Inclusion Criteria:  Diagnosed with recurrent cystitis including 2 times of rUTI within the last 6 months or 3 times in the last 12 months, where at least 2 cultures show the same bacteria. Normal investigation for lower urinary tract diseases (LUTD) including voiding diary, symptom scores, flexible cystoscopy, voiding diagram and test for residual urine. Failed previously treatments. Patients with native bladder with both spontaneous voiding, the need for clean intermittent catheter (CIC) or indwelling catheter. Patients with neurogenic and non-neurogenic bladder dysfunction. Patients with urostomy, kidney transplantation or another complicated genesis. Written consent.  Exclusion Criteria:  Malignancy in the urinary tract, kidney-, ureteral- or bladder stones, age < 18 years, pregnancy, breastfeeding. Patients in ongoing orally antibiotic treatment. Not able to speak or understand Danish.