TDK conference 2015

American foulbrood caused by Paenibacillus larvae has the greatest economic importance among the European honey bee diseases. The causative agent and the notifiable disease occur worldwide, also in Hungary. Paenibacillus larvae is a Gram-positive spore-forming bacterium species. The resistance of its spore is very high, and it preserves its virulence for decades. American foulbrood is a disease of the bee brood, which spreads fast in the colony and between colonies. Currently there is no effective treatment of the disease. Prevention of the clinical form of the disease and the reduction of the number of spores in the bee hive are aimed. Using antibiotic treatment of sick colonies is forbidden in Hungary. The colonies showing clinical signs have to be killed, and the apiary gets quarantined. In 2014 approximately 20.000 apiaries cultivated 1.112.000 colonies in the country, which produced 17.000 tons of honey, which was mainly exported. Last year there were 151 outbreaks in the country due to American foulbrood, there where quarantines in 680 settlements, more than 4.000 colonies had to be killed, which cost 365,6 million HUF for the state as a compensation. These data show the economic impact of this serious problem in Hungary.

Our purpose was to create a representative bacterial culture collection of Paenibacillus larvae in Hungary, in order to study the features of the Hungarian isolates (virulence variants, serotypes, phenotypic and genotypic characters, susceptibility against disinfectants), and thereby to find an effective solution against the disease.

A total of 297 honey samples were collected from different parts of Hungary (19 counties, 142 settlements and Budapest), and different cultural methods were used for the isolation of the causative agent. Based on the cultural, morphological and biochemical features 85 isolates were cultured and stored in freezer at -80 °C till use. Identification of the isolates on species level was carried out using MALDI-TOF (Matrix-assisted laser desorption/ionization Time-of-Flight) mass spectrometry, which identified all isolates except three as Paenibacillus larvae.

As a result of our work the participating apiaries got information about the infection of their colonies with the causative agent of American foulbrood, and a representative bacterial culture collection was set up, which contains 82 Paenibacillus larvae isolates from different parts of Hungary (17 counties, 48 settlements and Budapest). This bacterial culture collection serves a basis of further research.