What are the appropriate inpatient antibiotics (abx) for the treatment of cellulitis?

From the Guidelines

For inpatient treatment of cellulitis, empiric intravenous antibiotics should target both streptococci and Staphylococcus aureus, with first-line options including cefazolin 1-2g IV every 8 hours or oxacillin/nafcillin 1-2g IV every 4-6 hours, as recommended by the Infectious Diseases Society of America 1. When considering the treatment of cellulitis, it is crucial to prioritize the coverage of both streptococci and Staphylococcus aureus. The choice of antibiotic should be guided by the severity of the infection, the presence of systemic symptoms, and the potential for methicillin-resistant Staphylococcus aureus (MRSA) involvement.

• For patients without a history of MRSA or severe infection, cefazolin or oxacillin/nafcillin are appropriate choices, given their efficacy against streptococci and methicillin-susceptible Staphylococcus aureus (MSSA) 1.
• If MRSA is suspected, vancomycin 15-20 mg/kg IV every 8-12 hours (adjusted based on levels and renal function) or daptomycin 4-6 mg/kg IV daily are recommended as first-line options 1.
• For patients with beta-lactam allergies, clindamycin 600-900mg IV every 8 hours can be used if the local MRSA resistance rate is low, as it provides coverage against both streptococci and MRSA 1.
• The duration of treatment typically ranges from 5-14 days, depending on the clinical response, with the goal of switching to oral antibiotics when the patient shows clinical improvement, is afebrile for 24-48 hours, and inflammatory markers are trending down 1.
• Common oral step-down options include cephalexin 500mg four times daily, dicloxacillin 500mg four times daily, or clindamycin 300-450mg three times daily for non-MRSA coverage, and trimethoprim-sulfamethoxazole DS twice daily or doxycycline 100mg twice daily for MRSA coverage 1.
• Adjunctive measures such as elevating the affected limb, managing underlying conditions like edema or tinea, and ensuring adequate pain control are also important during treatment.

From the FDA Drug Label

The two trials were similar in design but differed in patient characteristics, including history of diabetes and peripheral vascular disease. There were a total of 534 adult patients treated with daptomycin for injection and 558 treated with comparator in the two trials. The majority (89. 7%) of patients received IV medication exclusively. The efficacy endpoints in both trials were the clinical success rates in the intent-to-treat (ITT) population and in the clinically evaluable (CE) population. Patients could switch to oral therapy after a minimum of 4 days of IV treatment if clinical improvement was demonstrated. Comparator: vancomycin (1 g IV q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin, oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g/day IV in divided doses).

The appropriate inpatient antibiotics for the treatment of cellulitis include:

• Vancomycin (1 g IV q12h)
• Anti-staphylococcal semi-synthetic penicillins (i.e., nafcillin, oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g/day IV in divided doses) 2

From the Research

Appropriate Inpatient Antibiotics for Cellulitis

• The treatment of cellulitis often involves the use of antibiotics that are effective against Staphylococcus aureus and Streptococcus species 3, 4.
• For methicillin-susceptible Staphylococcus aureus (MSSA) infections, penicillinase-resistant penicillins (flucloxacillin, dicloxacillin) are the antibiotics of choice, while first-generation cephalosporins (cefazolin, cephalothin, and cephalexin) can be used for less serious infections or in patients with penicillin hypersensitivity 3.
• Ceftriaxone has been shown to be a viable alternative for the treatment of MSSA bloodstream infections, with once-daily dosing and a short infusion time 5, 6.
• A study comparing cefazolin plus probenecid with ceftriaxone plus placebo for the treatment of moderate-to-severe cellulitis found that both regimens were effective, with clinical cure rates of 86% and 96%, respectively 7.
• For methicillin-resistant Staphylococcus aureus (MRSA) infections, vancomycin or teicoplanin are commonly used, while lincosamides (clindamycin, lincomycin) or cotrimoxazole can be used for less serious infections 3, 4.

Specific Antibiotic Options

• Cefazolin: a first-generation cephalosporin that can be used for MSSA infections, particularly for skin and soft tissue infections 3, 7.
• Ceftriaxone: a third-generation cephalosporin that can be used for MSSA bloodstream infections, with once-daily dosing and a short infusion time 5, 6.
• Vancomycin: a glycopeptide antibiotic that is commonly used for MRSA infections, particularly for severe infections 3, 4.
• Clindamycin: a lincosamide antibiotic that can be used for less serious MRSA infections, such as skin and soft tissue infections 3, 4.