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UTI Management: It’s All in the Culture

      A new study covering almost all nursing home residents in Ontario, Canada, has shown highly variable urine culturing rates across facilities and a strong association of culturing with antibiotic use and Clostridioides difficile infection — a diagnostic “cascade effect,” the authors reported.
      Nursing home urine culturing explained 40% of the variation in antibiotic use across facilities, and was an even stronger predictor of antibiotics primarily used to treat urinary tract infections (UTIs).
      “Residing in a high-urine-culturing facility results in an increased likelihood of receiving a urine culture, an increased likelihood of receiving an antibiotic, and ultimately, an increased likelihood of C. difficile infection,” said Kevin Antoine Brown, PhD, of Public Health Ontario, the University of Toronto, and the Institute for Clinical Evaluative Sciences, and his coinvestigators in an article in Clinical Infectious Diseases [Jun. 14, 2019; doi: 10.1093/cid/ciz482].
      Nicole Brandt, PharmD, MBA, BCGP, BCPP, FASCP, professor of pharmacy practice and science at the University of Maryland School of Pharmacy, told Caring for the Ages that the study strengthens the evidence that “facility-level factors — not resident-level factors — influence prescribing [of antibiotics], and that there’s a cascade that happens from doing a urine culture.”
      The Canadian study, which was based on quarterly assessments conducted between April 2014 and January 2017 in 591 nursing homes (covering more than 90% of nursing home residents in Ontario), used the trove of linkable medical and administrative data collected through administration of Ontario’s system of publicly funded health care.
      Urine culturing, measured as the proportion of residents with a urine culture in the prior 14 days, varied from 3.4% in the lowest 10th percentile to 14.3% in the 90th percentile. It was found to be a strong predictor of antibiotic use, both before and after adjustment for 14 resident characteristics considered to be risk factors for either antibiotic receipt or C. difficile infections (such as days of prior hospital stays and variables relating to functional status, incontinence, and devices used).
      At the facility level, each doubling in culturing was associated (after adjustment) with a 1.21-fold increase in total antibiotic use — and a 1.33-fold increase in urinary antibiotic use — in the 30 days after assessment. The incidence of C. difficile infection occurring during the 90 days after assessment increased 1.18-fold with each doubling of urine culturing.The AMDA guidelines list five signs and symptoms — dysuria, urinary frequency, urinary urgency, suprapubic pain, and gross hematuria — as likely indicators of uncomplicated cystitis in nursing home residents. The associated diagnostic algorithm can be used to promote antibiotic stewardship in various PALTC populations.
      Also noteworthy, the authors reported, was the secondary observation that facilities with low urine-culturing rates had a slightly lower 30-day mortality than facilities with high urine-culturing rates. This demonstrated, they said, “that there were no gross harms related to less frequent urine culturing.”
      The prevalence of asymptomatic bacteriuria in long-term care and the appropriateness of urine culturing in this setting has become a focus of antibiotic stewardship initiatives in recent years. Skilled nursing facilities now have a selection of guidelines and criteria available for the appropriate use of urine cultures and the diagnosis of UTIs.
      Most recently, AMDA — The Society for Post-Acute and Long-Term Care Medicine has issued consensus recommendations for the diagnosis and empirical therapy of uncomplicated cystitis in noncatheterized nursing home residents. The guidelines are part of the Improving Outcomes of UTI Management in Long-Term Care (IOU) Project (https://paltc.org/content/iou-toolkit).
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      Algorithm for the diagnostic approach to uncomplicated cystitis in noncatheterized nursing home residents (from Nace et al., J Am Med Dir Assoc 2018;19:765–769)
      Identifying and integrating approaches for the diagnosis of patients with cognitive impairment and altered mental status is an important part of antimicrobial stewardship with respect to urine cultures and UTIs. “The altered mental status is one of the biggest drivers for getting a urinalysis and ordering a urine culture,” Dr. Brandt said.
      Dr. Brandt and her colleagues at the center have developed a series of educational webinars on antimicrobial stewardship that are publicly accessible to medical providers and consultant pharmacists (“Antimicrobial Stewardship Educational Activities,” http://bit.ly/31S0koP). One of these webinars covers UTI diagnosis and the role of diagnostic stewardship in long-term care. Others address the incorporation of antibiogram data and how to measure its effectiveness.
      The Centers for Disease Control and Prevention’s National Healthcare Safety Network offers long-term care facilities a customized UTI surveillance module (https://www.cdc.gov/nhsn/ltc/uti/index.html) that allows them to track both urine cultures and antibiotic starts for clinically suspected UTIs. The collected data can be used to assist with quality assurance and performance improvement initiatives and to inform prevention efforts.
      Antibiotic use in nursing homes has been studied for years by the Institute for Clinical Evaluative Sciences. In a study published in 2015, researchers looked at the variability of antibiotic use across nursing homes; they found that residents of high-use facilities are exposed to more antibiotic-related adverse outcomes than those living in low-use facilities — even if these residents have not directly received the drugs (JAMA Intern Med 2015;175:1331–1339).
      Christine Kilgore is a freelance writer in Falls Church, VA.