Since we have seen evidence of medical treatments off camera (some shots with bandages on contestants, etc...) They could EASILY treat these infections on the island off camera. Contestants can sign a waiver, and stay in the game. I bet they already sign massive waivers.

Looking at Penner's knee infection (they only showed it after it had swollen up until he couldn't move it) it was obvious that guy needed IV antibiotics the first time they dressed that wound. How they could let him go for more than 24 hours is beyond me. Seems very convenient to let him stay with a gaping wound, and pull James after only a few days. This could point, however, to them learning the extent of Jonathan's infection or the type of microbes out there on the island.

They can easily start an IV, take some labs, start some IV antibiotics, give them every 12 hours and keep the game going. They can't do surgery out there, but any IV antibiotic or supply can be available in 24 hours.

Just sayin.