One of my pigs took chloramphenicol a few years ago. I had the same gloving precautions as you were given, although it was explained to me that the risk of this was small even if I was taking a human dose myself, and even less from potential skin contact, though still possible.
From my understanding, it's not used as first-line med in humans anymore because of a small but serious risk of aplastic anemia developing after use (basically the bone marrow stops making cells.) This is really serious, potentially fatal. It also can't be used in animals in the food industry because of the risk of humans ingesting meat containing the drug and theoretically being exposed that way. My vet said that the aplastic anemia risk really isn't there in animals and that it's safe to use in guinea pigs (who have less antibiotics available to them generally because so many things safe for us upset their gut flora to a dangerous extent.)
I get feeling cautious about it, though, and you can always ask your vet if there's something else to try first. If this has been resistant to treatment in the past, though, it may have been chosen because you are running out of antibiotic options and there may not be a lot of other options available.