By Richard R. Watkins, MD, MS, FACP, FIDSA, FISAC
Synopsis: A cohort study found that in patients receiving antibiotics for a urinary tract infection, a urinalysis with pyuria and/or nitrituria identified 40% more cases of unnecessary antibiotic use compared to asymptomatic bacteriuria.
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(1):e49.
The overprescribing of antibiotics for asymptomatic bacteriuria (ASB) has important negative consequences for patients, public health, and the healthcare system. These include adverse drug events, increased healthcare costs, and facilitating the spread of antimicrobial resistance (AMR). With a few exceptions (e.g., pregnancy, after kidney transplantation, and before a urologic procedure), treating ASB is contraindicated in routine clinical practice. One of the areas of confusion for many providers who treat urinary tract infections (UTIs) is the overreliance on urinalysis (UA) results. Indeed, patients with ASB often have an abnormal UA, such as pyuria or nitrituria, without clinical signs of infection like fever, dysuria, suprapubic tenderness, and urinary urgency and frequency. Therefore, Hartlage and colleagues sought to characterize the differences in patients inappropriately prescribed antibiotics with ASB compared to those with asymptomatic pyuria/nitrituria (ASPN).
The study was a retrospective cohort investigation that included 10 critical access hospitals. Patients were included who were at least 18 years of age and had urine testing performed (a urine culture plus a UA or a urine culture alone) during an outpatient, emergency department, or inpatient encounter. Patients were excluded if they had two or more criteria for systemic inflammatory response syndrome (SIRS), received antibiotics for a concurrent infection, had a UA without a culture, or had a legitimate indication for treatment of ASB. Asymptomatic was defined as having urine testing performed without signs or symptoms of a UTI. ASPN was defined as having positive leukocyte esterase, > 10 white blood cells (WBCs), or positive nitrites on a UA without signs or symptoms of a UTI. ASB was defined as a urine culture that grew > 105 colony-forming units (CFU)/mL of one or more species of bacteria without any evidence of UTI, regardless of UA results. The primary outcome was the prevalence of inappropriate antibiotic prescribing in asymptomatic patients with ASB and ASPN.
There were 824 patients included in the analysis. The median age of treated and non-treated patients was 74.6 years. Most of those treated for UTI or with ASPN or ASB were female (range, 65% to 85%). Of the 824 patients, 347 (42%) did not have clinical evidence of a UTI, 282 (34%) had ASPN, and 153 (19%) had ASB. Among the 347 without signs/symptoms of a UTI, 249 (72%) received an antibiotic. Of these, 222 (89%) had ASPN, 133 (53%) had ASB, and 123 (49%) had both. Having ASPN resulted in 99 additional cases of unnecessary antibiotic use.
Patients with a chronic urinary catheter had a greater chance of receiving antibiotics for asymptomatic UTI (11%) vs. no treatment (4%). Those with altered mental status alone had a higher risk for being treated for UTI than not treated (14% vs. 10%, respectively). Finally, a urine culture with any quantity of growth led to treatment in 210 (84%) of those who were asymptomatic for a UTI.
Commentary
To make an accurate diagnosis of a UTI, a patient needs both clinical signs and symptoms along with laboratory evidence. Despite advances in molecular assays, the most common laboratory testing in ambulatory, emergency department, and inpatient settings remains a UA and culture. Thus, it is paramount that clinicians be able to understand the results of UAs and urine cultures to avoid unnecessary antibiotic prescribing. Therefore, the study by Hartlage and colleagues is interesting and important from an antibiotic stewardship perspective. They found a high rate of antibiotic prescribing in patients with ASPN, even more so than with ASB. Even though the difference between ASB and ASPN has little clinical significance, it is important from a surveillance standpoint. Antibiotic stewardship programs might increase their impact by tracking inappropriate antibiotic prescribing for UTIs using ASPN rather than urine culture results.
The study had a few limitations. The results may have been affected by unknown confounding variables as a result of the retrospective cohort design. Because the study was conducted at critical access hospitals with resource constraints and slower turnaround times for urine cultures, the results might not be generalizable to urban and suburban medical facilities. Finally, the data obtained were dependent on accurate documentation of UTI signs and symptoms by the evaluating provider.
Clinicians need to be better informed about the management of UTIs, including how to interpret UAs and knowing when antibiotics are not necessary. This important task should be performed by antibiotic stewardship program personnel and infectious disease physicians. Future guidelines on UTIs should discuss the role of ASPN along with ASB.
Richard R. Watkins, MD, MS, FACP, FIDSA, FISAC, is Professor of Medicine, Division of Infectious Diseases, Northeast Ohio Medical University, Rootstown, OH.
A cohort study found that in patients receiving antibiotics for a urinary tract infection, a urinalysis with pyuria and/or nitrituria identified 40% more cases of unnecessary antibiotic use compared to asymptomatic bacteriuria.
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