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Date: | Thu, 2 Dec 1999 10:44:39 -0600 |
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Hi Everyone,
I have to comment on this.
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Blane White
MN Dept of Agriculture
[log in to unmask]
>>> Allen Dick <[log in to unmask]> 12/01/99 08:56AM >>>
>I've been thinking about the new oxytetracycline resistant ABF that
has suddenly
>been appearing in numerous places and which seems to be spreading,
and realise
>that beekeepers don't realise that it is a =whole new disease= (more
on that
>below). As such it deserves and new name, and in honor of where it
first
>appeared, I'll call it South American Foul Brood or SAFB for short.
I suggest we call it bad AFB in honor and memory of Andy N. and his
Bad and Sad bees.
>Only a few years ago, a noted American researcher reportedly
investigated
>contemporary AFB compared to AFB that had been in storage for many
years and
>concluded that there had been little, if any, change in response to
>oxytetracycline over the years: oxytet worked as well as ever. Then
we heard
>that AFB in Argentina was exhibiting resistance to traditional
drugs. Now we
>have found resistance in the USA and Canada. I am sure it will
appear worldwide
>shortly -- at least wherever Argentinean honey is imported and
sold.
Hold on Allen. There were reports of OTC resistance in Argentina at
least as far back as 1989 well before that study was published. In
fact OTC resistance was found in the US for the first time within a
year of the publication of that article when an inspector found some
AFB that was responding to treatment and sent in a sample for testing.
We would have found it earlier if we had thought to send in the right
samples and asked for the testing. Good thing that inspector though
of it or we would not have understood what was going on at the time.
>That is not to say that all resistance necessarily originates in the
Argentine,
>but we do know that AFB can be very contagious in the absence of
resistant bees
>or drugs that are effective, and we do know that honey carries AFB
spores very
>nicely. We also know that honey is 1. discarded in open sites, 2.
honey drums
>are re-used, sometimes without washing for feeding bees, 3.
hobbyists (and
>occasionally commercial beekeepers) sometimes purchase honey to feed
their bees.
>You don't have to be a rocket surgeon to figure out the rest...
>What I learned watching TV last night was that micro organisms swap
DNA on a
>regular basis when they come into contact with one another and that
resistance
>in one bacterium can and will transfer into others that come into
contact. This
>may explain why suddenly we are seeing resistance appear all over
the place in
>types of bacteria that have previously been isolated and very
limited in their
>habitat such as those causing AFB; perhaps they are meeting more
ubiquitous
>types of bacteria that are resistant and the resistance is
transferring.
>Apparently many types of bacteria associated with livestock
operations are now
>resistant to many antibiotics and it is not hard to see how AFB
organisms
>(notice how I avoid naming them) could have come into close
contact.
Again hold on there! First horizontal gene transfer ( the process
referred to above ) appears to not be that frequent of an event and
requires close contact between the organisms involved. Second the
rise of antibiotic resistance does not require such transfer nor
mutation. Simply using an antibiotic will select for those organisms
in the target population which have such resistance. Each and every
use of the antibiotic will select for resistance that is already in
the population. In fact here resistance appeared first in those
beekeeper's outfits who were most diligent in their treatment program
i.e. they subjected the population of AFB in their hives to the
strongest selection for resistance. Another observation is that
resistance appeared a few years after the widespread use of TM
extender patties which hold the antibiotic in the hive for extended
periods of time in an active form hence vastly increasing the
selection for resistance. In short, we probably have imported some
but we almost certainly also selected some of our own.
Now reread that stuff above on selection and use pesticide instead of
antibiotic and you have a pretty good description of how varroa
resistance to apistan or other treatments develops. The development
of resistance in both cases involves very similar mechanisms.
And I agree one of the keys to getting off the chemical treadmill we
have created here in North America is the widespread use of resistant
stocks of honey bees.
Good discussion and very relevant.
blane
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