> the use of the very effective Terramycin extender 
> patties saved many beekeepers money in the short 
> term, but quickly led to the development of OTC-resistant AFB.

There is a lot of misinformation surrounding the OTC-resistant AFB. Resistance did not come about quickly. TM was first used in the 1950s, but did not become widespread until Sulfa was prohibited on bees in the 1970s. Resistance was first detected in Argentina in 1996. By 2000 it had been detected in 24 US states. Jay Evans wrote in 2003:

> Tetracycline resistance in North American populations of P. larvae has become widespread only in the past decade, despite long-term use of this antibiotic.

He does not link it with a particular practice. The resistance could have come from other bacteria through Lateral Gene Transfer.

> Tetracycline resistance from widespread areas appears to reflect independent origins of this trait over a short time pe- riod. Tetracycline resistance might be epigenetic in nature, specifically through the presence of plasmids and mobile genetic entities that produce proteins involved in resistance 

By the way, there have been reports of resistance to Sulfa drugs as well:

> Plagemann, O. (1991). Sensitivity of Bacilluslarvae to antibiotics and sulphonamides. Tieraztliche Umschau,46: 24-27. (ln German.)

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