How did your vet happen to come to that diagnosis?
1. Did he do bloodwork?
2. Did he do a C&S?
They died of cellulitis? come on....
I'm assuming that you atleast took photos of the dead geckos, right? If they had such advanced cellulitis that it caused them to die....this should be pretty obvious in the photos.
Anybody ever see a leopard gecko with strep throat? Me neither