The impact of Boric Acid tubes on quantitative urinary bacterial cultures in hospitalized patients

TL;DR

This study shows that using boric acid tubes for urine collection reduces bacterial culture positivity in samples processed within 4–24 hours, improving diagnostic accuracy.

Contribution

Demonstrates the effectiveness of boric acid tubes in reducing false positives in urine cultures for hospitalized patients.

Findings

Culture positivity decreased from 30.4% to 24.0% for 4–24-hour processed samples after using boric acid tubes.

The intervention significantly reduced positivity only in the 4–24-hour processing window (OR 0.80, 95% CI 0.67–0.94).

No significant changes were observed in specimens processed in <4 or ≥24 hours.

Abstract

The accuracy of urine culture results can be affected by pre-analytical factors such as transport delays and storage conditions. The objectives of this study were to analyze urine collection practices and assess the impact of introducing boric acid tubes for urine collection on quantitative urinary bacterial cultures of hospitalized patients in medical wards.

A quasi-experimental pre-post study conducted in an acute care facility. In the pre-intervention phase (2020–2021), urine samples were transported without preservatives at room temperature. In 2022 (post-intervention), we transitioned to boric acid transport tubes, evaluating its effect on significant bacterial growth (≥ 105 CFU/ml). Bivariate and multivariate analyses identified predictors of culture positivity.

Throughout the duration of the study, a total of 12,660 urine cultures were analyzed. Date and time documentation was complete for 38.3% of specimens. Culture positivity was higher with longer processing times: positivity was 21.3% (220/1034) when specimens were processed within 4 h, 28.4% (955/3364) when processed in 4–24 h, and 32.9% (137/417) when processed after 24 h (p < 0.0001). For 4-24-hour processing, positivity decreased from 30.4% (704/2317) pre-intervention to 24.0% (251/1047) post-intervention (p < 0.001), with no significant changes in < 4 or ≥ 24-hour specimens. Stratified analysis by processing time revealed that the intervention was associated with reduced positivity only in cultures processed within 4–24 h (OR 0.80, 95% CI 0.67–0.94; p = 0.008).

The introduction of boric acid transport tubes predominantly influenced cultures transported within a 4–24-hour window. This presents an opportunity to improve urine tract infection diagnostic practices in healthcare settings.

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