A 55-year-old man presents with worsening swelling of his left leg for three days. He has a high fever and is mildly confused. His wife states that his appetite has been poor since the onset of symptoms. This is his fifth such episode in two years. None of the previous events were this severe, with all rapidly responding to antibiotic therapy. His medical history is significant for poorly controlled type 2 diabetes mellitus for 10 years complicated by grade 3 diabetic retinopathy and stage 2 diabetic nephropathy.