A 40-year-old male returned from a deer-hunting trip approximately 6 weeks
ago, and presents to clinic with multiple complaints. He states that recently he
has had worsening joint pain and “arthritis” in multiple joints that seems to move
to different spots. Patient also complains of some numbness in his feet bilater-
ally. The patient denies any medical problems and he had a normal annual phys-
ical prior to hunting trip. On further questioning, he remembered having a rash
on his body and the lesions were circular and appeared to be resolving in the
center. He noted that he felt really bad once he got home with muscle ache
(myalgias), joint ache (arthralgias), stiff neck, and severe headache. He also
remembered that many of his hunting friends had experienced flea and tick bites
and is quite sure he was bitten as well. The physical exam is essentially normal
except some joint tenderness of left knee and right shoulder. After making your
diagnosis you gave him a prescription for erythromycin.
What is the most likely diagnosis?
What is the biochemical mechanism of action of erythromycin?