192. The Use of Area Under the Curve to Determine Therapeutic Vancomycin Dosing in Skin and Soft Tissue Infections

Abstract Background The vancomycin AUC/MIC target ratio of 400 to 600 mg*h/L that is recommended (level IA+) in the 2020 IDSA/ASHP vancomycin TDM guidelines is appropriate for patients with complicated MRSA infections; using lower targets for less complicated infections may reduce the risk for nephrotoxicity without compromising efficacy. The current methodology surrounding vancomycin AUC/MIC targets is unrefined, with no source specific targets identified, especially for relatively lower risk MRSA infections such as skin and soft tissue infections (SSTIs). Methods This was a retrospective observational study of hospitalized patients at the Veterans Affairs Health Care System in San Diego, CA with a SSTI and prescribed intravenous vancomycin between January 1, 2016 and December 31, 2019. Patients included were adults, 18 years of age and older, treated with IV vancomycin with ≥1 measured concentration for at least one of the ICD-10 CM codes for SSTI. Patients were excluded if they had any of the following SSTIs: (1) osteomyelitis; (2) infection related to chronic ulcers or wounds; (3) head SSTI; (4) peri-rectal SSTI; (5) human or animal bite SSTI; (6) SSTI related to retained foreign body; (7) necrotizing SSTI; (8) surgical site infection. Patients were also excluded if they were undergoing dialysis or had severe immunosuppression. Results A total of 722 patients on vancomycin for a SSTI were identified from the database query for screening, and 243 (34%) met inclusion criteria for the study. Classification and Regression Tree (CART) modeling identified a calculated AUC of >253 as having the highest correlation with clinical success. Clinical cure was significantly different between the AUC ≤253 (6/9 [67%]) and AUC >253 (214/234 [91%]) cohorts (p=0.043). There were no differences in hospital length of stay or duration of vancomycin therapy. Nephrotoxicity occurred in seven patients, all of who had AUC >253. Conclusion Overall treatment success in patients with SSTIs was associated with a vancomycin AUC >253, which is lower than the guideline recommended range of 400–600. Identification of vancomycin AUC targets for other low risk sources of infection, such as UTIs, is needed to prevent vancomycin overexposure. Disclosures All Authors: No reported disclosures