151: Cellulitis and Erysipelas Flashcards
What are the common clinical features of cellulitis?
- Ill-defined erythema and edema
- Often warm and painful
- Most common site: lower extremity (adults); also upper extremities, trunk, head, and neck
- Facial involvement: children > adults
- Majority unilateral; bilateral involvement prompts consideration of an alternative diagnosis
- Linear streaking, lymphangiitis, and tender regional lymphadenopathy may be observed
- Peau d’orange appearance indicates significant involvement of lymphatics or superficial edema
- Bulla formation and superficial necrosis may occur
- Hemorrhage can occur due to disruption of superficial vessels by inflammation and edema
- Crepitus, anesthesia, or disproportionate pain should raise concern for necrotizing soft-tissue infection.
What are the complications associated with cellulitis?
- Lymphedema from lymphatic damage, increasing the risk of recurrence
- Superficial thrombophlebitis, which may be seen in the acute setting
- Bacteremia (5%) leading to sepsis, bacterial endocarditis, postinfectious glomerulonephritis, and toxin-mediated systemic syndromes
- Spread of infection to deeper tissues is rare in the absence of other risk factors or chronic systemic disease.
How does erysipelas differ from classic cellulitis?
Feature | Erysipelas | Classic Cellulitis |
|———|————|——————-|
| Area of Involvement | Sharply demarcated and bright red | Ill-defined plaques |
| Most Common Site | Leg (76%-90%) | Lower extremity |
| Fever | More common | Less common |
| Recurrence | May be observed | Less common |
| Systemic Complications | Uncommon | More common |
What are the noncutaneous findings associated with cellulitis?
- Fever: inconsistent complication, seen in 12% to 71% of hospitalized patients
- Tachycardia
- Hemodynamic instability, requiring prompt assessment for complicating sepsis or other serious infections.
What is the epidemiology of cellulitis in the United States?
- Common condition with increased prevalence from 4.6 million in 1997 to 9.6 million in 2005
- Incidence rate increased from 17.3 to 32.5 per 1000 population during this time, paralleling the rise of community-acquired MRSA
- > 10% of hospitalizations for infectious diseases in the United States
- Recurrent cellulitis occurs in 22% to 49% of patients, most of whom can be managed in the ambulatory setting.
A 45-year-old patient presents with unilateral lower extremity erythema, warmth, and swelling. What is the most likely diagnosis, and what are the cardinal signs to confirm it?
The most likely diagnosis is cellulitis. Cardinal signs include erythema, swelling, warmth, and pain.
A patient presents with erysipelas involving the face. What are the distinguishing features of erysipelas compared to cellulitis?
Erysipelas is characterized by sharply demarcated, bright red areas of involvement, often with fever, compared to the ill-defined plaques of cellulitis.
A patient with cellulitis has a history of obesity and presents with erythema and edema. What is the most common site of cellulitis in adults?
The most common site of cellulitis in adults is the lower extremity.
A patient with cellulitis has a history of systemic illness and presents with erythema and pain. What are the cardinal signs of cellulitis?
The cardinal signs of cellulitis are erythema, swelling, warmth, and pain.
A patient with cellulitis has a history of systemic illness and presents with erythema and scaling. What is the most common site of erysipelas?
The most common site of erysipelas is the leg.
What is the most common site for cellulitis in adults?
Lower extremity.
What are the classic signs of inflammation associated with cellulitis?
Redness, swelling, heat, and pain.
What is a common complication of cellulitis related to lymphatic damage?
Lymphedema.
What percentage of hospitalized patients experience fever as a complication of cellulitis?
12% to 71%.
What is the typical appearance of erysipelas compared to classic cellulitis?
Erysipelas has a sharply demarcated and bright red area of involvement.
What is a significant risk factor for recurrent cellulitis?
Lymphedema from lymphatic damage.
What should raise concern for a necrotizing soft-tissue infection in cellulitis cases?
Crepitus, anesthesia, or pain disproportionate to clinical findings.
What is the incidence rate of cellulitis in the United States from 1997 to 2005?
Increased from 4.6 million in 1997 to 9.6 million in 2005.
What is the most common clinical variant of cellulitis?
