I'm not sure URI are contagious (I think it's usually a husbandry problem that allows it to set in) but I would practice quarantine with the guest dragon, since it may be of questionable health. Keep it in a completely separate room, handle, feed and clean his cage last after all your own animals. Wash you hands thoroughly and change clothes when you are done.
Poor little one that must have been a horrible shock for you.
Beardies with a UYI can possibly infect other dragons that are healthy. I would quarantine him as taterbug said away from other dragons in the house. I would not handle him without washing your hands well before and after. Keep all of this things separated from your other dragons things also so you don't cross contaminate.
unfortunately he passed away.
he was very very ill, i took him to the vet yesterday after he was gurgling and gasping and my vet said he had full blown pneumonia.. wasn't much hope but I bought the antibiotics anyways.
atleast i tried...
I hope the family that owns him is not to upset. You did what you could but in the conditions he was in, its not surprising and with a URI. At least hes not suffering anymore the poor thing. I am sorry this happened while he was in your care but I also know he was brought to you sick.