There is limited evidence about optimal anticoagulant dosing for venous thromboembolism (VTE) prophylaxis in underweight patients. The purpose of this study was to characterize dosing strategies used in underweight patients and compare the incidence of bleeding and VTE to patients receiving a standard dose. This multi-center retrospective study evaluated medicine patients who weighed 45 kilograms or less and received VTE prophylaxis with unfractionated heparin or enoxaparin. We categorized subjects into groups as either standard or reduced dose and compared the incidence of bleeding and VTE between groups. Of the 300 patients included in the outcome analysis, 40.7% received a reduced dose regimen, most often enoxaparin 30 mg daily. Standard dose was associated with major bleeding compared with reduced dose, when adjusted for age, gender and admission hemoglobin (odds ratio 4.73, 95% confidence interval 1.05 to 21.34). Incidence of clinically relevant non-major bleeding (2.4% vs. 1.1%) and VTE (0.6% vs. 0%) were similar between groups. Anticoagulant dose reduction for VTE prophylaxis in underweight hospitalized medicine patients is common practice and associated with less major bleeding.

Background Hematologic malignancy patients have high rates of antibiotic exposure, and increasing resistance is a major concern, particularly with extended-spectrum beta lactamases (ESBL) in Enterobacterales blood stream infections (BSIs). Identifying risk factors for ESBL-producing Enterobacterales (ESBL-E) BSIs may facilitate faster appropriate antibiotic use and decrease mortality. Methods This was a retrospective study of patients with hematologic malignancies and Escherichia coli or Klebsiella spp. bacteremia admitted to Carolinas Medical Center in Charlotte, NC from January 2010 through September 2020. The primary objective was to compare 30-day mortality rates for patients with ESBL-E BSIs to those with non-ESBL-E BSIs. Fisher’s exact or Mann-Whitney U tests were used for primary and secondary clinical outcomes as appropriate. Risk factors associated with 30-day mortality and ESBL production were assessed as secondary objectives using logistic regression models. Results A total of 28 patients with ESBL-E BSIs and 60 patients with non-ESBL-E BSIs were included. The 30-day mortality rate with ESBL-E BSIs was 25% compared to 15% with non-ESBL-E BSIs (P = .373). In-hospital mortality, 30-day infection recurrence, intensive care unit (ICU) admission, and length of stay after culture were not significantly different. However, time to optimal therapy was longer in the ESBL-E group (median 42.3 vs 1.9 hr; P < .001). Multivariate logistic regression analysis showed an association of 30-day mortality with ICU admission (OR 16.7; 95% CI, 3.56-78.4; P < .001) and longer time to optimal therapy (OR 1.03; 95% CI, 1.0-1.05; P = .026). Prior ESBL-positive culture was associated with ESBL-E BSI in the univariate logistic regression (OR 9.83; 95% CI, 1.05-92.56; P = .046). Additionally, prolonged neutropenia (OR 3.05; 95% CI, 1.01-9.23; P = .049) and prior intravenous antibiotic use (OR 2.96; 95% CI, 0.96-9.09; P = .059) were associated with ESBL-E BSI in the multivariate analysis. Conclusion Significantly longer time to optimal therapy was seen in ESBL-E BSIs and was associated with mortality in patients with hematologic malignancies. The identified ESBL risk factors create an opportunity to decrease delay in optimal therapy through risk stratification during initial antibiotic selection. Disclosures Ekaterina Kachur, PharmD, BCOP, Bristol Myers Squibb (Advisor or Review Panel member)Genentech (Employee)Glaxosmithkline (Advisor or Review Panel member)Kyowa Kirin (Advisor or Review Panel member)

Background Cidofovir (CDV) dosing is based on limited clinical evidence and varies by indication. The optimal dose to achieve a virologic response has not been established. Routine lab monitoring, renal dose adjustments, and co-administration with intravenous (IV) fluids and probenecid are recommended to limit CDV-associated nephrotoxicity but lack a standard approach. Methods This was a retrospective evaluation of patients admitted to Atrium Health’s Carolinas Medical Center or Levine Children’s Hospital who received at least one dose of CDV from August 1, 2014 through June 30, 2021. The primary objective was to describe CDV prescribing patterns. Secondary objectives included evaluating virologic response, nephrotoxicity, and IV fluid and probenecid use. Results A total of 38 adult and 26 pediatric patients were included and received 44 and 60 CDV doses, respectively. Adult dosing was variable, but the most common regimens for BK virus infections included CDV 0.5 mg/kg every other week for solid organ transplant recipients (Figure 1A-B) and 1 mg/kg weekly for stem cell transplant recipients (Figure 1C). Dosing for adenovirus infections was inconsistent (Figure 1D). All but one of the adult patients evaluated had a decrease in viral load during the first two weeks (Figure 2A-D). In pediatric patients, the most common CDV dose was 1 mg/kg three times weekly which was used in 67% of patients across all indications (Figure 1E-I). Three evaluated pediatric patients had an increase in viral load (Figure 2E-H), but no similarities in dosing or indication were noted. The rate of nephrotoxicity based on pre-defined increases in serum creatinine was 29% for adults and 14% for pediatric patients. Use of IV fluid boluses and probenecid was inconsistent in both adult and pediatric patients (Table 1). Of the patients that did not receive probenecid, only 16.7% of adults and no pediatric patients received a CDV dose > 1 mg/kg. Conclusion Evaluation of virologic response to CDV was limited by small sample size. However, high variability in prescribing patterns highlights the need for standardized, indication-specific dosing. Standardization of IV fluid and probenecid use along with guidance on CDV dose adjustments in patients with renal insufficiency may help decrease the risk of CDV-associated nephrotoxicity. Disclosures All Authors: No reported disclosures.