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Increasing colony-count threshold may reduce antimicrobial use for asymptomatic bacteriuria, candiduria
An intervention in which the colony-count threshold was increased for identifying potential urinary pathogens among hospitalized patients reduced antimicrobial prescribing for the treatment of asymptomatic bacteriuria and candiduria, according to a research letter published in JAMA Internal Medicine.
“Treatment of asymptomatic bacteriuria and candiduria remains a leading reason for unnecessary antimicrobial use among hospitalized patients, yet the optimal colony-count threshold for identifying and reporting growth from inpatient urine cultures is unknown,” Marc-Andre Smith, MD, MSc, of the Centre for Quality Improvement and Patient Safety and the University of Toronto and the department of microbiology at Sunnybrook Health Sciences Centre in Toronto, and colleagues wrote.
Researchers increased the threshold for identifying potential uropathogens from urinary cultures submitted from inpatient units from 104 CFU (colony-forming units)/mL or greater to 105 CFU/mL in March 2017.
They conducted a controlled interrupted time series study, which included an intervention group (all patients with low-colony-count urine culture) and a control group (consisting of every second patient with a high-colony count, defined as 105 CFU/mL).
Preintervention period was March 2016 to February 2017 and postintervention was March 2017 to February 2018.
The primary outcome of the study was the rate of monthly treatment of asymptomatic bacteriuria and candiduria. Secondary outcomes included days of antimicrobial therapy, the proportion of patients with untreated UTIs and hospital readmission, death or transfer to critical care within 14 days.
Within the 2 years, 30% of patients had a low colony count and 70% of patients had a high colony count.
Researchers found that the intervention was associated with a reduction in antimicrobial prescribing for asymptomatic bacteriuria and candiduria among the low colony-count group when compared with the high colony-count group (incidence rate ratio = 0.14; 95% CI, 0.03-0.64).
In addition, researchers noted that, when clinicians requested low-colony-count urine cultures to be worked up, patients were more likely to have a UTI than asymptomatic bacteriuria and candiduria (35% vs. 7%).
In addition, based on studies that suggest 20% of hospitalized patients receiving antibiotic therapy experience an adverse drug event, researchers estimated that raising the threshold averted fourteen adverse drug events annually.
“The simple change of raising the threshold for identifying potential urinary pathogens may avert nearly a third of asymptomatic bacteriuria and candiduria treatment among hospitalized patients and could have scalable impact on improving antimicrobial use in acute care hospitals,” the researchers wrote. – by Melissa J. Webb
Disclosures: The authors report no relevant financial disclosures.