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?
Erysipelas
- Sharply demarcated and bright red
- Leg (76%-90%)
- Fever more common
- Recurrence may be observed
- Systemic complications less common
Classic Cellulitis
- Ill-defined plaques
- Lower extremity
- Fever less common
- Recurrence less common
- Systemic complications 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.
Delete
- 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.
Delete
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.
Delete
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.
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:
- Group A β-hemolytic streptococci (Streptococcus pyogenes)
- Staphylococci (particularly Staphylococcus aureus)
- Haemophilus influenzae Type B
- Enterococci
- Pseudomonas spp.
- Gram-negative anaerobes
- Mycobacteria
- Cryptococcus
What are the risk factors for developing cellulitis?
- 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 infection. What are the most important risk factors for recurrent cellulitis?
The most important risk factors include lymphedema, age, obesity, and prior surgical site infection.
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.
Delete
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.
What is the importance of consulting a dermatologist in cellulitis cases?
Consultation with a dermatologist can improve diagnostic accuracy and shorten unnecessary antibiotic use, enhancing clinical outcomes.
What are the limitations of microbial cultures in diagnosing cellulitis?
Skin swabs and surface wound cultures are often unhelpful due to polymicrobial infections, and PCR swabs for MRSA may not be useful in acute infections.
What are the key clinical features that differentiate bilateral cellulitis from other types of 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.
Delete
The most common pathogens associated with cellulitis are Group A β-hemolytic streptococci (Streptococcus pyogenes) and staphylococci (particularly S. aureus). In hospitalized patients, other streptococcal species and coagulase-negative staphylococci may be increasingly important.
Delete
Deficient cellular immunity is associated with conditions such as solid organ transplantation recipients or individuals with HIV, leading to a significantly increased risk of true bilateral infection.
What are the most common microbial pathogens associated with cellulitis?
The most common pathogens associated with cellulitis are Group A β-hemolytic streptococci (Streptococcus pyogenes) and staphylococci (particularly S. aureus). In hospitalized patients, other streptococcal species and coagulase-negative staphylococci may be increasingly important. In children, Haemophilus influenzae Type B can be present in up to 6% of cases. Polymicrobial infections may also occur, especially in immunocompromised patients.
What are the primary risk factors for developing recurrent cellulitis?
The primary risk factors for recurrent cellulitis include lymphedema, age, obesity, and prior surgical site intervention.
Delete
The diagnosis of cellulitis is primarily made through clinical history and physical examination, as there are no reliably accurate diagnostic studies. Misdiagnosis rates exceed 30%, and consulting a dermatologist can improve diagnostic accuracy.
What laboratory tests are commonly used in the evaluation of cellulitis?
Common laboratory tests include leukocytosis (≥ 10,000 cells/μL), inflammatory markers (ESR and CRP), procalcitonin, and serologic tests. These tests have limitations, including nonspecificity and variability in results.
What is the diagnostic usefulness of needle aspiration followed by aspirate culture in cellulitis cases?
Needle aspiration followed by aspirate culture has a diagnostic usefulness of 5% to 40%, but may be more useful in patients with underlying systemic risk factors.
What are the key imaging techniques used in diagnosing cellulitis?
Key imaging techniques include ultrasonography or MRI for identifying localized fluid collections, and CT or MRI for differentiating cellulitis from necrotizing soft-tissue infections.
What is the ALT-70 risk prediction model used for?
The ALT-70 risk prediction model is used to predict the likelihood of lower-extremity cellulitis among admitted patients based on asymmetry of infection, leukocytosis, tachycardia, and patient age.
What are the common differential diagnoses for pseudocellulitis?
The most common cause of pseudocellulitis is stasis dermatitis, characterized by bilateral presentation, chronicity, scaling and pruritus, and absence of fever or leukocytosis.
What is the prognosis for patients with uncomplicated cellulitis treated with antibiotics?
The prognosis is generally good, with modern mortality rates being negligible and cure rates averaging approximately 80% to 85%.
How can treatment response be monitored in a patient with cellulitis?
Outlining the involved area of cellulitis and using serial high-quality photographs can help monitor treatment response.
How would you use the ALT-70 risk prediction model in a 70-year-old patient with tachycardia and leukocytosis?
A score ≥5 indicates a high likelihood of lower-extremity cellulitis.
What is the most likely diagnosis for a patient with cellulitis presenting with scaling and pruritus but no fever?
The most likely diagnosis is stasis dermatitis, confirmed by response to compression, elevation, and topical corticosteroids.
What is the immediate management step for a patient with cellulitis and a necrotizing soft-tissue infection?
Immediate surgical evaluation and debridement are required.
What imaging modality can assist in diagnosing purulent fluid collections in a patient with cellulitis?
