What is the diagnosis and treatment for cellulitis?

From the Guidelines

Cellulitis should be treated with antibiotics that are active against streptococci, and the recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period 1.

Diagnosis and Treatment

Cellulitis is a common bacterial skin infection that affects the deeper layers of skin and the subcutaneous tissue. It typically presents as a red, swollen, painful, and warm area of skin, often with poorly defined borders.

• The diagnosis of cellulitis is primarily clinical, based on the presentation and physical examination of the patient.
• Laboratory tests, such as blood cultures, may be ordered in severe cases or in patients who are not responding to treatment.

Antibiotic Treatment

• For mild cases of cellulitis, oral antibiotics like cephalexin (500 mg four times daily), dicloxacillin (500 mg four times daily), or amoxicillin-clavulanate (875/125 mg twice daily) for 5-10 days are typically effective 1.
• For more severe cases requiring hospitalization, intravenous antibiotics such as cefazolin, nafcillin, or vancomycin may be necessary 1.

Additional Measures

• Elevation of the affected area, rest, and application of warm compresses can help improve circulation and reduce swelling 1.
• It's crucial to complete the full course of antibiotics even if symptoms improve.

Prevention of Recurrence

• Measures to reduce recurrences of cellulitis include treating interdigital maceration, keeping the skin well hydrated with emollients, and reducing any underlying edema 1.
• Prophylactic antibiotics may be considered in patients with frequent recurrences of cellulitis 1.

From the FDA Drug Label

14 CLINICAL STUDIES 14. 1 Acute Bacterial Skin and Skin Structure Infections

Adults A total of 1333 adults with acute bacterial skin and skin structure infections (ABSSSI) were randomized in two multicenter, multinational, double-blind, non-inferiority trials. Patients with cellulitis/erysipelas, major cutaneous abscess, or wound infection were enrolled in the trials The types of ABSSSI included were cellulitis/erysipelas (41%), wound infection (29%), and major cutaneous abscess (30%) The primary endpoint in Trial 1 was early clinical response defined as no increase from baseline lesion area at 48-72 hours after the first dose and oral temperature of ≤37. 6°C, confirmed by a second temperature measurement within 24 hours in the ITT population.

The diagnosis of cellulitis is based on clinical presentation, including local signs and symptoms of infection, as well as regional or systemic signs of infection, such as:

• Lymphadenopathy
• Temperature 38°C or higher
• White blood cell count greater than 10,000 cells/mm3 or less than 4000 cells/mm3
• 10% or more band forms on white blood cell differential The treatment for cellulitis includes antibiotics, such as tedizolid (SIVEXTRO) 200 mg once daily for 6 days, as compared to linezolid 600 mg every 12 hours for 10 days 2.

From the Research

Diagnosis of Cellulitis

• Cellulitis is a clinical diagnosis based on the history of present illness and physical examination, and lacks a gold standard for diagnosis 3.
• Clinical presentation with acute onset of redness, warmth, swelling, and tenderness and pain is typical 3.
• Microbiological diagnosis is often unobtainable due to poor sensitivity of culture specimens 3.

Treatment of Cellulitis

• The majority of non-purulent, uncomplicated cases of cellulitis are caused by β-hemolytic streptococci or methicillin-sensitive Staphylococcus aureus, and appropriate targeted coverage of this pathogen with oral antibiotics such as penicillin, amoxicillin, and cephalexin is sufficient 3.
• Even with rising rates of community-acquired methicillin-resistant Staphylococcus aureus, coverage for non-purulent cellulitis is generally not recommended 3.
• The use of long-term oral antibiotics has been advocated to prevent recurrent cellulitis episodes, but when recurrences occur despite long-term antibiotic use, limited options are available 4.
• A "pill in the pocket" approach with the use of oral tedizolid has been discussed as a unique treatment approach for preventing severe cellulitis 4.
• The recommended duration of antibiotic therapy for patients hospitalized with cellulitis is 5-14 days, and factors that affect the duration of treatment include patient age, C-reactive protein levels, coexisting diabetes mellitus, and coexisting blood stream infection 5.
• Antibiotics with activity against community-associated MRSA, such as trimethoprim-sulfamethoxazole and clindamycin, are preferred empiric therapy for outpatients with cellulitis in the community-associated MRSA-prevalent setting 6.
• The addition of trimethoprim-sulfamethoxazole to cephalexin did not improve outcomes overall or by subgroup in patients diagnosed with cellulitis without abscess 7.

Factors Affecting Treatment

• Patient age, C-reactive protein levels, coexisting diabetes mellitus, and coexisting blood stream infection are associated with longer duration of treatment with intravenous antibiotics for cellulitis 5.
• Therapy with an antibiotic that is not active against community-associated MRSA and severity of cellulitis are factors associated with treatment failure 6.
• Nasal MRSA colonization and purulence at enrollment did not predict treatment response in patients diagnosed with cellulitis without abscess 7.