Introduction - Retrograde biliary catheterization is a procedure associated with a risk of infection. We report an outbreak caused by Klebsiella pneumoniae producing a CTX-M-15-type extended-spectrum beta-lactamase (KpCTXM). Patients and Methods - The alert was issued by the Bacteriology Laboratory at Clermont-Ferrand University Hospital. Our investigations and root cause analysis included observation of retrograde catheterization procedures and duodenoscope reprocessing protocols, review of examination schedules, and environmental and equipment sampling; four external reports were filed. Results - Between December 2008 and August 2009, 16 KpCTXM infections or colonizations were identified, including 8 bacteremias, 4 biliary infections, and 4 gastrointestinal colonizations. All patients had undergone one or more retrograde catheterizations. The epidemic strain was found on a duodenoscope. The root cause analysis revealed anomalies in the handling of the device and organizational issues. Conclusion - The outbreak was linked to the contamination of duodenoscopes with non-detachable heads of the TJF145 type. Following the root cause analysis, corrective measures for endoscope processing were proposed, along with a new protocol for performing retrograde catheterization. No new cases of contamination have been observed in the past 16 months. A national alert was issued by the French Health Products Safety Agency (Afssaps) to users of TJF145-type endoscopes. (R.A.)