Broad-spectrum antibiotic their greater potential to disrupt a larger variety of normal human flora. After continued exposure to an antibiotic, bacteria may develop changes in their structure or function that make them resistant to the antibiotic. These resistant organisms will live, while the susceptible organisms will die, leaving the population of bacteria entirely resistant to a given antibiotics. For example, after the discovery of penicillin and its subsequent use to treat bacterial infections, bacteria were found to have begun producing an enzyme, penicillinase, which rendered the penicillin molecule inactive. In response to this newly-acquired resistance, newer penicillins were produced that could not
Antibiotic use in livestock for not collecting enough information and data on antibiotic use in factory farms. From this, the GAO concluded that the FDA does not have enough information to create effective policy changes regarding antibiotic use. In response, the FDA insisted that more research was being conducted and voluntary efforts within the industry would solve the problem of antibiotic resistance. Few policies exist that limit antibiotic use on factory farms, and some proposed legislation in the US has failed to be adopted. In 2007, two federal bills (S. 549 and H.R. 962) aimed to phase out nontherapeutic antibiotics in U.S. food animal