After Decades of Antibiotic Treatment of Honeybee Colonies, Tetracycline-resistant Bacteria Often Found in US Bees

After years of preventive treatment with antibiotics, the guts of domesticated honeybees in the United States harbor numerous genetic variants that confer resistance to the antibiotic tetracycline, a recent study found. Image: Agricultural Research Service/Jack Dykinga

First it was pigs and chickens that were found to harbor antibiotic-resistant bacteria as a consequence of widespread use of antibiotics in the animals for preventive purposes. Now researchers have discovered that honeybees similarly exposed to antibiotics for decades carry bacteria in their guts that are resistant to tetracycline, according to a study published online today in the journal mBio.

The finding of antibiotic-resistant bacteria in honeybees doesn’t pose a direct threat to human health because these bacteria are not found in the honey produced by the bees. But the study provides insights into the consequences that widespread antibiotic use can have on gut flora and health in another species.

For more than 50 years, US beekeepers have applied oxytetracycline to honeybee colonies to prevent a bacterial disease called foulbrood. To assess the effect of this use on the gut bacteria of bees, a team of researchers used genetic sequencing and other techniques to compare bacteria in the gut of US domesticated bees, wild bees (which presumably wouldn’t be exposed to the antibiotic), and domesticated bees from parts of Europe and New Zealand where use of antibiotics on bees has been forbidden. The researchers found that gut bacteria in US bees carry 8 genetic variants that confer resistance to tetracycline, compared with 1 or 2 such resistance-conferring variants in wild bees or in those from countries that don’t use antibiotics on bees. Continue reading