Definition
A.Soft tissue infection primarily involving the skin that spreads and is frequently characterized by redness, warmth, swelling, and pain.
B.Cellulitis commonly occurs when there is a break in the skin.
C.An abscess may or may not be involved.
Incidence
A.May occur at any age.
B.More common in males.
C.May occur after an abrasion or surgical incision.
D.Typically in extremities, especially lower extremities.
E.Highly seasonal, more likely to occur during warmer summer months.
F.Costs $3.74 billion annually; 30% of patients diagnosed with cellulitis are misdiagnosed, leading to unnecessary hospitalization and antibiotic use.
Pathogenesis
A.Most commonly caused by Group A beta-hemolytic streptococcus or methicillin-susceptible Staphylococcus aureus (MSSA).
B.Other less common causes.
1.Other beta-hemolytic streptococcus.
2.Methicillin-resistant Staphylococcus aureus (MRSA).
3.Streptococcus pyogenes (presents with lymphangitis).
4.Pseudomonas aeruginosa.
5.Erysipelothrix rhusiopathiae from contact with raw meat (poultry, fish, other meat) typically seen in butchers or other handlers.
6.Vibrio species from saltwater swimming, sea urchin impalement, or contact with raw seafood.
7.Aeromonas hydrophilia from fresh water swimming.
8.Pasteurella multocida from animal bite or injury.
Predisposing Factors
A.Injury or cut in affected area (abrasion, surgical incision, intravenous (IV) drug abuse, insect/animal bites, etc.).
B.Previous cellulitis.
C.Decreased mobility.
D.Impairment of vascular–lymphatic system.
1.Venous insufficiency.
2.Lymphedema due to impaired lymphatic drainage.
3.Lymph node resection.
4.Prior radiation treatments to affected area.
E.Chronic comorbidity conditions.
1.Malnourishment, obesity, diabetes, chronic kidney disease, chronic liver disease, alcohol abuse.
2.Immunosuppression (HIV, cancer, taking immunosuppressive agents).
3.Tinea pedis or other dermatitis-affected skin integrity.
Subjective Data
A.Common complaints/symptoms.
1.Elicit onset and duration of symptoms.
2.Edema.
3.Erythema.
4.Tenderness or pain.
B.Common/typical scenario.
1.Expanding sore erythematous edematous patch on lower extremity for 1 to 2 days, possibly near recent wound or injury.
C.Family and social history.
1.Alcohol abuse.
2.IV drug abuse.
3.Any trauma to affected areas.
D.Review of systems.
1.May have malaise.
2.Fevers.
3.Chills.
4.Regional lymphadenopathy.
5.Decreased mobility due to pain or swelling.
Physical Examination
A.One extremity (if bilateral it is very unlikely to be cellulitis. Stasis dermatitis is often bilateral and frequently misdiagnosed as cellulitis).
B.Usually a somewhat well-demarcated erythematous patch (a sharply demarcated indurated border increases likelihood of erysipelas; see Figure 15.2).
C.Tender.
D.Mild to moderate swelling.
E.Sometimes regional lymphadenitis (tender or enlarged) or lymphangitis.
F.Rarely blisters, necrosis.
G.If palpate warmth, need to rule out deep vein thrombosis (DVT).
H.If exquisite tenderness and rapid progression occurs, rule out necrotizing fasciitis.
I.Systemic signs of toxicity: Fever, hypotension, tachycardia.
Diagnostic Tests
A.Culture—when purulent discharge is present. Majority cannot be cultured unless abscess present for incision and drainage.
B.Biopsy—poor healing and low diagnostic yield.
C.Lab—elevated sedimentation rate and leukocytosis.
Differential Diagnosis
A.Stasis dermatitis.
B.Lipodermatosclerosis.
C.DVT.
D.Folliculitis.
E.Insect bite reaction.
F.Contact dermatitis.
G.Erysipelas.
H.Necrotizing fasciitis.
Evaluation and Management Plan
A.General plan.
1.Antibiotics coverage for either gram-positive (most common), MRSA, or gram-negative (rare).
2.Keep affected extremity raised.
FIGURE 15.2 (A) An example of cellulitis. (B) Cellulitis resulting from a vaccination for varicella.
Source: Lyons, F., & Ousley, L. (2015). Dermatology for the advanced practice nurse. New York, NY: Springer Publishing Company.
3.Draw line on borders to monitor improvement or worsening.
4.If drainable abscess, incise and drain affected lesion.
5.If systemic symptoms present, check blood cultures first then initiate IV antibiotics.
6.Point of care ultrasound to differentiate abscess from cellulitis (which usually has cobblestone appearance).
B.Patient/family teaching points.
1.Keep affected extremity elevated.
2.Bathe once daily and clean area once daily with gentle soap and water.
3.Do not squeeze or irritate area.
4.If pain or rash is worsening, notify provider.
C.Pharmacotherapy.
1.Antibiotics for staphylococcus and streptococcus coverage: Dicloxacillin, azithromycin, clarithromycin, celphalexin, or cefazolin for 5 days.
2.Antibiotics for MRSA coverage: Clindamycin, trimethoprim-sulfamethoxazole, doxycycline, minocycline, linezolid, or tedizolid for 5 to 10 days.
3.Antibiotics for those with systemic signs of toxicity or who have extensive skin involvement, close proximity to indwelling medical device, inability to tolerate oral therapy, prior episode of MRSA or known colonization, or lack of response to antibiotic regimen that does not cover for MRSA.
a.Empiric IV therapy for MRSA: Vancomycin or daptomycin.
b.Once signs of infection are resolving, switch to oral regimen with coverage for MRSA and streptococcus.
4.Antibiotics for those with systemic signs of toxicity or who have extensive skin involvement with at least one of the following: Perioral/perirectal abscess, possible connection to pressure ulcer, or skin necrosis.
a.Empiric IV therapy for MRSA.
b.Start vancomycin or daptomycin with another antibiotic(s) to cover for gram-positive, gram-negative, and anaerobes.
D.Discharge instructions.
1.Complete course of antibiotics as directed by the provider.
2.Review with patient the common side effects of given antibiotic treatment (nausea, diarrhea, rash, and thrush/yeast infections).