Cutting the prey's nails (or teeth, if they stick out) is a good idea- that's about the only way to prevent an unlikely infection like this. I've been keeping many snakes for a long time & I've never had this happen- at least not that I was aware of. At least the swelling tipped you off so you could give antibiotics. I agree that a snake that's eating normally will usually replenish their gut bacteria pretty fast. It's mostly when they've been medicated multiple times or with multiple medications that probiotics can help them come back faster- especially when they're having obvious trouble digesting. I'm so glad that Poppy's recovering so well & so quickly.And good on you for getting him to the vet so quickly. I think that really helped too.