As early as 1955, Kass66 demonstrated the value of prophylactic antibiotic drug therapy in catheterized patients. Because receiving systemic antibiotic drug therapy has been shown repeatedly to lower the risk for developing a UTI in catheterized patients,8,17,18,67 several investigators have studied this intervention. Most studies of the past 15 years have used fluoroquinolone agents. Study designs were often retrospective, with variable inclusion criteria. Comparing results of these studies is further hampered by differences in definitions of UTI, timing and duration of antibiotic agents used, and outcomes measured. Studies with short-term catheterization were mainly in postoperative patients, whereas those with long-term catheters were largely in nursing home residents. Trials that randomized previously catheterized patients to either antibacterial drug prophylaxis or placebo yielded mixed results. In patient groups given prophylaxis at or shortly after catheter insertion, however, the efficacy was more convincing. When examined, low doses of antibiotic drugs were as effective as higher doses.21 In general, systemic antibiotic drug therapy tends to be most useful in patients requiring urinary catheterization for 3 to 14 days.21,68- 73 Those catheterized for shorter durations are not at high enough risk for UTI, and those with longer durations develop bacteriuria whether treated or not. Most experts do not recommend routinely using prophylactic antibiotic medications for catheterized patients because of their cost, potential adverse effects, and role in encouraging antibiotic drug resistance.40,74 Results of several studies21,69,73 demonstrate that antibiotic drug prophylaxis increased the rate of isolation of resistant organisms. Prophylactic antibiotic drug therapy may, however, be appropriate in those who require relatively short-term catheterization and are at high risk for complications from a UTI.75,76 Most hospitalized patients—especially those in intensive care units—are already receiving antibiotic drug therapy for other reasons. The summary by Beeson2(p3) 4 decades ago of the value of systemic antibiotic drug therapy in patients with a long-term indwelling catheter still holds: ". . . chemoprophylaxis could not be expected to, and indeed does not, do anything but eradicate susceptible organisms and favor the establishment of an infection more difficult to treat."