Study: 72% of Asymptomatic UTI Patients Receive Unnecessary Antibiotics

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A new study suggests that inappropriate antibiotic use for urinary tract infections (UTIs) may be more common than previously recognized, with many patients receiving treatment despite showing no symptoms.

Researchers from the University of Washington Center for Stewardship in Medicine found that nearly three-quarters of asymptomatic patients who underwent urine testing at participating hospitals were prescribed antibiotics, highlighting a significant opportunity for antimicrobial stewardship.

The study—published in Antimicrobial Stewardship & Healthcare Epidemiology—analyzed data from 10 critical access hospitals (CAHs) across the US, reviewing cases of 1036 adult patients who underwent urinalysis and urine cultures between September 2022 and May 2023. Of the 824 patients who met inclusion criteria, 347 (42%) showed no signs or symptoms of a UTI. Despite this, 249 of these asymptomatic patients (72%) were treated with antibiotics.

The study introduced a broader measure—referred to as asymptomatic pyuria and/or nitrituria (ASPN)—which includes patients with positive urinalysis results but no bacterial growth in their urine culture. The ASPN criteria captured 40% more cases of unnecessary antibiotic use compared to the traditional definition of asymptomatic bacteriuria (ASB), which relies on significant bacterial growth (≥100 000 colony- forming units [CFU]/ml) in the absence of symptoms.

Current clinical guidelines discourage antibiotic treatment for ASB except in select cases, such as pregnancy or prior to certain urological procedures. However, the study's findings suggest that reliance on ASB alone underestimates the true extent of inappropriate antibiotic prescribing. Many clinicians may initiate treatment based on urinalysis results alone, misinterpreting indicators like pyuria or nitrituria as definitive signs of infection. This tendency may be particularly pronounced in CAHs, where urine culture results can take several days to return, leading to empiric antibiotic prescribing.

The authors argue that expanding antimicrobial stewardship efforts to include ASPN cases—rather than focusing solely on ASB—could more accurately capture and curb unnecessary antibiotic use. By reviewing cases with abnormal urinalysis results, stewardship programs could identify and educate clinicians who prescribe antibiotics based on incomplete diagnostic information. Such efforts could also promote better diagnostic practices, reducing the frequency of unnecessary urinalysis testing that often leads to overdiagnosis and overtreatment.

The study has some limitations, including its retrospective design and reliance on clinician documentation. Additionally, findings may not fully apply to larger urban hospitals, where laboratory resources and diagnostic turnaround times differ. Nevertheless, the study underscores the need for more refined approaches to antibiotic stewardship in UTI management, particularly in resource-limited settings.

With antibiotic resistance on the rise, optimizing prescribing practices is a critical public health priority. The researchers suggest that incorporating a broader range of diagnostic markers into stewardship efforts could help reduce unnecessary antibiotic exposure, improving patient outcomes while slowing the development of resistant infections.

"Additional studies are needed to identify the prevalence of ASPN in other settings and measure the impact of stewardship program review and intervention," first author Whitney Hartlage, PharmD, an antimicrobial stewardship and infectious diseases clinical pharmacist at UW Medicine, and colleagues concluded.

Source: 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:e49. doi:10.1017/ash.2025.26