1424. Examining the Relationship Between Vancomycin Area Under the Concentration–Time Curve and Serum Trough Levels in Adults with Presumed or Documented Staphylococcal Infections

Recent studies evaluating area under the concentration–time curve (AUC)-guided vancomycin dosing have reported reduced drug exposure and nephrotoxicity as compared with traditional trough-guided (target 15–20 mg/L) dosing for invasive infections, but studies exploring the relationship between vancomycin trough concentration and AUC remain limited. This was a retrospective observational study performed at two hospitals within a large health system. Patients receiving AUC-guided vancomycin dosing for a presumed or confirmed invasive staphylococcal infection between December 1, 2016 and July 31, 2017 were evaluated. Two steady-state serum vancomycin levels were obtained in each patient and used to determine the 24-hour AUC/MIC ratio; the AUC/MIC target was >600 mg/L hour for endocarditis and >400 mg/L hour for all other sources. The relationship between trough and AUC was explored using the Pearson product-moment correlation coefficient. Patient demographics and dosing details were also collected. Thirty-four patients were included in the study, with two patients having vancomycin levels drawn twice (36 sets of levels). Most patients were located in an ICU (91.2%) and 85.3% of patients had bacteremia, pneumonia or endocarditis. An organism was recovered from 28 patients (82.3%) of which 21 (75%) had a vancomycin MIC of 1 mg/L and 25 were S. aureus (89.3%). The mean vancomycin trough was 16.6 ± 6.1 mg/L and the mean AUC/MIC was 588 ± 156 mg/L hour. There was a strong correlation between vancomycin trough and 24-hour AUC (R2 = 0.731; P < 0.001; Figure 1). The rate of 24-hour vancomycin AUC/MIC target attainment was 91.2% (n = 31/34). Among patients with a trough >9 mg/L, 100% (n = 33) achieved AUC/MIC values >400 mg/L hour and 94% were >500 mg/L hour. Targeting a vancomycin trough between 15 and 20 mg/L frequently results in an AUC/MIC in excess of the target identified for efficacy. Considering the strong correlation observed between trough and AUC alongside practical challenges associated with wide-scale implementation of AUC monitoring, a reduced target trough in conjunction with targeted application of AUC-guided dosing warrants further evaluation. Relationship between 24-hour vancomycin AUC and serum trough. All authors: No reported disclosures.