What is the diagnosis and treatment for cellulitis?

From the Guidelines

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

Key Considerations

• The choice of antibiotic depends on the severity of the infection, with oral antibiotics like cephalexin, dicloxacillin, or amoxicillin-clavulanate suitable for mild cases, and intravenous antibiotics like cefazolin, nafcillin, or vancomycin necessary for more severe cases requiring hospitalization.
• Elevation of the affected area, pain management, and keeping the area clean and dry are also important aspects of treatment.
• Patients with systemic signs of infection, severe immunocompromisation, or other complicating factors may require broader-spectrum antimicrobial coverage or longer treatment durations.

Treatment Options

• Oral antibiotics:
  • Cephalexin (500 mg four times daily)
  • Dicloxacillin (500 mg four times daily)
  • Amoxicillin-clavulanate (875/125 mg twice daily)
• Intravenous antibiotics:
  • Cefazolin
  • Nafcillin
  • Vancomycin

Prevention of Recurrences

• Treating interdigital maceration and keeping the skin well hydrated with emollients can help reduce the risk of recurrent cellulitis.
• Prophylactic antibiotics may be considered for patients with frequent infections, with options including monthly intramuscular benzathine penicillin injections or oral therapy with erythromycin or penicillin V 1.

Important Notes

• Cellulitis can lead to serious complications if left untreated, including abscess formation, tissue damage, or bloodstream infection.
• Patients should seek immediate medical attention if they develop fever, increasing pain or redness, or if the affected area develops streaking.

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.

The types of ABSSSI included were cellulitis/erysipelas (41%), wound infection (29%), and major cutaneous abscess (30%) The types of ABSSSI included were cellulitis/erysipelas (50%), wound infection (30%), and major cutaneous abscess (20%)

The drug tedizolid (PO) was studied in patients with cellulitis/erysipelas, among other conditions.

• The percentage of patients with cellulitis/erysipelas in the two trials were 41% and 50%. The study does not provide information on the effectiveness of tedizolid (PO) specifically for cellulitis. 2

From the Research

Treatment of Cellulitis

• The treatment of cellulitis can be done using oral or parenteral antimicrobials, with studies showing that oral antimicrobials are as effective as parenteral antimicrobials for the treatment of uncomplicated cellulitis 3.
• A study found that patients who received oral antimicrobials had a shorter mean time to no advancement of cellulitis compared to those who received parenteral antimicrobials, with a mean difference of -0.49 days 3.
• Another study found that patients who received only oral therapy were more likely to have improved at day 5 compared to those who received at least a single dose of intravenous therapy, and were as likely to be back to their normal activities at day 10 and day 30 4.

Antibiotic Route and Duration of Therapy

• A study found that the route of antibiotic administration (oral or intravenous) did not affect the clinical outcome of patients with cellulitis, and that a course length of more than 5 days did not result in any additional benefit 4.
• A systematic review and meta-analysis found that there was no evidence to support the superiority of any one antibiotic over another, and that antibiotics with activity against methicillin-resistant Staphylococcus aureus did not add an advantage 5.
• The same review found that the use of intravenous antibiotics over oral antibiotics and treatment duration of longer than 5 days were not supported by evidence 5.

Combination Antibiotic and Anti-Inflammatory Therapy

• A pilot study found that the addition of oral nonsteroidal anti-inflammatory therapy to antibiotic treatment hastened the resolution of cellulitis-related inflammation, with 82.8% of patients showing regression of inflammation within 1 to 2 days 6.
• The study also found that all patients receiving adjunctive anti-inflammatory treatment experienced complete resolution of cellulitis in 4 to 5 days or less, compared to 24.2% of patients treated with antibiotic alone who required 6 to 7 days or more 6.

Empiric Outpatient Therapy

• A retrospective cohort study found that trimethoprim-sulfamethoxazole had a higher treatment success rate compared to cephalexin for empiric outpatient therapy of cellulitis, especially in areas with a high prevalence of community-associated methicillin-resistant Staphylococcus aureus infections 7.
• The study also found that clindamycin had higher success rates compared to cephalexin in patients with culture-confirmed MRSA infections, moderately severe cellulitis, and obesity 7.