What antibiotics are used to treat cellulitis?

From the Guidelines

For the treatment of cellulitis, antibiotics such as cephalexin, dicloxacillin, or clindamycin are commonly prescribed for 5-10 days, with the choice of antibiotic depending on the severity of the infection, local resistance patterns, and patient factors. The most recent and highest quality study, published in 2014 by the Infectious Diseases Society of America 1, recommends that typical cases of cellulitis without systemic signs of infection should receive an antimicrobial agent that is active against streptococci. For patients with systemic signs of infection or those at risk for MRSA, coverage against MRSA should be considered.

• Key considerations in the treatment of cellulitis include:
  • The severity of the infection, with more severe cases requiring intravenous antibiotics and hospitalization
  • Local resistance patterns, with MRSA coverage recommended in areas with high prevalence or in patients with risk factors
  • Patient factors, such as allergies and comorbidities, which can influence the choice of antibiotic
• The recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period, as stated in the 2014 guidelines 1.
• Elevation of the affected area and treatment of predisposing factors, such as edema or underlying cutaneous disorders, are also recommended, as noted in the 2014 guidelines 1.
• Outpatient therapy is recommended for patients who do not have systemic signs of infection, altered mental status, or hemodynamic instability, while hospitalization is recommended for more severe cases or those with poor adherence to therapy, as stated in the 2014 guidelines 1.

From the FDA Drug Label

The cure rates in clinically evaluable patients were 90% in linezolid-treated patients and 85% in oxacillin-treated patients The cure rates by pathogen for microbiologically evaluable patients are presented in Table 18. Table 18 Cure Rates at the Test-of-Cure Visit for Microbiologically Evaluable Adult Patients with Complicated Skin and Skin Structure Infections PathogenCured ZYVOXn/N (%)Oxacillin/Dicloxacillinn/N (%) Staphylococcus aureus73/83 (88)72/84 (86) Methicillin-resistant S aureus2/3 (67)0/0 (-) Streptococcus agalactiae6/6 (100)3/6 (50) Streptococcus pyogenes18/26 (69)21/28 (75)

Antibiotics used to treat cellulitis include:

• Linezolid
• Oxacillin
• Vancomycin
• Ampicillin/sulbactam
• Amoxicillin/clavulanate Key points:
• Linezolid and oxacillin have cure rates of 90% and 85%, respectively, in clinically evaluable patients with complicated skin and skin structure infections.
• The cure rates for linezolid-treated patients with specific pathogens are: 88% for Staphylococcus aureus, 67% for Methicillin-resistant S aureus, 100% for Streptococcus agalactiae, and 69% for Streptococcus pyogenes. 2

From the Research

Antibiotics for Cellulitis

• The following antibiotics have been studied for the treatment of cellulitis:
  • Linezolid and rifampin combination therapy may be an alternative therapeutic option for cutaneous MRSA infections that respond poorly to vancomycin 3
  • Trimethoprim-sulfamethoxazole, cephalexin, and clindamycin are commonly prescribed antibiotics for cellulitis, with trimethoprim-sulfamethoxazole having a higher treatment success rate than cephalexin 4
  • Flucloxacillin monotherapy and flucloxacillin/phenoxymethylpenicillin dual therapy are being compared in the PEDOCELL trial for the outpatient treatment of cellulitis 5
  • Levofloxacin has been studied for the treatment of uncomplicated cellulitis, with 5 days of therapy appearing to be as effective as 10 days of therapy 6
  • The route of antibiotic administration (IV or PO) and duration of treatment do not appear to be associated with clinical outcome in patients with cellulitis 7

Specific Antibiotics and Their Uses

• Linezolid and rifampin: for cutaneous MRSA infections that respond poorly to vancomycin 3
• Trimethoprim-sulfamethoxazole: for empiric outpatient therapy of cellulitis, especially in areas with a high prevalence of community-associated MRSA infections 4
• Cephalexin: for empiric outpatient therapy of cellulitis, although it may have a lower treatment success rate than trimethoprim-sulfamethoxazole 4
• Clindamycin: for empiric outpatient therapy of cellulitis, especially in patients with MRSA infections or moderately severe cellulitis 4
• Flucloxacillin: for the outpatient treatment of cellulitis, with monotherapy and dual therapy with phenoxymethylpenicillin being compared in the PEDOCELL trial 5
• Levofloxacin: for the treatment of uncomplicated cellulitis, with 5 days of therapy appearing to be as effective as 10 days of therapy 6