Case Presentation: This patient is a 74-year old male with CAD, HFpEF, HTN, Type 2 DM, CKD3, and obesity admitted for sepsis secondary to bilateral lower extremity purulent cellulitis, complicated by acute decompensated heart failure. He was started on cefepime 2 g twice daily and on vancomycin (vanco), dosed daily by level. After receiving only two doses of vanco 1g, the patient was found to have persistently elevated [...]