> Antibiotics have been used for the prevention of foulbrood since the 
> 1940s. I have personally used them since the 1970s. I have officially 
> inspected large outfits where antibiotics are routinely used to prevent 
> foulbrood > and outfits where they are never used. I reckon I have a 
> pretty good idea how they work.

It might mask the AFB but it doesn't cure it.  There was a study done here 
in Australia back in the early 1990's, I recall, where AFB infected hives 
were given a dose of oxytetracycline.  In the hives, it looked good for a 
while and the clinical symptoms were gone but those hives did break down 
with AFB at a later stage.  Some took up to 15 months.

There are many stories of beekeepers who have used oxytetracycline for years 
and then stopped, having a breakdown of hives with AFB.  I have in fact 
asked many American beekeepers if you stopped using the oxytetracycline what 
would happen?  Most say their hives would breakdown with AFB.  So it might 
stop hives exhibiting clinical signs but it certainly does not cure it.

Here in Australia we had very little AFB until EFB turned up and beekeepers 
started using oxytetracycline.  There are many cases of beekeepers about to 
use oxytetracycline and getting a lab test on the infected brood only to 
find they had AFB and not EFB.  You might say that they should know the 
difference but there are some beekeepers who do not.  Some are only honey 
grubbers and don't go down below the excluder and thus don't do brood 
inspections.  So much easier for these to just give a dose of 
oxytetracycline every so often and get on with producing honey.

So back to the original theme where it was suggested that dosing up swarms 
with oxytetracycline implying it would stop that hive from getting AFB. 
Again I would reiterate that if the oxytetracycline only kills vegetative 
stage, then the bees would need to store the antibiotic and use it when the 
AFB spore vegetated to be useful.  If all the antibiotic was consumed, then 
there would be none left to kill the vegetative stage at a later date.

Trevor Weatherhead
AUSTRALIA 

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