 50 to 60 years.
37
What is the gold standard for diagnosing necrotizing fasciitis?
The gold standard for diagnosis is surgical consultation and exploration of the concerning site.
38
What are the key clinical features that suggest necrotizing fasciitis?
Key clinical features include erythema, edema, and pain involving the genitalia and surrounding skin, along with systemic symptoms.
39
What is the role of the LRINEC scoring system in necrotizing fasciitis?
The LRINEC scoring system helps detect early cases of necrotizing fasciitis, with a score of 6 points or more indicating high suspicion.
40
What are the mortality rates associated with necrotizing fasciitis?
Adult mortality rates range from 20% to 30%, while pediatric mortality rates are approximately 10% to 15%.
41
What surgical intervention is often considered for patients with extensive rectal involvement in necrotizing fasciitis?
For patients with extensive rectal involvement, diverting colostomy can be considered.
42
What is the most likely diagnosis for a patient with erythema, edema, and severe pain in the lower extremity?
The most likely diagnosis is necrotizing fasciitis, with the next step being immediate surgical consultation.
43
What is the diagnosis for a patient with erythema, edema, and pain in the genital area who is febrile and hypotensive?
The diagnosis is Fournier gangrene, and a CT scan can help delineate the extent of involvement.
44
What does a LRINEC score of 7 indicate?
A LRINEC score of 7 indicates a high likelihood of necrotizing fasciitis, with the next step being immediate surgical intervention.
45
What additional surgical procedure might be considered for a patient with necrotizing fasciitis involving the perineum?
A diverting colostomy might be considered to minimize fecal contamination.
46
What does a gray, dusky, edematous fascial plane on surgical exploration confirm?
This finding confirms the diagnosis of necrotizing fasciitis.
47
What does a LRINEC score of 4 indicate?
A LRINEC score of 4 indicates a low likelihood of necrotizing fasciitis.
48
What is the mainstay of therapy for necrotizing fasciitis?
The mainstay of therapy is rapid surgical intervention.
49
What is the recommended time frame for surgical intervention to improve clinical outcomes in necrotizing fasciitis?
Surgical intervention should occur less than 24 hours following onset.
50
What is a common surgical procedure for patients with limb disease due to necrotizing fasciitis?
Amputation may be necessary for patients with limb disease.
51
What is essential for achieving therapeutic success in necrotizing fasciitis treatment?
Full surgical debridement of all necrotic areas is essential.
52
What type of antibiotics are recommended for necrotizing fasciitis?
Broad-spectrum antibiotics are recommended.
53
What should be monitored closely in patients with necrotizing fasciitis?
Fluid resuscitation and electrolyte balance should be monitored closely.
54
What is the role of IV immunoglobulin in the treatment of necrotizing fasciitis?
Some benefit is suggested, but data is limited.
55
What is the recovery process like for patients who survive necrotizing fasciitis?
The recovery process is often long and laborious.
56
What is the significance of the anatomical location of disease in necrotizing fasciitis?
It has not been found to be a risk factor for mortality.
57
What is the importance of fluid resuscitation in the management of necrotizing fasciitis?
Fluid resuscitation is crucial due to significant drainage from lesions.
58
What are the defining features of gangrenous or necrotizing cellulitis?
Gangrenous or necrotizing cellulitis is characterized by rapidly progressive infection of the skin and subcutaneous tissue.
59
What is the management approach for necrotizing cellulitis?
The management includes surgical debridement and antimicrobial therapy.
60
What are the two major infections included in myonecrosis?
The two major infections are pyomyositis and clostridial gas gangrene.
61
What is the management approach for necrotizing cellulitis?
The management of necrotizing cellulitis includes:
1. **Surgical debridement** to remove necrotic tissue.
2. **Antimicrobial therapy** as outlined by the IDSA guidelines, which is essential for effective treatment.
62
What are the two major infections included in myonecrosis?
The two major infections included in myonecrosis are:
1. **Pyomyositis**
2. **Clostridial gas gangrene**
63
What factors increase the risk of developing pyomyositis?
