Bacterial DNA taken from soil samples collected between 1940 and 2008 in the Netherlands revealed a rise in the level of antibiotic resistant genes, said David Graham, a professor at England's Newcastle University.
Scientists fear a resistant gene in a harmless bacteria could be passed to a disease-causing pathogen, Graham said in this month's issue of the journal Environmental Science and Technology.
"The big question," Graham said, "is that with more stringent European regulations and greater emphasis on conservative antibiotic use in agriculture and medicine, why are antibiotic resistant gene levels still rising?"
Graham said he and his team expect to find similar results when they expand their study to include soil samples from other parts of the world.
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