Since the author has not replied, here is my guess: anti-venom somehow got transposed from one of the causes of serum sickness to the treatment. Seems unlikely, but I can’t figure out anything else. Here is how I’ve modified my notes:
Serum sickness and Serum sickness–like reaction result in arthritis, nephritis and a rash. Seen with cefaclor and minocycline. Treat with antihistamines, NSAIDS; steroids if necessary to continue using the offending agent (e.g. snake anti-venom).