These findings raise the question of whether antibiotic resistance genes in bacteria in the food supply could be transferred to bacteria in the human gut. For example, you feed a pig antibiotics for a large part of its life. The bacteria in the pig's digestive tract become resistant to antibiotics. You slaughter that pig and send it to market. The bacteria end up on the meat products.
Horizontal transfer can take place in as little as an hour.
Antibiotic resistance in Bacteroides does pose a threat to human health. These bacteria often cause post-surgical infections, and these infections are increasingly becoming resistant to antibiotics commonly used to treat them, such as clindamycin, which is in the same family of antibiotics as erythromycin. Another concern is that Bacteroides may pass these antibiotic-resistance genes on to other bacteria that can cause human disease. We know from laboratory studies that one catalyst that triggers horizontal gene transfer is the antibiotic tetracycline. Tetracycline is like an aphrodisiac for Bacteroides, causing it to transfer its resistance genes.