Effect of Perineal Cleansing on Contamination Rate of Mid-stream Urine Culture

Abstract 

Study Objective

Urinary tract infection (UTI) and chlamydial or gonococcal urethritis are the most common causes of female dysuria. While chlamydia and gonorrhea can be detected with a nucleic acid amplification test performed on an uncleansed first part voided urine sample, urine cultures to test for UTI require a mid-stream clean caught sample. In order to determine whether collecting two sequential non-clean caught urine samples during the same void to test for chlamydia, gonorrhea, and UTI is a reasonable approach, we assessed the degree to which perineal cleansing reduces bacterial contamination of mid-stream urine cultures.

Design

Experimental study comparing mid-stream urine samples collected with (n = 25) and without (n = 25) perineal cleansing.

Setting

A university-based adolescent clinic

Participants

We recruited fifty 14–23-year-old (mean 18.5 yrs, SD 2.3) asymptomatic females.

Main Outcome Measure

Perineal flora contamination rate of mid-stream urine cultures collected with and without perineal cleansing.

Results

No culture grew >10⁴ colonies of a pathogenic bacterium. Eleven (44%) of the experimental group samples and 9 (36%) of the control samples grew >10⁴ colonies of perineal bacterial flora (χ² = .33, P = 0.56). Participants' previous experience collecting mid-stream urine was not associated with less bacterial contamination.

Conclusions

Among this small sample of asymptomatic young women, perineal cleansing did not significantly reduce perineal flora contamination of mid-stream urine cultures. If larger studies of symptomatic young women replicate these findings, young women could collect two sequential urine samples from the same void to test for chlamydia, gonorrhea, and UTI.

Key Words: Mid-stream urine collection, Perineal cleansing, Chlamydia, Gonorrhea, Nucleic acid amplification test (NAAT), Urinary tract infection