Mrs. Randazzo is an elderly woman admitted to the hospital from a nursing home with a diagnosis of sepsis secondary to a urinary tract infection (UTI). She has been receiving piperacillin (Pipracil) for 24 hours and her temperature chart is showing a downward trend. The lab calls you with the initial results of the blood culture and states that gram-negative rods grew in two of three culture tubes. Do you need to call the attending physician for a change in antibiotic? Why or why not?.