Résumé : Background: Enhanced oral (po) bioavailability of antimicrobial drugs allows conversion to po therapy once a patient meets defined clinical criteria. This can reduce length of hospital stay, healthcare costs and risk of complications related to intravenous (iv) access. We developed a quality indicator for assessing the appropriate iv-to-po switch of bioavailable antibiotics and evaluated its feasibility and clinical relevance across acute healthcare systems. Methods: The study was designed as a multicentre, multinational observational audit. The indicator was the proportion of inappropriate iv treatments at any point in time in adult patients treated with fluoroquinolones, clindamycin, linezolid or metronidazole. Treatments were prospectively evaluated by a trained physician or clinical pharmacist using predefined clinical criteria. The feasibility of the indicator was evaluated by measuring data availability, data collection workload and sensitivity to improvement. Results: Data were collected over a 3 month period in five university hospitals in Austria, Belgium and Germany and iv treatment was assessed in 211 patients. The indicator was measurable in 99.1% of cases. By intention-to-treat analysis, 37.0% (95% CI 30.5-43.9) of treatments were inappropriate, ranging from 17.5% to 53.8% across hospitals. The median time needed for case assessment and documentation was 29 min. Conclusions: This quality indicator was found to be generally feasible in hospitals across three European countries, and informative about the local need for clinical quality improvement. © The Author 2012. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.