Cellulitis Treatment Guidelines

Pathogen Considerations

Cellulitis is primarily caused by beta-hemolytic streptococci, with Staphylococcus aureus less frequently involved unless associated with penetrating trauma or an underlying abscess 1
In Southern California, where community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) prevalence is high, consider MRSA coverage for specific risk factors 2

For typical cases of cellulitis, treatment should begin with an antimicrobial agent that is active against streptococci, such as penicillin, amoxicillin, dicloxacillin, cephalexin, or clindamycin for 5 days 3, 4
First-line therapy for mild cellulitis includes oral antibiotics active against streptococci, with options such as penicillin, amoxicillin, dicloxacillin, or cephalexin 4, 5
For penicillin allergy, clindamycin or erythromycin are recommended 1
For moderate cellulitis, treatment options include systemic antibiotics with coverage for streptococci and consideration of adding coverage against methicillin-susceptible S. aureus (MSSA) 3, 4
For severe cellulitis or high-risk patients, indications for MRSA coverage include penetrating trauma, evidence of MRSA elsewhere, nasal colonization with MRSA, injection drug use, purulent drainage, or SIRS 4, 5
Treatment options for severe cellulitis include vancomycin or another antimicrobial effective against both MRSA and streptococci, and for severely compromised patients, vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 4, 6

Cultures of blood or cutaneous aspirates are not routinely recommended for typical cases 3, 4
Blood cultures should be obtained in patients with malignancy, severe systemic features, or unusual predisposing factors 4, 5

Elevate the affected area to promote gravity drainage of edema and inflammatory substances 4, 1
Treat predisposing conditions such as edema, tinea pedis, or other toe web abnormalities 4, 6
Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adult patients to hasten resolution 4, 5

Identify and treat predisposing conditions such as edema, obesity, venous insufficiency, and toe web abnormalities 4, 5
For patients with 3-4 episodes per year despite addressing predisposing factors, consider prophylactic antibiotics such as oral penicillin or erythromycin twice daily for 4-52 weeks 4, 6

Failure to examine interdigital toe spaces for fissuring, scaling, or maceration that may harbor pathogens 4, 6
Not elevating the affected area, which delays improvement 1
Inadequate treatment duration when clinical improvement is not evident after 5 days 4, 6

The American College of Physicians recommends a 5- to 6-day course of antibiotics active against streptococci for nonpurulent cellulitis 7, 8
The National Institute for Health and Care Excellence guideline recommends a course of 5 to 7 days for cellulitis treatment 7
Multiple studies support the efficacy of short-course therapy for cellulitis, with similar clinical outcomes between shorter and longer treatment durations 9, 10

Levofloxacin is a viable alternative for patients with penicillin allergy 7
Fluoroquinolones, including levofloxacin, should be reserved for patients with allergies to beta-lactams or in specific clinical scenarios 11
For cellulitis associated with certain high-risk conditions, additional coverage for MRSA may be necessary 7

The American College of Physicians recommends empirical therapy for non-purulent cellulitis with antibiotics active against beta-hemolytic streptococci, such as penicillin, amoxicillin, dicloxacillin, or cephalexin for 5 days, with extension if no improvement is seen 12
For typical non-purulent cellulitis, first-line therapy should target streptococci with options including amoxicillin, as recommended by the Infectious Diseases Society of America 13

For complicated skin and skin structure infections requiring hospitalization, empirical therapy for MRSA should be considered pending culture data, with options including IV vancomycin, oral or IV linezolid, daptomycin, telavancin, or clindamycin, as suggested by the Infectious Diseases Society of America 13
The duration of treatment for severe cellulitis is 7-14 days, individualized based on clinical response, according to the Infectious Diseases Society of America 13

If coverage for both beta-hemolytic streptococci and CA-MRSA is desired, options include clindamycin alone, or TMP-SMX or a tetracycline in combination with a beta-lactam, such as amoxicillin, as recommended by the Infectious Diseases Society of America 13