2026 Southeastern Residency Conference

Authors: Jada R. Guilford, PharmD; Taylor J. Merritt, PharmD; Sarah B. Green, PharmD, BCIDP, AAHIVP; Sujit Suchindran, MD, MPH; Benjamin Albrecht, PharmD, BCIDP; Emory University Hospital, Atlanta, GA  

Background: For more than 60 years, Vancomycin has been used to treat a variety of infections due to gram-positive organisms. Vancomycin has the potential to be nephrotoxic and ototoxic, subjecting patients to possible adverse events, and requires frequent monitoring to ensure appropriate use, increasing healthcare costs. Clinical guidelines currently recommend utilizing the ratio of 24-hour area under the curve (AUC) to minimum inhibitory concentration (MIC) for as the therapeutic target for dosing and monitoring, as this method improved patient outcomes in methicillin-resistant Staphylococcus aureus (MRSA) infections by ensuring adequate drug exposure while minimizing side effects. Currently, target AUCs range from 400-600 mg*hour/L for MRSA infections, assuming an MIC of ≤1 mg/L; however, there is limited data to support an AUC-based dosing strategy for non-MRSA gram-positive bloodstream infections. The purpose of this study is to assess the differences in select patient outcomes, particularly mortality and adverse events, by comparing time to blood culture clearance in patients with a vancomycin AUC ≥ 400 mg*hour/L and those with AUC <400 mg*hour/L within 5 days of therapy for non-Staphylococcus aureus and non-Staphylococcus lugdunensis gram-positive bloodstream infections.
Methods: This is an Institutional Review Board (IRB)-approved, single center, retrospective observational study. Patients were included if they were 18 years or older with a blood culture positive for a non-Staphylococcus aureus or non-Staphylococcus lugdunensis gram-positive organism and received IV vancomycin between May 1, 2024 and April 22, 2025. Patients were also included if they received ≥120 hours of vancomycin, had at least 1 vancomycin level, and vancomycin was still included in the antimicrobial regimen within 48 hours of culture clearance. Patients were excluded if the vancomycin indication was CNS infection, osteomyelitis, or endocarditis or if they did not meet the criteria for use of the Emory Healthcare AUC dosing protocol: on hemodialysis, peritoneal dialysis, or CRRT, had an acute kidney injury (AKI), weight >250 kg or BMI <20 kg/m2, or a peri-operative indication.
Results: A total of 55 patients met inclusion criteria, including 32 patients with an AUC <400 mg*hour/L and 23 patients with an AUC ≥400 mg*hour/L. There was no difference in the primary outcome of time to blood culture clearance between groups. The average time to blood culture clearance was 34.7 hours for AUC <400 and 37.1 hours for AUC ≥400 (p=0.515). More patients in the AUC ≥400 mg*hour/L group experienced acute kidney injury, but this difference was not statistically significant (17.4% vs 3.1%, respectively). Toxicity is typically seen in AUC > 650 mg*hour/L, and median AUC for each group was 293 mg*hour/L and 519 mg*hour/L respectively. There were no incidences of ototoxicity and one case of inpatient mortality in both groups. Inpatient length of stay was a median of 11 days (IQR 7-21.5) for AUC <400 mg*hour/L and 27 days (IQR 9-43.5) for AUC ≥400 mg*hour/L.
Conclusions: Both AUC groups had similar times to blood culture clearance without significant rates of adverse events or all-cause mortality.  Lower AUCs were associated with decreased length of stay; however, due to low rates of adverse events, and no matching for acuity beyond exclusion, this difference may not be related directly to different AUCs.