20. Salmonella resistance
Jeff understood that any and all use of antimicrobials could lead to the development of resistance. "But," he asked, “what kind of evidence is there that demonstrates that use of antimicrobial agents in food animals can affect human infections?"
Dr. Douglas was quick to explain the mounting evidence from the public health community. One example he provided was the increasing fluoroquinolone resistance in Campylobacter isolates from humans, which followed the approval of fluoroquinolone use in poultry. (See graph below)
Although resistance was present prior to the use of flouroquinolones for poultry in the United States, the graph shows a significant increase in the proportion of Campylobacter isolates resistant to fluorquinolones following the drug's approval for poultry. Flouroquinolones began to be used in poultry in other countries in the early 1990s. Many of the early US cases occurred in travelers to those other countries. The concern about emergence and spread of fluoroquinolone-resistant Campylobacter led the U.S. Food and Drug Administration (FDA) to do a risk assessment of fluoroquinolone use in poultry. The results from this risk assessment lead FDA to withdraw licensure for fluoroquinolones in poultry in 2005. For more information on this case, please see the sidebar.