NRCS has developed a number of plant-based, water extracts which have shown very effective results in controlling, and eradicating, both bacterial pathogens that are the cause of American Foulbrood (AFB) and European Foulbrood (EFB) in laboratory tests.
These plant extracts are known to be harmless to adult honeybees but have shown remarkable effects against both the biofilm, and the endospores of Paenibacillus larvae, the pathogen responsible for AFB, and the bacterial pathogen, Melissococcus plutonius, responsible for EFB.

American foulbrood (AFB) is the name given to a disease that results in the decimation of the honey bee larvae and the eventual collapse of the colony. The condition is caused by a pathogen, Paenibacillus larvae, a gram-positive bacterium. Only honey bee larvae are affected by this pathogen.
The bacterium has several defense mechanisms that shield it from the normal control agents, such as the medically important antibiotics like oxytetracycline, lincomycin and tylosin.
These mechanisms include its ability to form biofilm and endospores. Biofilm, in simple terms, is a thin, slimy film of bacteria and bacterial secretions that physically attaches itself to surfaces and is difficult to completely eliminate. The biofilm provides protection to the bacteria that live within it and make it difficult for control agents to penetrate and eradicate the bacteria.
It also protects the bacteria from harsh environmental conditions. This bacterium also has the ability to form endospores. To quote from the Symbiosis website: (https://www.synbiosis.com/support/glossary/definition/?term=Endospore)