E. coli bacteria have already shown some resistance to gentamicin, a heat-stable antibiotic.   And sulfamethazine, a sulfonamide antibacterial, is one of the most common animal drugs used on dairy farms.

The U.S. Food and Drug Administration has not established any tolerance level for gentamicin in the edible tissues of veal calves.  But when checking up on a bob veal calf sold by the Robert L. Beckman dairy farm at Cassadaga, NY, tissue samples returned residues of gentamicin in the liver, kidney, and muscle tissue of the animal.

In a July 9 warning letter to Beckman, FDA said the presence of the drug in the edible tissue of the animal causes the food to be adulterated under federal law.

“Our investigation also found that you hold animals under conditions that are so inadequate that medicated animals bearing potentially harmful drug residues are likely to enter the food supply,” FDA said in the letter.

The agency told Beckman his treatment records are not be properly maintained, and the dairy farm is using Gentamicin Sulfate in ways not provided for on its label.  Such “extra label” use of an animal drug is allowed only under the supervision of a licensed veterinarian.

FDA said Beckman “administered gentamicin sulfate to a bob veal calf without following the animal species as stated in the approved labeling.”

Meanwhile, a Maple Park, IL dairy farm received a warning letter from the FDA about its alleged misuse of the animal drug sulfamethazine.  Owners Brian and Barbara Hill sold a dairy cow for slaughter as food, according to FDA, that had 2.649 parts per million (PPM) of sulfamethazine residue in the liver tissue.

The FDA established tolerance of 0.1 ppm for residues of sulfamethazine in the uncooked edible tissue of cattle.

In the letter, FDA said the Hills “did not use sulfamethazine boluses as directed by the approved labeling.”

The label instructions for the drug clearly state that it is not to be used for female dairy cattle 20 months of age or older.

USDA’s Food Safety and Inspection Service (FSIS) did the tissue sampling for both the bob calf and the dairy cow.  Some fear animal antibiotics in food are making some antibiotics in humans ineffective.

Each dairy farm was given 15 working days to respond to its FDA warning letter.