Erysipelas.
What type of cellulitis is characterized by the presence of pustules or abscesses?
Purulent cellulitis.
What are the common clinical features of cellulitis and how do they differ from erysipelas?
Cellulitis:
- Ill-defined erythema and edema
- Often warm and painful
- Most common site: lower extremity
- Unilateral involvement is typical
Erysipelas:
- Sharply demarcated and bright red area
- Most common site: leg (76%-90%)
- Fever is more common than in cellulitis
- Recurrence may be observed
Both conditions share classic signs of inflammation: redness, swelling, heat, and pain.
What complications can arise from cellulitis and how do they impact patient management?
Complications of cellulitis include:
1. Lymphedema:
- From lymphatic damage
- Increases risk of recurrence
-
Superficial thrombophlebitis:
- May be seen in acute settings
- Decreases risk of deep venous thrombosis
-
Bacteremia (5%):
- Can lead to sepsis, bacterial endocarditis, and other serious complications
-
Spread of infection to deeper tissues:
- Rare in absence of other risk factors or chronic disease
These complications necessitate prompt assessment for sepsis and may require more aggressive treatment strategies.
How does the clinical presentation of cellulitis differ in children compared to adults?
In children, cellulitis often presents with:
- Facial involvement being more common than in adults.
- Bilateral involvement may prompt consideration of alternative diagnoses, which is less common in adults.
- Lower extremities are still the most common site, but the overall presentation may be more severe due to the child’s immune response.
In adults, the most common site remains the lower extremities, with unilateral involvement being typical.
What are the key considerations for diagnosing cellulitis in the presence of systemic symptoms?
When diagnosing cellulitis with systemic symptoms, consider the following:
- Fever: Inconsistent complication; occurs in 12% to 71% of hospitalized patients.
- Tachycardia and hemodynamic instability may indicate complicating factors such as sepsis or toxin-mediated systemic illness.
- Pain disproportionate to clinical findings (e.g., crepitus or anesthesia) should raise concern for necrotizing soft-tissue infections.
Prompt assessment and management are crucial to prevent severe complications.
What are the implications of recurrent cellulitis in patients and how should it be managed?
Recurrent cellulitis occurs in 22% to 49% of patients and can lead to:
- Increased morbidity and healthcare costs.
- Frequent complications such as lymphedema, which increases the risk of future episodes.
Management strategies include:
1. Identifying and addressing risk factors (e.g., skin barrier issues, obesity).
2. Prophylactic antibiotics may be considered in patients with frequent recurrences.
3. Patient education on skin care and early recognition of symptoms to seek prompt treatment.
What are the common clinical features of bilateral cellulitis?
Bilateral cellulitis is characterized by infection occurring simultaneously on both extremities, which is rare without predisposing factors such as penetrating trauma. It is often misdiagnosed and is associated with deficient cellular immunity, such as in solid organ transplantation recipients or individuals with HIV, leading to a significantly increased risk of true bilateral infection.
What are the primary microbial pathogens associated with cellulitis?
The most common microbial pathogens associated with cellulitis include:
Pathogen | Type |
|———-|——|
| Group A β-hemolytic streptococci (Streptococcus pyogenes) | Bacterial |
| Staphylococci (particularly Staphylococcus aureus) | Bacterial |
| Haemophilus influenzae Type B | Bacterial |
| Enterococci | Bacterial |
| Pseudomonas spp. | Bacterial |
| Gram-negative anaerobes | Bacterial |
| Mycobacteria | Bacterial |
| Cryptococcus | Fungal |
What are the risk factors for developing cellulitis?
The risk factors for developing cellulitis include:
Risk Factor | Description |
|————-|————-|
| Age | Increased risk with advancing age |
| Obesity | Markedly increases risk |
| Renal or hepatic disease | Compromises immune function |
| Connective tissue disease | Increases susceptibility |
| Malignancy | Associated with immunocompromised states |
| Immunodeficiency | Including iatrogenic or systemic conditions (e.g., HIV, diabetes) |
| Disruption of skin barrier | From lymphedema, trauma, or surgical interventions |
What is the significance of lymphedema in relation to cellulitis risk?