Factors that increase the risk of developing pyomyositis include:
- Immunosuppression (e.g., HIV)
- Diabetes mellitus
- Preceding bacteremia or local skin and soft-tissue infections
- Localized trauma or muscle overuse
- Predilection sites are the lower extremities and pelvic girdle.
64
What is the prevalence of pyomyositis in the developed world?
The prevalence of pyomyositis in the developed world ranges from 1 per 1145 to 1 per 4000 hospital admissions, accounting for approximately 1% of all hospital admissions.
65
What does subcutaneous emphysema suggest about the type of infection?
Subcutaneous emphysema suggests a gas-forming infection, which could be clostridial or nonclostridial necrotizing cellulitis.
66
What is the most likely causative organism for necrotizing fasciitis after swimming in tropical waters?
The most likely causative organism is Vibrio vulnificus.
67
What is gangrenous or necrotizing cellulitis?
A type of necrotizing infection localized to the skin and subcutaneous tissue, not extending deep enough to involve the underlying fascia or muscles.
68
What is a defining feature of nonclostridial necrotizing cellulitis?
Subcutaneous emphysema.
69
What is the cornerstone of therapy for necrotizing infections?
Surgical debridement in conjunction with antimicrobial therapy.
70
What role does Panton-Valentine leukocidin play in pyomyositis?
It is thought to play a role in the development of pyomyositis and the ability to create intramuscular infections.
71
What are the defining features of Clostridial crepitant cellulitis?
**Clostridial crepitant cellulitis** is characterized by:
- Limited, superficial, and focal infections of the skin.
- Often presents without severe systemic symptoms.
- Extensive subcutaneous emphysema with minimal overlying skin changes.
- Tissue necrosis is limited to superficial skin and subcutaneous tissue.
72
What are the common predilection sites for pyomyositis infections?
Lower extremities and pelvic girdle, often following localized trauma or muscle overuse.
73
What is the gold standard for diagnosing pyomyositis?
MRI is the gold standard for diagnosing pyomyositis, as it can show muscle inflammation and intramuscular abscess formation.
74
What are the stages of clinical progression in pyomyositis?
| Stage | Description |
|-------|-------------|
| I | Inflammation and pain surrounding the infected muscle with associated leukocytosis; mild induration of subcutaneous tissue; cutaneous changes typically absent. |
| II | Suppuration with abscess formation within the muscle belly; severe focal pain, fever, and swelling over the affected muscle; lasts 1 to 3 weeks. |
| III | Progression to systemic disease with septic physiology, shock, and multifocal abscess formation. |
75
What factors increase the risk of mortality in pyomyositis?
- Septic physiology
- Hypotension
- Tachycardia
- Lower Glasgow coma score
- Higher Sequential Organ Failure Assessment (SOFA) score
- Elevated laboratory markers, including blood urea nitrogen, creatinine, bilirubin, and serum glutamic pyruvate transaminase.
76
What is the initial antimicrobial treatment for pyomyositis?
- Start broadly with **vancomycin**.
- For patients with multiple comorbidities, immunocompromised status, or developed infection, add **Piperacillin-tazobactam**, **ampicillin-tazobactam**, or **carbapenem** to vancomycin.
77
What distinguishes clostridial gas gangrene from clostridial crepitant cellulitis?
Clostridial gas gangrene is a much deeper infection characterized by severe necrosis of skeletal muscle, rapidly progressive, and often accompanied by severe systemic symptoms, with a risk for progression to multiorgan system shock.
78
What are the common pathogens associated with pyomyositis?
S. pneumoniae or Gram-negative enteric bacteria, and less commonly viral, parasitic, or fungal pathogens.
79
What are the clinical features of clostridial myonecrosis?
The clinical features include:
- **Acute abdominal pain** followed by localized pain in the limb.
- **Rapid progression** of lesions over 24 hours with color changes in the skin.
- **Severe pain** and **gas collection** in tissue manifesting as crepitus.
- **Brownish discharge** with a foul smell, described as 'dishwater exudate.'
- Symptoms resembling an **influenza-like prodrome** followed by tachycardia, fever, diaphoresis, and hypotension.
80
What is the triad of symptoms that is thought to be diagnostic of clostridial myonecrosis?
