A 50-year-old woman presents to the emergency department with a three-day history of escalating fever, profound chills, constant dull pain in her right upper abdomen, generalized weakness, and progressively worsening yellow discoloration of her skin and eyes. She reports recent travel to an endemic area and mentions that her spouse had similar but self-resolving gastrointestinal symptoms a few weeks prior. On examination, she appears acutely ill and lethargic. Her skin and sclera are markedly jaundiced. Palpation of the abdomen reveals significant tenderness and guarding in the right upper quadrant. Her vital signs are: temperature 39.9°C (103.8°F), pulse rate 135/min, blood pressure 98/60 mm Hg, and respiratory rate 24/min. Capillary refill time is prolonged at 4 seconds. A CT scan of the abdomen reveals a large, well-defined, hypodense lesion with rim enhancement in the right hepatic lobe, consistent with an abscess. Considering her presentation and the imaging findings, what is the most likely diagnosis and the immediate appropriate initial management strategy for this patient?