500. Prevalence of Extended-Spectrum β-lactamase and Carbapenem-Resistant Gram-Negative Bacteria in Patients with Urinary Tract Infection and Urosepsis Admitted through Emergency Departments in the United States

BACKGROUND: Gram-negative infections due to extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, and carbapenem-resistant Enterobacteriaceae (CRE) and non-fermenting (CR-NF) strains, are increasingly encountered. Study objectives were to determine prevalence and associated risk factors and outcomes for these strains among emergency department patients hospitalized for urinary tract infection (UTI) at 11 US hospitals. METHODS: This was a prospective observational study of patients ≥18 years hospitalized for UTI. Clinical data were collected at the index visit. Urine was obtained for culture and susceptibility testing. Electronic medical record and telephone follow-up were conducted after 30 days for site laboratory results, treatment, and clinical outcomes. Positive culture was defined as 1 uropathogen with growth at ≥10(4) cfu/mL, or 2 with 1 or both at ≥10(5) cfu/mL, or ≥3 with 1 or 2 at ≥10(5) cfu/mL. Isolates with ceftriaxone (CRO) or meropenem MIC >1 μg/mL will undergo reference laboratory (IHMA, Inc., Schaumburg, IL) susceptibility testing, including against newer antibiotics and cefiderocol. RESULTS: We enrolled 774 participants between 2018 and 2019; 289 (37.3%) excluded due to urine culture not done, no growth, or contamination. Of 485 culture-positive participants (median age 56 years, 62.0% female), 432 (89.1%) grew 1 uropathogen, 48 (9.9%) 2, and 5 (1.0%) ≥3. Prevalences of CRO-resistant Enterobacteriaceae, CRE, and CR-NF were 19.9%, 2.1%, and 10.7%, respectively. At sites, 95.7% of CRO-resistant Enterobacteriaceae isolates were ESBL. Among participants with any or no antibiotic resistance risk factors, i.e., antibiotics, hospitalization, long-term care, or travel within 90 days, prevalence of CRO-resistant Enterobacteriaceae was 68/228 (29.8%) and 10/155 (6.5%), respectively. Among those with CRO-resistant vs. susceptible Enterobacteriaceae infections, ICU admission and death occurred in 9.9% vs. 6.6% and 3.7% vs. 1.0%, with median time home over 30 days, 24 vs. 27 days, respectively. CONCLUSION: Among US hospitalized patients with UTI, infections due to CRE remain uncommon; however, ESBL and CR-NF now account for a substantial proportion of cases and are associated with resistance risk factors and worse outcomes. DISCLOSURES: All authors: No reported disclosures.