Background: Ceftriaxone is a commonly used antibiotic for the treatment of susceptible Enterobacterales infections. There is currently limited clinical data on the optimal dose of ceftriaxone for Enterobacterales bacteremia. Objectives: To evaluate the rate of clinical failure of ceftriaxone 1 g versus 2 g daily in patients with Enterobacterales bacteremia. Methods: This was a retrospective cohort study of patients admitted to any of the 3 New York University Hospitals: Long Island, Tisch, or Brooklyn, with ceftriaxone-susceptible Enterobacterales bacteremia, receiving ceftriaxone 1 or 2 g daily from October 2019 to September 2020. The primary outcome was 90-day rate of clinical failure. Clinical failure was defined as escalation of therapy, relapse of infection, or all-cause mortality. Results: A total of 124 patients, 58% in the 1-g group and 42% in the 2-g group, were included. There was no statistically significant difference found in the primary outcome. The 90-day rate of clinical failure was 16.7% versus 9.6%, P = 0.260. There were no statistically significant secondary outcomes, although infection relapse rates at 90 days were numerically greater in the 1-g group (11.1% vs 1.9%, P = 0.078). Hypoalbuminemia was the only variable associated with an increased risk of clinical failure (odds ratio = 4.03; 95% confidence interval [CI] = 1.12-14.50, P = 0.033). Conclusion: In our exploratory findings, there was no statistically significant difference with the 90-day rate of clinical failure between ceftriaxone 1 g versus 2 g daily, although there was a numeric trend toward an increased rate of infection relapse within the 1-g group. Hypoalbuminemia was associated with an increased risk of clinical failure. Prospective studies are warranted to confirm these findings.

Background Penicillin allergies are reported in approximately 10% of patients in the US but ∼90% of these allergies can be de-labeled. Consequences of inappropriate allergy labeling leads to use of alternative agents associated with increased adverse events and resistance rates, leading to worse outcomes. Though all beta-lactam agents share the core beta-lactam ring, the R1 side chain has been identified as the focus of cross-reactivity. Agents that do not share the same or similar R1 side chain are likely to have negligible risk of hypersensitivity reactions. The purpose of this study was to assess the incidence of hypersensitivity reactions in patients with a documented beta-lactam allergy that received a beta-lactam agent with a different side chain based on recommendation by an antimicrobial stewardship clinical pharmacist. Methods This was a retrospective, single-center, observational study of patients admitted to NYU Langone Hospital – Long Island from October 2019 to February 2022. Data was collected by review of the electronic medical record and descriptive statistics were generated as appropriate. The primary outcome was the proportion of patients that experienced a hypersensitivity reaction to a beta-lactam agent with a different side chain. Secondary outcomes included impact of antimicrobial stewardship intervention by clinical pharmacists, avoidance of alternative antibiotics, and cost comparison between agents requested and recommended. Results A total of 181 patients were included in the final analysis, including 37 patients with a history of anaphylaxis. No patients with a documented beta-lactam allergy experienced a hypersensitivity reaction upon receiving a beta-lactam agent with a different side chain. Within the cost comparison, meropenem accounted for 45.6% and 75.9% of the total minimum and maximum wholesale costs of requested agents, respectively. Conclusion The results of this study suggest that receipt of a beta-lactam agent with a different side chain is safe in patients with a history of beta-lactam allergy, including anaphylaxis history, and supports 'in the moment' antimicrobial stewardship intervention to ensure patients receive optimal therapy when access to in-depth allergy history or detailed patient interview is not feasible. Disclosures All Authors: No reported disclosures.

Background Ceftriaxone-susceptible (CRO-S) and piperacillin-tazobactam-non susceptible (TZP-NS) Enterobacterales isolates have become a frequently isolated phenotype emerging in practice. The genotypic profile is still not clearly elucidated, although prior genotypic sequencing data of these isolates with this phenotypic profile suggests that they are not extended-spectrum beta-lactamase (ESBL) producers. Due to the unfamiliarity with this phenotype and the potential for overuse of broad-spectrum antibiotics, we investigated the clinical outcomes of CRO-S/TZP-NS isolates with carbapenem versus non-carbapenem beta-lactam (NCBL) therapy. Methods This was a retrospective chart review of patients with a diagnosed infection caused by a CRO-S/TZP-NS Enterobacterales isolate admitted to any of the three NYU hospitals: Long Island, Tisch, or Brooklyn campuses, treated with a beta-lactam (BL) antibiotic from October 2015 to October 2020. The primary outcome was treatment failure defined as an escalation of antibiotics due to clinical worsening, 30-day all-cause mortality, or relapse of infection with the same genus and species. Patients who received ≥ 72 consecutive hours of BL antibiotics were considered to be on definitive therapy. Results A total of 111 patients were included in this study, 9 in the carbapenem group and 102 in the NCBL group. There was no statistically significant difference in the clinical failure rate between the two groups (0% vs 10.8% respectively, P=0.56). A univariate analysis assessed the association of clinical failure with TZP, CRO, cefpodoxime, cefepime, and 1st-3rd generation cephalosporins grouped. There were no statistically significant increases in 30-day treatment failure in any of the individual categories. Conclusion There were no statistically significant differences in 30-day failure with the use of carbapenem vs NCBL antibiotics. No individual BLs or classes were associated with an increased risk of clinical failure. This study suggests that there is a role for NCBL antibiotics for Enterobacterales isolates with this phenotypic presentation and supports prior data that they are less likely to be ESBL producers. Prospective studies are warranted to confirm these findings. Disclosures All Authors: No reported disclosures