PLE-3261

A previously healthy 57-year-old man comes to the physician because of a nonpruritic rash over both legs for 1 week and a low-grade fever for 2 days. He recently returned from a 2-week canoe trip on a river in Minnesota. His temperature is 37.2 C (99 F). Examination shows a 4 x 6-cm, macular, dark pink, ovoid lesion on the right posterior hip with central clearing and a punctate eschar near the center. There are macular ring lesions with central clearing over the medial tibia and anterior thighs of the lower extremities. He has no lymphadenopathy. What is the most likely causal organism?