Ultrasonography or MRI can help identify localized fluid collections for guidance of incision and drainage.
What laboratory tests should be performed for a patient with cellulitis and a history of immunodeficiency?
Tests include leukocyte count, ESR, CRP, and blood cultures, especially in high-risk populations.
What is the differential diagnosis for a patient with a history of erythema migrans in an endemic area?
The differential diagnosis includes Lyme disease, characterized by the classic annular configuration of erythema migrans.
What is the first step in management for a patient with cellulitis and a history of diabetes presenting with purulent fluid collections?
The first step is incision and drainage of purulent fluid collections, followed by culture and sensitivity testing.
What is the most common cause of pseudocellulitis?
The most common cause is stasis dermatitis.
What is the cure rate for cellulitis?
The cure rate is approximately 80% to 85%.
What is the recurrence rate for cellulitis?
The recurrence rate is greater than 10%.
What is the role of blood cultures in uncomplicated cellulitis?
Blood cultures are not routinely performed; positive in only approximately 5% of cases.
What are the recommended empiric antibiotic therapies for nonpurulent cellulitis without systemic evidence of infection?
Oral antistreptococcal antibiotics include cephalexin, dicloxacillin, penicillin V, and clindamycin or macrolides for Type I hypersensitivity reactions.
What are the indications for parenteral antibiotics in patients with evidence of systemic infection due to cellulitis?
Indications include meeting systemic inflammatory response syndrome criteria, with recommended parenteral antibiotics such as cefazolin and vancomycin.
What is the recommended duration of antibiotic therapy for uncomplicated cellulitis?
The recommended duration is 5 days, with reassessment at 24 to 72 hours.
What are the prophylactic antibiotic options for patients with recurrent cellulitis?
Prophylactic antibiotics may include low-dose penicillin or erythromycin for patients with 3 to 4 recurrences per year.
What adjunctive treatments are recommended for cellulitis according to the guidelines?
Combination therapy with antibiotics and adjunctive antiinflammatories such as NSAIDs and systemic corticosteroids may be considered.
What preventive measures should be taken for a patient at risk of cellulitis?
Preventive measures include addressing predisposing factors like lymphedema and skin barrier defects.
What empiric antibiotic therapy should be initiated for a patient with purulent cellulitis and a history of MRSA colonization?
Empiric therapy should include antibiotics effective against MRSA, such as clindamycin, tetracyclines, or trimethoprim-sulfamethoxazole.
What is the recommended treatment approach for a patient with cellulitis meeting systemic inflammatory response syndrome criteria and with suspected MRSA?
Parenteral antibiotics such as cefazolin or vancomycin should be initiated.
What alternative antibiotics can be used for mild nonpurulent cellulitis in patients with penicillin allergy?
Clindamycin or macrolides can be used as alternatives.
What prophylactic measures can be considered for a patient with recurrent cellulitis, and what are their limitations?
Prophylactic antibiotics may reduce recurrence but have diminishing effects after discontinuation.
What adjunctive treatment should be avoided in a patient with cellulitis and a history of varicella?
NSAIDs should be avoided as they increase the risk of skin infection.
What are the IDSA guidelines regarding corticosteroid use in cellulitis?
Systemic corticosteroids may be considered in nondiabetic adult patients to reduce resolution time.
What is the recommended treatment approach for a patient with cellulitis and a history of systemic illness presenting with tachycardia and hypotension?
Broad-spectrum parenteral antibiotics should be initiated.
DELETE
The most effective strategy is treating predisposing factors like lymphedema.
What adjunctive treatment can reduce healing time in a patient with uncomplicated erysipelas?
Systemic corticosteroids like prednisolone can reduce healing time in uncomplicated erysipelas.
What is the most effective preventive strategy for a patient with cellulitis and lymphedema?
The most effective strategy is treating predisposing factors like lymphedema and addressing local skin barrier defects.
DELETE
Systemic corticosteroids like prednisolone can reduce healing time in uncomplicated erysipelas.
What is the duration of treatment for uncomplicated cellulitis?
The duration of treatment for uncomplicated cellulitis is 5 days, according to IDSA guidelines. Extend if the infection persists.
DELETE
5 days, extend if signs of infection persist.
What are the first-line oral antibiotics for nonpurulent cellulitis without systemic evidence of infection?
Cephalexin, dicloxacillin, penicillin V. If with Type 1 hypersensitivity to the above, alternatives are clindamycin or macrolides.
What should be done for patients with evidence of systemic infection without hypotension or end-organ damage due to nonpurulent cellulitis?
They should receive parenteral antibiotics such as cefazolin, ceftriaxone, penicillin G.
