The Orthopaedic Service of the Geneva University Hospitals engages dedicated infectious disease (ID) specialists to assist in the treatment of infected patients. We investigated the daily clinical activity and the impact on antibiotic costs in the Septic Unit since 2000. METHODS: Retrospective analysis of various databases. Prospective survey of clinical activity from January 2008 to March 2008. RESULTS: According to the survey, the ID specialist performed 265 first-time and 1420 follow-up consultations (average of 11.4 consultations per working day). In 88% of cases the antibiotic regimen initiated by the surgeons was approved. When the ID specialist had to change antibiotic treatment, it was for de-escalation in 43.7%, discontinuance in 32.4%, and initiation in 24.4% of cases. From April 2007 to March 2008, the ID specialist decreased total antibiotic use by 43 DDD/100 patients-days (p=0.0006) in the Septic Unit. Direct antibiotic costs decreased by US $64,380 over the same period, equal to the annual salary of the ID specialist. There was no change in the number of recurrent infections. CONCLUSIONS: The main antibiotic-related activity of the dedicated orthopaedic ID specialist in Geneva our institution was to discontinue or adjust a pre-existing antimicrobial therapy. This activity significantly reduced antibiotic use and related costs on a septic orthopaedic unit.