Background Antibiotic-resistant bacteria are a major public health problem throughout the world. In 2006, in accordance with the national guidelines for antibiotic use, the CHRU of Nancy created an operational multidisciplinary antibiotic team at one of its sites. In 2011, a cluster-controlled trial showed that the operational multidisciplinary antibiotic team (the intervention) had a favourable short-term effect on antibiotic use and costs. Objective Our objective was to determine whether these effects continued over the medium to long term (that is, 2-7 years after creation of the operational multidisciplinary antibiotic team, 2009-2014). Setting The 1800-bed University Hospital of Nancy (France). Method The effect in the medium to long term is measured according to the same criteria and assessed by the same methods as the first study. A cluster controlled trial was performed on the period 2009-2014. The intervention group comprised 11 medical and surgical wards in settings where the operational multidisciplinary antibiotic team was implemented and the control group comprised 6 wards without this operational team. Main outcome measure Consumption of antibiotics overall and by therapeutic class (in defined daily doses per 1000 patient-days) and costs savings (in €). Results The reduction in antibiotic use and costs continued, but at a lower rate than in the short term (11% between 2009 and 2014 compared with 33% between 2007 and 2009) at the site of the intervention. The principal decreases concerned fluoroquinolones and glycopeptides. At the site without an operational multidisciplinary antibiotic team (the control group), total antibiotic use remained stable. Between 2009 and 2014, costs fell 10.5% in the intervention group and 5.7% in the control group. Conclusion This study shows that it is possible to maintain the effectiveness over time of such an intervention and demonstrates its role in defining a hospital's antibiotic policy.