A 7-year-old girl is admitted with fatigue, pallor, and decreased urine output following a 4-day history of bloody diarrhea. Laboratory findings reveal hemolytic anemia, thrombocytopenia, and elevated creatinine. A stool culture is positive for Shiga toxin-producing E. coli (STEC). The attending physician is discussing management strategies. Which of the following is the most appropriate initial treatment approach?