Lymphedema significantly increases the risk of cellulitis, conferring a risk that is more than 70-fold higher compared to individuals without lymphedema. This is followed by disruption of the skin barrier, which increases the risk by nearly 24-fold. These factors are critical in understanding the predisposition to recurrent cellulitis.
What are the common diagnostic challenges associated with cellulitis?
The diagnosis of cellulitis is often challenging due to:
- High misdiagnosis rates (>30%) due to clinical mimics known as pseudocellulitis.
- Reliance on clinical history and physical examination, as there are no reliably accurate diagnostic studies.
- Cardinal symptoms such as erythema, swelling, warmth, and pain can overlap with other conditions, complicating the diagnosis.
A patient presents with bilateral lower extremity erythema. What alternative diagnoses should be considered, and why is bilateral cellulitis rare?
Alternative diagnoses include stasis dermatitis, deep venous thrombosis, and chronic lymphedema. Bilateral cellulitis is rare without predisposing factors like trauma or immunodeficiency.
A patient with cellulitis has a history of aquatic trauma. What atypical organisms should be considered, and what diagnostic steps should be taken?
Atypical organisms include Aeromonas spp., Vibrio vulnificus, and Mycobacterium marinum. Biopsy for histopathologic evaluation and tissue culture should be performed.
A patient with cellulitis has a history of toe web infections. What is the significance of this history, and how should it be managed?
Toe web infections are a common portal of entry for cellulitis. Management includes treating the underlying infection to prevent recurrence.
A patient with cellulitis has a history of obesity and prior surgical site intervention. What are the most important risk factors for recurrent cellulitis?
The most important risk factors include lymphedema, age, obesity, and prior surgical site intervention.
A patient with cellulitis has a history of MRSA colonization. What diagnostic test can confirm MRSA carriage, and what is its clinical significance?
PCR swabs can confirm MRSA carriage, which correlates with an increased overall risk of cellulitis.
A patient with cellulitis has a history of recurrent episodes and presents with fever and leukocytosis. What serologic tests can assist in diagnosis?
Serologic tests like antistreptolysin O and anti-DNase B can assist but are limited in distinguishing acute infection from prior exposure.
A patient with cellulitis has a history of aquatic trauma and presents with erythema and edema. What atypical organisms should be considered?
Atypical organisms include Aeromonas spp., Vibrio vulnificus, and Mycobacterium marinum.
A patient with cellulitis has a history of systemic illness and presents with erythema and edema. What is the most common organism involved?
The most common organisms involved are Group A β-hemolytic streptococci and Staphylococcus aureus.
A patient with cellulitis has a history of systemic illness and presents with erythema and pain. What is the most common cause of cellulitis?
The most common cause of cellulitis is bacterial infection, primarily by Group A β-hemolytic streptococci and Staphylococcus aureus.
What are the common causes of bilateral cellulitis?
Infection occurs simultaneously on both extremities, often misdiagnosed, and can be associated with penetrating trauma or deficient cellular immunity.
What is the most common etiology for cellulitis?
Toe web infections are identified as the most common etiology for cellulitis.
What are the typical microbial pathogens associated with cellulitis?
Group A β-hemolytic streptococci (Streptococcus pyogenes) and staphylococci (particularly S. aureus) are the most common pathogens.
What are the risk factors for developing cellulitis?
Risk factors include male gender, summer months, increasing patient age, obesity, renal or hepatic disease, connective tissue disease, malignancy, and immunodeficiency.
What is the significance of lymphedema in relation to cellulitis?
Lymphedema confers the highest risk for cellulitis, with a risk increase of more than 70-fold.
What are the cardinal symptoms of cellulitis?
Cardinal symptoms include erythema, swelling, warmth, and pain, often accompanied by fever and leukocytosis.
What is the role of laboratory testing in diagnosing cellulitis?
Laboratory testing can show leukocytosis and elevated inflammatory markers, but these findings are nonspecific and may also be present in pseudocellulitis.
How can misdiagnosis rates affect the treatment of cellulitis?
Misdiagnosis rates for cellulitis can exceed 30%, leading to unnecessary antibiotic use and prolonged treatment.
