Two hundred consecutive patients with bladder cancer seen as outpatients in the urology department at Memorial Sloan-Kettering Cancer Center by 1 surgeon between January 1, 2009, and December 31, 2010, were eligible. All agreed to participate and provided oral informed consent. None was febrile or had symptoms of a urinary tract infection (UTI). On the first day of treatment, each patient submitted a clean-catch voided urine sample for bacteriologic studies. Patients then underwent instillations of BCG through a small urethral catheter once a week for 6 weeks and did not receive antibiotics. Patients were monitored each week during treatments and then weekly by telephone. Febrile UTI was defined as fever 102°F or greater and a positive urine culture. After the first culture, no further urine cultures were obtained unless prompted by fever and symptoms. At 3 months, patients were evaluated for response to BCG by cystoscopy and biopsy. The sample size was based on a projected proportion of at least 20% of patients with bacteriuria,1 and at least 5% developing a UTI, with no difference between infected and uninfected patients. χ2 test was used to test the correlation of bacteriuria with the frequency of UTI and response to BCG therapy, with a 2-sided significance level of .05. Data analyses were conducted using SPSS version 19 (SPSS Inc, Chicago, Illinois). The study was approved by the hospital's institutional review board.