U.S. Sens. Dianne Feinstein (D-Calif.), Kirsten Gillibrand (D-N.Y.) and Elizabeth Warren (D-Mass.) have written a July 28, 2014, letter to Food and Drug Administration (FDA) Commissioner Margaret Hamburg, requesting additional information about how the agency plans to implement and evaluate new policies designed to combat the spread of antibiotic-resistant bacteria. Noting that “four times as many antibiotics are used in food animal production as are used in human medicine,” the senators praise recent guidance intended to curtail the routine use of these drugs to promote animal growth, but question whether these measures go far enough.

“We remain concerned, however, that many of the remaining approved uses of antibiotics to contain and prevent diseases are not strictly defined, and still allow for the continuous administration of low doses of antibiotics,” they write, pointing to loosely-worded guidelines that approve antibiotics to prevent or contain disease “in times of stress.” In particular, the senators have asked FDA to clarify (i) how the agency intends to determine whether the non-judicious use of antibiotics in food animal production is declining; (ii) what steps the agency will take if it observes no change in the amount of antibiotics used for food animal production; (iii) how the agency will ensure that approved labeling indications do not pose the same risks of fostering resistance as the production uses now being phased out; (iv) how the agency plans to inspect facilities for veterinary feed directive compliance; and (v) how the agency plans to collect and compile data to track how specific antibiotics are being used.