Efficacy of 7 Days Versus 14 Days of Antibiotic Therapy for Acute Pyelonephritis in Kidney Transplant Recipients, a Multicentre Randomized Non-inferiority Trial.

Inclusion Criteria: * Age \>18 years KTR * APN defined by: fever (T°≥38°C) (with or without clinical signs and/or symptoms of UTI) and pyuria (≥10\^4 white blood cells/mL or ≥10/mm3) and positive urine culture (uropathogen ≥10\^3 CFU/mL susceptible to the empirically administrated antibiotic) * No confirmed or suspected febrile non urinary bacterial infection * No urologic/renal complication at baseline imaging (abscess, obstruction...) * Favourable early response to antibiotic treatment:48 to 60 hours after the first dose of antibiotic effective against the causative uropathogen) defined by: T°\<38°C and improvement (or resolution) of signs and/or symptoms of urinary tract infection if present at diagnosis * Written informed consent Exclusion Criteria: * Severe or complicated condition * Any rapidly progressing disease or immediately life-threatening illness, including, but not limited to, septic shock, current or impeding respiratory failure, acute heart or liver failure * Admission or stay in intensive care unit at baseline * Obstruction of the urinary tract * Renal, perinephric or prostatic abscess * Prior inclusion in this study * Current participation to another interventional study * Dual antibiotic therapy (prophylactic antibiotic such as cotrimoxazole allowed) (only 1 dose of aminoside is allowed before randomization) * First month post transplantation * Current indwelling catheter (including bladder catheter, ureteral stents, percutaneous nephrostomy tubes) * Neurogenic bladder * Enterocystoplasty * Immunodeficiency or immunosuppressive therapy not related to kidney transplantation including hematologic malignancy, cancer, asplenia, neutropenia\<500 neutrophils/mm3 * Pregnancy, breastfeeding * Hypersensitivity or previous severe adverse drug reaction to the antibiotic therapy * Unable or unwilling, in the judgment of the investigator, to comply with the protocol * Life expectancy\<1 month * Patient under legal guardianship or without healthcare coverage * Homeless patient * Women with childbearing potential not using adequate contraception