Esp Griffyn
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Uh, no, he died of liver failure.
First of all, there is an inaccuracy in the post above yours, not even touching on the point about being "open to 700 bacterias" etc, which is a minefield of inaccuracies in itself, but the treatment for necrotising fasciitis is not "amputation", it's usually surgical excisement, but it can also be treated with larval biosurgery in some cases. Amputation would be left for the most extreme of cases, which is actually relatively few.
I did my Bsc (Hons) dissertation on larval biosurgery appilcation modus for NF, so I read a fair bit on it.
Jeff did die of liver failure, but systemic illness is a common effect of Brown Recluse bites, and a common effect of NF. While your body is giving all it's got to fend off the bacterial infection that is destroying the tissue in the wound, immense stress is put on the other organs of the body. It completely wipes you out - no doubt aside from the issues of arm muscle strength and stamina barring Jeff's return to Slayer, he would have been feeling wiped out for the last two years. Lethargy, high susceptibility to infections, taking a long time to hear wounds and clear infections, messed up appetite, mental depression etc.
While drinking beer would likely not have helped in this state, I would not begrudge the guy his booze, it's hard to argue that the spider bite was not the eventual cause of his death, even if the way it claimed him was convoluted.