Bacteriuria during closed urinary drainage: an evaluation of top-vented versus bag-vented systems

For a 10-month period a top-vented closed urinary drainage system was evaluted and compared to a conventional bag-vented drainage system. The study involved random assignment of either system to all adult patients who required urinary catheterization. Criteria for exclusion included acute or chronic genitourinary tract infection and surgical interference with bladder function. The end point of the study was removal of any part of the system after at least 24 hours or a positive urine culture (greater than 10,000 colonies per ml. urine). The series included 236 patients. Distributions of patient age, sex and hospital service assignment (medical or surgical), antibiotic usage and duration of catheterization were similar in both study groups. Of 113 patients with the top-vented system 16 (14.2 per cent) acquired bacteriuria, whereas 13 of 123 (10.6 per cent) with the bag-drainage system acquired bacteriuria. No significant difference was noted. Antibiotics were used in 202 of 236 patients (86 per cent). Although usage delayed the appearance of bacteriuria in both groups isolates were more frequently yeasts and gram-negative organisms other than Escherichia coli.