A new study has examined the limitations of the current definition of asymptomatic bacteriuria (ASB) in antimicrobial stewardship and revealed that asymptomatic pyuria and/or nitrituria (ASPN) could serve as a more comprehensive marker for unnecessary antibiotic prescribing in urinary tract infection (UTI) treatment. The study analyzed 249 asymptomatic patients receiving antibiotics, identifying 222 cases with ASPN and 133 with ASB (≥105 CFU/mL). Findings indicated that ASPN identified 40% more instances of unnecessary antibiotic use compared to ASB, suggesting that it may be a better tool for detecting inappropriate antibiotic prescribing.
Whitney Hartlage, PharmD, an antimicrobial stewardship and infectious diseases clinical pharmacist at UW Medicine, explained that her team's collaboration with colleagues at critical access hospitals highlighted the need to address the overdiagnosis and overtreatment of UTIs. Hartlage explained that the traditional ASB definition, which is based on urine culture results showing >100,000 CFU/mL of bacteria without UTI symptoms, has limitations. She emphasized that this definition often excludes patients who do not exhibit significant bacteriuria or have low colony count growth or mixed flora in their urine, meaning they may still be treated with antibiotics despite not meeting the traditional ASB criteria.
What You Need To Know
ASPN identified 40% more cases of unnecessary antibiotic use compared to the traditional ASB definition, offering a more comprehensive marker for inappropriate prescribing.
Clinicians’ overreliance on urinalysis results has led to unnecessary antibiotic treatments, despite the test's low predictive value for diagnosing UTIs.
Antimicrobial stewardship programs could improve by incorporating ASPN to reduce unnecessary urinalysis and enhance clinician education on proper interpretation of results.
“ASPN provides a more inclusive measure for unnecessary antibiotic prescribing,” said Hartlage. By including patients with asymptomatic pyuria and/or nitrituria (ASPN), the study captured more instances of inappropriate antibiotic use than the traditional ASB definition, offering a more effective approach for antimicrobial stewardship programs to tackle unnecessary antibiotic treatment.
The study also pointed out the challenges clinicians face when interpreting urinalysis results. Hartlage noted that many clinicians rely too heavily on urinalysis results to diagnose UTIs, despite the test's low positive predictive value for UTI diagnosis. This overreliance on urinalysis alone, often without correlating with symptoms, contributes to the unnecessary initiation of antibiotics. According to Hartlage, addressing this issue should be a priority for antimicrobial stewardship programs.
To improve stewardship efforts, Hartlage suggested that incorporating patients with asymptomatic pyuria (ASPN) in addition to those with ASB could offer a more comprehensive understanding of inappropriate antibiotic use for UTIs. "This approach could inform interventions aimed at reducing unnecessary urinalysis collection and educating clinicians on proper urinalysis interpretation," she concluded. These findings underline the importance of revisiting current definitions and measures to enhance antimicrobial stewardship and combat the overuse of antibiotics in UTI treatment.
Reference
Hartlage W, Castillo AY, Kassamali Escobar Z, et al. Stewarding the inappropriate diagnosis and treatment of urinary tract infection: leveraging the urinalysis to understand true antibiotic overuse. Antimicrob Steward Healthc Epidemiol. 2025;5(1):e49. Published 2025 Feb 17. doi:10.1017/ash.2025.26
