From the Guidelines
For cellulitis of the right lower extremity (RLE) in a patient with a history of total knee arthroplasty (TKA), the recommended oral antibiotic is cefadroxil 500mg orally twice daily for 5-7 days, as it provides coverage against streptococci and Staphylococcus species, which are the most common pathogens in cellulitis 1. If the patient has a penicillin allergy, clindamycin 300-450mg orally four times daily is an appropriate alternative. Since this patient has a prosthetic joint (status post TKA), coverage for methicillin-resistant Staphylococcus aureus (MRSA) should be considered, in which case trimethoprim-sulfamethoxazole (TMP-SMX) DS 1-2 tablets twice daily or doxycycline 100mg twice daily may be used 1. The duration of therapy should be 5 days, but treatment should be extended if the infection has not improved within this time period, with longer courses often needed for post-surgical infections 1. Close monitoring for improvement is essential, and if symptoms worsen or fail to improve within 48-72 hours, the patient should be reevaluated for possible surgical intervention or intravenous antibiotics. Key considerations in managing cellulitis include:
- Elevation of the affected area to promote gravity drainage of edema and inflammatory substances
- Treatment of predisposing factors, such as edema or underlying cutaneous disorders
- Examination of the interdigital toe spaces for signs of infection or colonization with pathogens
- Use of systemic corticosteroids as an optional adjunct for treatment of uncomplicated cellulitis and erysipelas in selected adult patients 1. The choice of antibiotic targets the most common pathogens in cellulitis while considering the presence of prosthetic material, which increases the risk of biofilm formation and treatment failure. In cases where the patient has a history of recurrent cellulitis, prophylactic antibiotics may be considered, with options including monthly intramuscular benzathine penicillin injections or oral therapy with erythromycin or penicillin V 1.
From the FDA Drug Label
Skin and Skin Structure Infections: Due to S. aureus (including beta-lactamase-producing strains), S. pyogenes, and other strains of streptococci. The FDA drug label does not answer the question.
From the Research
PO Antibiotic for RLE Cellulitis
The most common bacteria causing cellulitis are Staphylococcus aureus, Streptococcus pyogenes, and other β-hemolytic streptococci 2.
- Treatment for cellulitis typically involves a penicillin or cephalosporin 2.
- For patients with a history of total knee arthroplasty (TKA), the treatment of acute hematogenous infections following TKA with the treatment of irrigation, debridement, and retention of the prosthetic components has been reported 3.
- The most sensitive antibiotics were injected into the irrigation saline, but the specific PO antibiotic is not mentioned in the study 3.
Considerations for TKA Patients
- TKA appears to predispose to acute bacterial skin and soft tissue infections (ABSSTIs) in the ipsilateral lower extremity often years after the procedure, particularly in the absence of other local factors 4.
- Gram-positive coccus and Staphylococcus coagulase-negative and Staphylococcus aureus are the most common isolated germs (>50% of the cases) in infection after total knee replacement 5.
- Conditions related to the patient, to the surgical procedure, and even to the post-op have been identified as risk factors to infection after total knee replacement 5.
Antibiotic Treatment
- The high failure rate of debridement and component retention suggests that immediate component removal should be considered in the presence of acute S. aureus infection in total knee arthroplasty 6.
- Patients who developed an acute hematogenous infection with non-staphylococcus species following operative debridement and continuous irrigation with prosthetic retention had satisfactory outcomes, but patients infected with staphylococcal had poor results 3.