Bacteria in the guts of honeybees are highly resistant to the antibiotic tetracycline, probably as a result of decades of preventive antibiotic use in domesticated hives. Researchers from Yale University identified eight different tetracycline resistance genes among U.S. honeybees that were exposed to the antibiotic, but the genes were largely absent in bees from countries where such antibiotic use is banned. The study appears on October 30 in mBio, the online open-access journal of the American Society for Microbiology.
"It [resistance] seems to be everywhere in the U.S.," says Nancy Moran of Yale University, a senior author on the study. "There's a pattern here, where the U.S. has these genes and the others don't."
Honeybees the world over are susceptible to the bacterial disease called "foulbrood", which can wipe out a hive faster than beekeepers can react to the infection. In the U.S., beekeepers have kept the disease at bay with regular preventive applications of the antibiotic oxytetracycline, a compound that closely resembles tetracycline, which is commonly used in humans. Oxytetracycline has been in use among beekeepers since the 1950s, and many genes that confer resistance to oxytetracycline also confer resistance to tetracycline.
Using sensitive molecular techniques, Moran and her colleagues screened honeybees from several locations in the United States and from Switzerland, the Czech Republic, and New Zealand as well as several wild bumblebees from the Czech Republic, for the presence and abundance of tetracycline resistance genes. They found that U.S. honeybees have greater numbers and a more diverse set of tetracycline resistance genes than honeybees from the other countries.
Moran says it is reasonable to expect to see widespread resistance among bees, considering the decades-long use of oxytetracycline in honeybee hives. "It seems likely this reflects a history of using oxytetracycline since the 1950s
|Contact: Jim Sliwa|
American Society for Microbiology