Alternatives: clindamycin, vancomycin (if with IVDU or known MRSA)
DELETE
Combination therapy with antibiotics and adjunctive antiinflammatories, including NSAIDs and systemic corticosteroids, can be beneficial.
DELETE
Underlying medical conditions, lymphedema, and local skin barrier defects.
DELETE
Prophylactic antibiotics may be considered if there are 3 to 4 recurrences per year, though this is controversial.
What is the significance of reassessment at 24 to 72 hours in cellulitis treatment?
It is important to assess the response to therapy.
What are the first-line agents of choice for MRSA in mild purulent cellulitis?
Clindamycin, tetracyclines, and trimethoprim-sulfamethoxazole.
What is the recommended treatment for MRSA in moderate purulent cellulitis?
Vancomycin, clindamycin, or linezolid.
What are the systemic inflammatory response syndrome criteria for cellulitis?
Temperature >38°C, pulse >90 beats/min, respiratory rate >20 breaths/min, leukocyte count >12,000 cells/μL or <4000 cells/μL.
What are the recommended empiric antibiotic therapies for nonpurulent cellulitis without systemic evidence of infection?
The recommended empiric antibiotic therapies include:
- Oral antistreptococcal antibiotics:
- Cephalexin
- Dicloxacillin
- Penicillin V
- Clindamycin or macrolides (for Type I hypersensitivity reactions to penicillins or cephalosporins)
- Note: There is no significant difference in failure rates between β-lactams and non-β-lactams, but treatment-related adverse events are higher with non-β-lactams.
What are the indications for parenteral antibiotics in patients with systemic infection due to moderate nonpurulent cellulitis?
Indications include:
- Presence of 2 or more systemic inflammatory response syndrome criteria:
- Temperature >38°C [100.4°F] or <36°C [96.8°F]
- Pulse >90 beats/min
- Respiratory rate >20 breaths/min
- Leukocyte count >12,000 cells/μL or <4000 cells/μL
- Failure of outpatient treatment.
- Recommended parenteral antibiotics:
- Cefazolin
- Ceftriaxone
- Penicillin G
- Clindamycin (for Type I hypersensitivity reactions to penicillins or cephalosporins)
- Vancomycin (for associated penetrating trauma or known MRSA colonization)
What is the recommended duration of treatment for uncomplicated cellulitis and cellulitis involving the immunocompromised according to IDSA guidelines?
According to IDSA guidelines, the recommended duration is:
- Uncomplicated cases: 5 days
- If signs of infection persist: extend treatment
- General recommendations:
- Uncomplicated: 5-10 days
- Immunocompromised: 7-14 days
- Reassessment at 24 to 72 hours is important.
What adjunctive treatments are recommended for cellulitis and what are their effects?
Adjunctive treatments include:
- Combination therapy with antibiotics and adjunctive anti-inflammatories:
- NSAIDs: Decrease time to regression of inflammation; increased risk of skin infection in children with varicella.
- Prednisolone: Decrease time to healing in uncomplicated erysipelas with a trend toward decreased relapse.
- Oral corticosteroids: Decrease resolution time and ocular complications in orbital cellulitis.
- IDSA guidelines recommend consideration of systemic corticosteroids in nondiabetic adult patients.
What are the prevention strategies for recurrent cellulitis?
Prevention strategies include:
- Treatment of predisposing factors:
- Lymphedema
- Toe web infections
- Local skin barrier defects
- Underlying medical conditions
- Decolonization strategies for MRSA carriage: Controversial but may be considered.
What is the most common site of cellulitis?
The most common site of cellulitis is the lower extremities.
DELETE
Significant involvement of the lymphatics or superficial edema would appear with lymphangitis.
What is the most common site of erysipelas?
The most common site of erysipelas is the leg (76-90%) > face > upper extremity.
What are the most common organisms involved in cellulitis?
The most common organisms involved are Streptococcus pyogenes and Staphylococcus aureus.
DELETE
The most important risk factors include:
1. Lymphedema
2. Venous insufficiency
3. Previous episodes of cellulitis
4. Skin breaks or ulcers.
When do ASO and Anti-DNase B peak?
ASO appears after 1 week and peaks at 3-6 weeks; Anti-DNase B peaks at 6-8 weeks.
What are the cure rates for cellulitis treatment?
Cure rates are 80-90% and are more common in uncomplicated cases.
What is important to assess response to therapy in cellulitis treatment?
Reassessment at 48-72 hours is important to assess response to therapy.
What is the most common cause of pseudocellulitis?
The most common cause of pseudocellulitis is insect bites.
What percentage of patients experience recurrence of cellulitis?
Recurrence occurs in 30-50%.
What should be done if signs of infection persist after initial treatment?
Extend treatment duration and reassess.
What is the recommended reassessment time to assess response to therapy?
At 48-72 hours.
