Patients will be randomly assigned to low dosage (10 mg/kg/j) rifampicin group or high dosage (20 mg/kg/j) rifampicin group. Rifampicin treatment will be prescribed in association with another antibiotic chosen by investigator according to the antibiogram results. Association with fluoroquinolones is the first choice combination, if it is possible. The global antibiotic treatment duration depends on the investigator's choice.