A 28-year-old male farmer presented on October 30 with high fever, headache, low back pain, vomiting, and diarrhea, with continuous fever for 4 days and one episode of epistaxis. After taking paracetamol, the fever subsided but dizziness, oliguria, and painful urination developed. Lab results: WBC count 18×10<sup>9</sup>/L (neutrophils 60%, abnormal monocytes 12%, lymphocytes 23%), platelets 50×10<sup>9</sup>/L, and membranous material in urine. Despite treatment, urine output remains ~100ml/24h. Which treatment should be initiated?