Contamination in Adult Midstream Clean-Catch Urine Cultures in the Emergency Department: A Randomized Controlled...

A midstream clean-catch urine sample is recommended to obtain a urine culture in symptomatic adults with suspected urinary tract infection. The aim of this randomized controlled trial was to determine whether a novel funnel urine-collection system combined with a silver-colloidal cleaning wipe would decrease mixed flora contamination in midstream clean-catch urine cultures from ambulatory adults in the emergency department.

In a 2x2 factorial trial, adult participants were randomized to 4 groups: (A) sterile screw-top urine collection container/cup paired with a castile-soap wipe (control group); (B) sterile screw-top urine collection container/cup paired with a colloidal silver-impregnated wipe; (C) sterile urine-collection funnel paired with a castile-soap wipe; (D) sterile urine-collection funnel paired with a colloidal silver-impregnated wipe.

The trial was stopped after interim analysis, as the contamination rate in the control group (30%) was markedly lower than the historical ED contamination rate (40%) at the study site. From 1,112 urinalysis results, 223 urine culture results were analyzed (190 female patients and 33 male patients). Urine contamination rates were as follows: Group A, n = 67 (29.9% contaminated); Group B, n = 69 (34.8% contaminated); Group C, n = 51 (23.5% contaminated); Group D, n = 36 (22.2% contaminated). The differences in contamination rates were not statistically different among any of the groups.

The use of a funnel urine-collection system and silver-impregnated wipe did not reduce urine-culture contamination in adult midstream clean-catch urine cultures in the emergency department.