HCR Update from Mark Sanna: A federal analysis of 30 antibiotics used in animal feed found that the majority of them were likely to be contributing to the growing problem of bacterial infections that are resistant to treatment in people, according to documents released Monday by a health advocacy group. Scientists from the F.D.A. studied 30 penicillin and tetracycline additives in animal feed. They found that 18 of them posed a high risk of exposing humans to antibiotic-resistant bacteria through food.