Background Current IDSA guidelines for the treatment of UTIs discourage oral β-lactams based on lack of adequately powered studies to assess efficacy compared to fluoroquinolones or TMP-SMX. However, increasing E. coli and Klebsiella spp. resistance to first-line antibiotics has necessitated the need for alternative agents. Methods This was a single-center retrospective chart review of adult patients discharged from the University of New Mexico ED with twice-daily cephalexin for the treatment of uncomplicated UTIs from January 1, 2019 to December 31, 2019. Patients were excluded if < 18 years of age, received ≥ 10 days of cephalexin, received antibiotics for other indications, received antibiotics within 60 days prior to ED visit, or had structural abnormalities. The primary outcome of this study was the proportion of patients with clinical success 30 days after discharge from the ED. Patients not meeting criteria for clinical failure were classified as clinical success. Clinical failure was defined as return of patient within 30 days due to non-resolving or worsening UTI symptoms or change in antibiotic therapy after discharge based on urine culture and susceptibilities. Results A total of 264 patients were included for evaluation. The average age was 56.0 ± 20.2 years and 82.6% were female. Patients received an average 5.6 ± 0.9 days of antibiotic therapy including IV therapy. Of the 264 patients included for evaluation, 81.1% met criteria for clinical success. Of the patients with clinical failure, 29 (13.6%) required a change in antibiotics based on cultures and sensitivities, 17 (6.4%) returned for non-resolving or worsening symptoms, and 4 (1.5%) required both a change in antibiotics and returned for non-resolving or worsening symptoms. Conclusion Short courses of twice-daily cephalexin appear to be safe and effective for empiric treatment of uncomplicated UTIs. Adding β -lactams back to the antibiotic armamentarium for UTI treatment may delay the development of resistance to non- β -lactam antibiotics, ensuring their future utility. Disclosures All Authors: No reported disclosures

Background Continuous infusion vancomycin (CIV) is an attractive alternative to intermittent infusion vancomycin (IIV) as it may result in more rapid attainment of target serum drug concentrations, provide ease of monitoring, and decreased risk of nephrotoxicity. At our institution CIV has been the preferred infusion method for over 20 years. The purpose of this study was to examine the time to therapeutic goal among patients receiving IIV compared to CIV for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. Secondary objectives included all-cause readmission, relapse, and mortality 30 days after completion of therapy. Methods This was a single-center, retrospective study of patients who received vancomycin for MRSA bacteremia between January 2018 and December 2021. Included patients were ≥ 18 years of age, had ≥ 1 blood culture positive for MRSA, received vancomycin for > 10 days, and had follow-up in the outpatient parenteral antimicrobial therapy clinic. Patients who were pregnant, received vancomycin for ≤ 10 days, or were diagnosed at an outside hospital were excluded. All patients were started on IIV then transitioned to CIV. Patients on IIV with an appropriately drawn trough between 15-20 mcg/mL were considered therapeutic. For patients on CIV, a single random level between 17-25 mcg/mL, corresponding to an AUC/MIC of 400-600 mcg·h/mL, was considered therapeutic. Results Sixty-three patients with 65 MRSA bacteremia episodes were included. Significantly fewer patients achieved a therapeutic goal on IIV compared to patients on CIV (52.3% vs. 83.1%, p-value < 0.01). Of the 31 patients who did not reach the IIV trough goal, 87.1% became therapeutic when switched to CIV. Patients on IIV took 3.6 days, on average, to reach the target goal, compared to 1.9 days when patients were switched to CIV (95% confidence interval 0.50 – 2.96, p-value < 0.01). No patients experienced relapse or mortality 30 days after completion of therapy. Six patients (9.2%) were readmitted 30 days after completion of therapy. Conclusion CIV enabled patients with MRSA bacteremia to achieve the AUC/MIC goal significantly faster than when receiving IIV. Patients who were unable to achieve a therapeutic goal on IIV became therapeutic once switched to CIV. Disclosures Martha Carvour, MD, PhD, The Suga Project/The Suga Project Foundation: I provide consultation and support but do not receive compensation.