The triad of symptoms includes:
1. **Soft-tissue crepitus**
2. **Severe pain**
3. **Tachycardia disproportionate to fever**
81
What is the mainstay of therapy for patients with clostridial myonecrosis?
The mainstay of therapy includes:
- **Surgical debridement**
- **Multiple surgical debridements** and amputations as necessary
- **Intensive care unit-level care**
- **Broad-spectrum antibiotics** based on IDSA guidelines, typically clindamycin plus high-dose penicillin.
82
What are the mortality rates associated with clostridial myonecrosis?
Mortality rates for clostridial myonecrosis are reported to be as high as **100%**, particularly among patients who initially present in shock.
83
What is the significance of 'dishwater exudate' in clostridial myonecrosis?
The 'dishwater exudate' is a characteristic feature of clostridial myonecrosis, indicating severe tissue necrosis.
84
What does the presence of bullae filled with red-blue fluid indicate in necrotizing fasciitis?
The presence of bullae filled with red-blue fluid indicates advanced disease with significant tissue necrosis.
85
What systemic complications should be anticipated in a patient with necrotizing fasciitis who is febrile and hypotensive?
Systemic complications include septic shock, multiorgan failure, and disseminated intravascular coagulation.
86
What is 'water exudate'?
'Water exudate' is a characteristic feature of clostridial myonecrosis, indicating severe tissue necrosis.
87
What systemic complications should be anticipated in a febrile and hypotensive patient with necrotizing fasciitis?
Systemic complications include septic shock, multiorgan failure, and disseminated intravascular coagulopathy.
88
What are the most likely causative organisms in a patient with necrotizing fasciitis who has a history of IV drug use?
The most likely causative organisms are Clostridium sordellii and Clostridium novyi.
89
What are the most common causative organisms of clostridial myonecrosis?
Clostridium perfringens, Clostridium novyi, Clostridium histolyticum, Clostridium septicum, and Clostridium sordellii.
90
What is a prominent feature of clostridial myonecrosis?
Severe pain.
91
What is the triad of symptoms thought to be diagnostic of clostridial myonecrosis?
Soft-tissue crepitus, severe pain, and tachycardia disproportionate to fever.
92
What is the mainstay of therapy for clostridial myonecrosis?
Surgical debridement.
93
What is the mortality rate for clostridial myonecrosis among patients who initially present in shock?
As high as 100%.
94
What can progressive myonecrosis lead to?
Myoglobinuria and subsequent renal failure.
95
What is the recommended antibiotic therapy for clostridial myonecrosis?
Clindamycin plus high-dose penicillin.
96
What is a significant risk factor for developing spontaneous clostridial myonecrosis?
Underlying gastric malignancy or neutropenic gastritis.
97
What is the clinical significance of gas collection in clostridial myonecrosis?
It manifests as overlying crepitus and indicates severe infection.
98
What are the common causative organisms of spontaneous clostridial myonecrosis?
Clostridium perfringens, Clostridium novyi, Clostridium histolyticum, Clostridium septicum, and Clostridium sordellii.
99
What are the clinical features indicative of clostridial myonecrosis?
Key clinical features include:
- Acute abdominal pain followed by localized limb pain.
- Rapid progression of lesions within 24 hours, with color changes in the skin.
- Severe pain and crepitus in the affected area.
- Brownish discharge with a foul smell, described as 'dishwater exudate.'
- Symptoms resembling an influenza-like prodrome followed by tachycardia, fever, and hypotension.
- High risk for compartment syndrome and potential progression to shock and multiorgan failure.
100
What is the triad of symptoms that is thought to be diagnostic of clostridial myonecrosis?
The triad of symptoms indicative of clostridial myonecrosis includes:
1. Soft-tissue crepitus
2. Severe pain
3. Tachycardia disproportionate to fever.
101
What is the mainstay of therapy for patients with clostridial myonecrosis?
The mainstay of therapy for clostridial myonecrosis includes:
- Surgical debridement
- Multiple surgical interventions as needed
- Broad-spectrum antibiotics based on IDSA guidelines, typically clindamycin plus high-dose penicillin.
- Intensive care unit-level care is often required.
102
What are the mortality rates associated with clostridial myonecrosis, and what factors influence these rates?
