Emma was a 5-year-old girl who previously enjoyed good health. She had been having fever for 4 days without localising symptoms. She had received oral paracetamol and ibuprofen from a pharmacy, but her fever persisted. She was increasingly lethargic with poor appetite and was admitted via the emergency department. On arrival, Emma appeared tired with poor perfusion and a capillary refill time of 3 seconds. Her blood pressure was 74/34 mmHg, and she was tachycardic at 150 beats per minute. Systemic examination was otherwise unremarkable. Initial blood tests showed sodium 145 mmol/L, potassium 4.9 mmol/L, urea 12 mmol/L (RI: 1.8–6.4 mmol/L), creatinine 120 µmol/L (RI: 33–59 µmol/L) and lactate 3.0 mmol/L (RI: 0.5–2.2 mmol/L). Her venous blood gas showed metabolic acidosis with pH 7.24, pCO2 3.1 kPa (RI: 4.7–6.0 kPa), bicarbonate 9.5 mmol/L (RI: 22–26 mmol/L) and base excess −15.9 mmol/L (RI: -2–2.0 mmol/L). Her urine dipstick was positive for leukocytes and nitrite. What would be your clinical approach in this case?