Effectiveness of an Antimicrobial Stewardship Approach for Urinary Catheter-Associated Asymptomatic Bacteriuria

Abstract

Importance: Overtreatment of asymptomatic bacteriuria (ASB) in patients with urinary catheters remains high. Health care professionals have difficulty differentiating cases of ASB from catheter-associated urinary tract infections.

Objectives: To evaluate the effectiveness and sustainability of an intervention to reduce urine culture ordering and antimicrobial prescribing for catheter-associated ASB compared with standard quality improvement methods.

Design, setting, and participants: A preintervention and postintervention comparison with a contemporaneous control group from July 2010 to June 2013 at 2 Veterans Affairs health care systems. Study populations were patients with urinary catheters on acute medicine wards and long-term care units and health care professionals who order urine cultures and prescribe antimicrobials.

Intervention: A multifaceted guidelines implementation intervention.

Main outcomes and measures: The primary outcomes were urine cultures ordered per 1000 bed-days and cases of ASB receiving antibiotics (overtreatment) during intervention and maintenance periods compared with baseline at both sites. Patient-level analysis of inappropriate antimicrobial use adjusted for individual covariates.

Results: Study surveillance included 289,754 total bed-days. The overall rate of urine culture ordering decreased significantly during the intervention period (from 41.2 to 23.3 per 1000 bed-days; incidence rate ration [IRR], 0.57; 95% CI, 0.53-0.61) and further during the maintenance period (to 12.0 per 1000 bed-days; IRR, 0.29; 95% CI, 0.26-0.32) (P < .001 for both). At the comparison site, urine cultures ordered did not change significantly across all 3 periods. There was a significant difference in the number of urine cultures ordered per month over time when comparing the 2 sites using longitudinal linear regression (P < .001). Overtreatment of ASB at the intervention site fell significantly during the intervention period (from 1.6 to 0.6 per 1000 bed-days; IRR, 0.35; 95% CI, 0.22-0.55), and these reductions persisted during the maintenance period (to 0.4 per 1000 bed-days; IRR, 0.24; 95% CI, 0.13-0.42) (P < .001 for both). Overtreatment of ASB at the comparison site was similar across all periods (odds ratio, 1.32; 95% CI, 0.69-2.52). When analyzed by type of ward, the decrease in ASB overtreatment was significant in long-term care.

Conclusions and relevance: A multifaceted intervention targeting health care professionals who diagnose and treat patients with urinary catheters reduced overtreatment of ASB compared with standard quality improvement methods. These improvements persisted during a low-intensity maintenance period. The impact was more pronounced in long-term care, an emerging domain for antimicrobial stewardship.