Mortality rates for clostridial myonecrosis can be as high as 100%, particularly among patients who present in shock. Factors influencing these rates include:
- Delay in surgical intervention
- Severity of the initial presentation
- Presence of comorbid conditions.
103
What are the first-line antimicrobial agents for mixed infections in adults and their dosages?
The first-line antimicrobial agents for mixed infections in adults are:
- Piperacillin-tazobactam: 3.37 g q6h IV; 30 mg/kg/day in 2 divided doses
- Vancomycin: 30 mg/kg/day IV in 2 divided doses.
104
What is the pediatric dosage for meropenem in patients with necrotizing soft-tissue infections?
The pediatric dosage for meropenem is:
- Children 3 months to 12 years: 20 mg/kg/dose q8h IV.
105
What are the recommended agents for patients with severe penicillin allergy when treating Staphylococcus aureus infections?
For patients with severe penicillin allergy, the recommended agents for treating Staphylococcus aureus infections are:
- Vancomycin, Linezolid, Quinupristin/Dalfopristin, Daptomycin.
106
What is the adult dosage for clindamycin in treating necrotizing soft-tissue infections?
The adult dosage for clindamycin in treating necrotizing soft-tissue infections is:
- 600 to 900 mg q8h IV.
107
What is the pediatric dosage for doxycycline in treating Aeromonas hydrophila infections?
The pediatric dosage for doxycycline in treating Aeromonas hydrophila infections is:
- Not recommended for children; may need to use in life-threatening situations.
108
What is the first-line antimicrobial agent for mixed infections in adults according to the 2014 guidelines?
Piperacillin-tazobactam or vancomycin.
109
What is the recommended adult dosage for meropenem in treating necrotizing soft-tissue infections?
1 g q8h IV.
110
What is the pediatric dosage for piperacillin compared to the adult dosage?
60 to 75 mg/kg/dose q8h IV for pediatric patients, compared to 30 mg/kg/day in 2 divided doses for adults.
111
What is the first-line antimicrobial agent for treating Streptococcus infections?
Penicillin plus clindamycin.
112
What is the adult dosage for vancomycin for resistant strains?
30 mg/kg/day in 2 divided doses IV.
113
What is the pediatric dosage for clindamycin in treating necrotizing soft-tissue infections?
10 to 13 mg/kg/dose q8h IV.
114
What is the recommended treatment for Clostridium spp. infections?
Clindamycin plus penicillin.
115
What is the adult dosage for doxycycline in treating Aeromonas hydrophila infections?
100 mg q12h IV; 500 mg q12h IV; 1 to 2 g q24h IV.
116
What is the recommended treatment for Vibrio vulnificus infections?
Doxycycline plus ceftriaxone or cefotaxime.
117
What are the first-line antimicrobial agents recommended for treating mixed infections in patients with necrotizing soft-tissue infections, and what are their adult dosages?
The first-line antimicrobial agents for mixed infections are:
- Piperacillin-tazobactam: 3.375 g q6h IV; 30 mg/kg/day in 2 divided doses
- Vancomycin: 20 mg/kg/dose q8h IV.
118
What is the recommended dosage for meropenem in pediatric patients with necrotizing soft-tissue infections?
The recommended dosage for meropenem in pediatric patients is:
- Children 3 months to 12 years: 20 mg/kg/dose q8h IV.
119
What are the alternative agents for patients with severe penicillin allergy when treating Staphylococcus aureus infections?
For patients with severe penicillin allergy, the alternative agents for treating Staphylococcus aureus infections include:
- Vancomycin, linezolid, quinupristin/dalfopristin, daptomycin.
120
What is the pediatric dosage for clindamycin in treating infections caused by Clostridium spp. in children?
The pediatric dosage for clindamycin in treating infections caused by Clostridium spp. is:
- Children 1 to 13 years: 10 to 13 mg/kg/dose q8h IV.
121
What is the recommended adult dosage for doxycycline in treating infections caused by Aeromonas hydrophila?
The recommended adult dosage for doxycycline in treating infections caused by Aeromonas hydrophila is:
- 100 mg q12h IV; 500 mg q12h IV.
