Each thread is organized with the latest dates first. Please be aware that information changes over time. That provided in earlier discussions may no longer be current; it is displayed as originally published. Furthermore, the author of APIS is not responsible for articles written by others that are linked here. The main intent is to provide historical perspective and a wider view of issues.

Those links not derived from the APIS page are marked with a not with a .

American foulbrood (AFB) is one of the most important beekeeping diseases. It is caused by the spore-forming bacterium, Bacillus larvae. The spores are resistant to heat and drought and can remain dormant many years.

For decades, the use of bee inspection and fire in combination were the only things used to fight American foulbrood until antibiotics came along. Now, Terramycin® a tetracycline product, is labelled and used extensively to control the disease. There is evidence, however, that the bacterium can become resistant to antibiotics. This has been seen in Argentina.

The use of extender patties to administer Terramycin® has provided another possibility as noted by the following message posted to the Bee-L Discussion list:

Date: Mon, 4 Nov 1996 12:55:53 -0800
From: "Kerry Clark of AGF 784-2225 fax (604) 784 2299"
Subject: Re: antibiotic resistant AFB

The spores of the bacteria that causes AFB (Bacillus larvae) are viable for decades. A couple of years ago, the susceptibility to oxytetracycline HCL (the active ingredient of Terramycin®) of cultures from old spores (1924) was compared to the susceptibility of cultures from current (1994) spores.

Shuimanuki H and D. Knox. 1994. Susceptibility of Bacillus larvae to Terramycin. ABJ Vol 134 No 2 p 125-126.

Current AFB was found to be just as susceptible as old-time AFB. That result seems better than should have been hoped for, since beekeepers' use of oxytetracline for 40 years was sometimes nearly a recipe for developing bacterial resistance (ie. half-treat active beekeepers' use of oxytetracline for 40 years was sometimes nearly a recipe for developing bacterial resistance (ie. half-treat active infections, use the same product all the time, use uneven or haphazard doses, then throw the half-empty package in the truck til next year, etc.). For some reason, resistant strains didn't survive in the field (or maybe they were infrequent enough that beekeepers weeded them out after the hives died).

There's been a recent change, though, that makes the appearance of oxytetracycline resistant AFB more likely: widespread, nearly continuous use of antibiotic extender patties. This is the one ingredient that was missing: a continuous selection pressure.

While continuous vegetable oil patties may be recommended for tracheal mite control, and while the same patty can be used to apply antibiotic, antibiotic extender patties should not be used for months at a time. (The vegetable oil (not the antibiotic) is the active ingredient for tracheal mites). Long-term (months) continuous use of antibiotic extender patties can result in antibiotic residues appearing in an extracted honey crop, and will act to select antibiotic-resistant strains of AFB.

Antibiotic extender patties can be a useful tool to apply oxytetracycline, but should be used (where they are permitted) only for short periods (just as other methods: medicated syrup, dry application, etc. would be used).

Kerry Clark, Apiculture Specialist
B.C. Ministry of Agriculture, Fisheries and Food 1201 103 Ave
Dawson Creek B.C. V1G 4J2 CANADA
Tel (250) 784-2231 fax (250) 784-2299
INTERNET kclark@galaxy.gov.bc.ca

Bee inspection and fire are routinely used in cases where symptoms occur in Florida.

Any colony with symptoms (scale, broken down larvae, perforated cappings, characteristic odor) must be burned. The state of Florida pays an indemnity to beekeepers for each colony the bee inspector is forced to burn.

Control of American foulbrood without drugs; New Zealand case, February 2000.

Antibiotic-resistant foulbrood and bee inspection, January 2000.

American foulbrood historical perspective; management using drugs; evidence of resistance to antibiotics, November 2000.

Re-examining tetracycline for AFB control, November 1998.

Long-term Terramycin® use: Prescription for resistance to Paenibacillus larvae?, September 1997.

Asks whether American foulbrood is on the rise and why this might be so, May 1996.

Discussing New Zealand's disease control proposal, focuses on bee inspection and the number of spores need to infect a colony, August 1996.

Article in American Bee Journal on recipes for antibiotic extender patties using Terramycin®, September 1994.

Discussion of the usefulness of bee inspection with reference to Florida regulations, November 1992.

Discussion of antibiotic extender patty labelling for AFB control, August 1992.

History of antibiotic extender patty and labelling for AFB control,  July 1992.

Discussion of the value of bee inspection efforts; historically and present day with emphasis on AFB control, August 1991.

More AFB found in Florida; discussion of issues, May 1990.

American foulbrood found in Argentina; Brazil's concerns; New Zealand's programs, November 1989.  

Discussion of resistance buildup in antibiotics or pesticides, December 1987.

Return to top of page

Copyright © 1999 M.T. Sanford, "All Rights Reserved"