What is the recommended initial antibiotic therapy for a patient diagnosed with septic arthritis?

Initial antibiotic therapy for septic arthritis should be prompt and empiric, targeting the most common causative organisms, primarily Staphylococcus aureus and Streptococci. In the UK, first-line treatment typically involves intravenous administration of a beta-lactam antibiotic such as flucloxacillin, which is effective against beta-lactamase-producing staphylococci and streptococci. For patients allergic to penicillin, a macrolide such as clarithromycin or erythromycin may be used as an oral alternative. The choice of antibiotic should be guided by local antimicrobial policies and adjusted according to microbiological culture and sensitivity results once available NICE CKS.

In cases where methicillin-resistant Staphylococcus aureus (MRSA) is suspected or confirmed, treatment may require intravenous vancomycin or teicoplanin, with alternatives like daptomycin considered if necessary NICE CKS. The initial intravenous route is preferred to ensure adequate tissue penetration and rapid control of infection, especially in systemically unwell patients or those with comorbidities NICE CKS.

Empiric therapy should be reviewed and narrowed based on culture results to reduce antimicrobial resistance risk, consistent with NICE antimicrobial stewardship guidelines NICE NG51. The duration of antibiotic therapy is generally at least 2 weeks but may extend depending on clinical response and specialist advice NICE CKS; literature supports early and aggressive treatment to prevent joint destruction and systemic complications Hassan et al. 2017.