Ok, here's how it works:

Your bee is carrying spores in its honey stomach. The spores wind up being mixed with the larval food. When the spores are in the larval gut, they begin to hatch out, producing the vegetative stage. If conditions are favorable these produce tons of other spores, the process repeats, the larvae get sick and die. The bees eat the dead larvae and spread the spores everywhere.

But if there is also antibiotic in the food supply, the scenario changes to this: The spores and the antibiotic are fed to the larva. They begin to hatch, but the antibiotic prevents the vegetative stage. Pretty soon all the spores have hatched, no new spores are produced the disease symptoms are not produced, the hive does not get sick. The spores are gone. 

Your example of a hive breaking down with AFB 15 months later begs the question of whether it was a recurrence or they picked it up from somewhere else. However, if TM was being used as a routine, it would not have broken down again at all. 

As I have said repeatedly, I understand the rationale behind never using antibiotics and burning any hives that break out with AFB. I also think that routine use of antibiotics in hives is cheap, effective, and produces no harmful effects to humans or bees. It certainly plays no role in the development of resistance in human bacterial. By and large that is a problem in hospitals where there are large numbers of sick individuals in proximity being constantly dosed with ever stronger drugs.

Again, the key (I think) is to have a large reservoir of sick individuals where the resistant bacteria can develop. I just don't imagine the likelihood of resistant strains developing among hives that don't have AFB. But I am listening to anyone who can demonstrate the facts. I certainly give credence to actual field experience over theoretical thought experiments.

PLB

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