Directed antibiotic therapy for arthroplasty device infections

When available, the results of culture and susceptibility testing should be used to guide antibiotic therapy for arthroplasty device infections. There is a lack of high-quality randomised controlled trial evidence on which to base antibiotic regimens for arthroplasty device infections and choosing an appropriate antibiotic regimen is complex—seek advice from an infectious diseases physician or clinical microbiologist. The duration of antibiotic therapy depends on the orthopaedic surgical strategy used. Antibiotics are typically administered for a minimum of 6 weeks in patients undergoing exchange arthroplasty and at least 12 weeks in patients undergoing debridement and implant retention (DAIR). For further discussion on duration of antibiotic therapy, see exchange arthroplasty and DAIR.

Prolonged intravenous antibiotic therapy is often thought to be required for arthroplasty device infections; however, evidence suggests early switch to oral therapy is appropriate and avoids the risk of intravascular catheter–associated complications from prolonged intravenous therapyLi, 2019Manning, 2022. The majority of patients should be able to switch to an oral regimen within 7 to 14 days of starting directed therapy. The oral antimicrobials used have good bioavailability (eg amoxicillin, cefalexin, ciprofloxacin, clindamycin, doxycycline, flucloxacillin, moxifloxacin, rifampicin, trimethoprim+sulfamethoxazole) and be able to be given at a high enough dose to achieve adequate exposure at the target site for the relevant organism. Where available, therapeutic drug monitoring is sometimes used in patients at risk of poor oral drug absorption (eg diabetes, chronic kidney disease); see Principles of monitoring antimicrobial therapy for information about the aims of monitoring antimicrobial plasma concentrations.

Prolonged intravenous antibiotic administration may be necessary for patients with Staphylococcus aureus bacteraemia or for the small group of patients in whom there are no suitable oral antibiotics due to patient factors or organism resistance patterns. In carefully selected patients whose condition is stable, ambulatory antimicrobial therapy may be appropriate.

The routine use of oral rifampicin for infection with Gram-positive organisms is controversial—there is no consistent evidence of benefit, and a high rate of adverse effects. For Gram-negative infections, ciprofloxacin is usually the most appropriate oral antibiotic. The recommended dosage is: