We have discussed the issue of terramycin resistant foulbrood numerous times here on Bee-L. Working as an NY State bee inspector I found that TM resistant AFB was exceedingly rare and seemed to be traceable in my territory (ten counties) to a single beekeeper. This person was notorious for treating active raging cases. 

Over time I concluded the most likely scenario for the development of TM resistant AFB is this: you have multiple infected colonies that you simply treat with TM until the symptoms die down. They appear healthy for a while and then it recurs, so you treat some more. The more virulent strains would tend to survive this battle.

I don't believe that resistant strains are anywhere near as likely to develop in hives where the terramycin is used to prevent disease, simply because you would not have an active evolving population of disease. In other words, how can the disease evolve if it never occurs? -- as is the case with preventive use of TM.

I saw outfits where TM patties were used year round and there simply was no foulbrood. With no foulbrood present, how could resistant foulbrood evolve? Whereas, in an outfit where it is already rampant, the constant dosing would be a recipe for generating resistance, IMHO.

All the same, I understand the rationale for not using antibiotics at all make perfect sense. No resistance to antibiotics will occur if you burn the hives that break down. On the other hand, if you don't use antibiotics, why would you care if there was resistance or not? Not your problem.

PLB

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