>  I do not see how a hive that never gets foulbrood due to preventative
> use of terramycin, could then develop resistant bacteria.

Pete, I feel that you are exhibiting Lamarkian reasoning  : )

Bacteria don't become resistant from exposure to antibiotics.  They
become resistant by mutation, or by incorporating plasmids or viral
genes.

Constant exposure to TM, as with grease patties, may accelerate the
development of a resistant bacterium, due to opening up an unexploited
niche, or by avoiding competition with resistant bacteria.

But it only decreases the interval for such resistance to occur.  With
regular "prophylactic" treatment, resistance will also surely occur
eventually.

The reason that we didn't notice such resistant AFB until grease
patties were used was because the resistant bacteria pay a metabolic
cost, and are quickly bred out when there is no active TM in the
colony.

Now Pete, I'm playing Devil's advocate here.  Many of us used TM dust
religiously spring and fall year after year, and it worked great.  But
I must agree with Trevor, that if you aren't careful, you can easily
contaminate your whole operation with AFB when you use antibiotics by
calendar, and don't remove infected combs immediately.  I've done it
myself, more than once!

If I were a large commercial beek, I would likely use TM regularly.
There are some currently applying both antibiotics simulataneously,
which I cannot support.

However, since a large part of my income is from the sale of nucs, and
since I don't want to be buying back nucs that come down with AFB, I
tend to use antibiotics minimally so as to flush out any infected
colonies and burn the frames.

My question is:  am I now paying the price for this with a resurgence
of EFB in my operation?  That's why I'm having tests run to see if I
indeed have EFB, or whether it is something else.

In the meantime, I'm (obviously) breeding from colonies that don't
exhibit signs of disease.

Randy Oliver

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