The Food and Drug Administration announced it would no longer allow distribution or use of the antimicrobial enrofloxacin after judging that it causes resistance in Campylobacter jejuni when used to treat respiratory infections in poultry. The ruling does not affect other approved uses of the drug. Enrofloxacin belongs to a class of drugs known as fluoroquinolones and is marketed by Bayer Corporation under the name Baytril.
Chickens and turkeys can harbor C jejuni in their digestive tracts without causing poultry to become ill. The FDA reported enrofloxacin does not completely eliminate the organism from the birds' intestinal tracts, and those bacteria that survive are resistant to fluoroquinolone drugs. The agency stated that the resistant bacteria multiply in the digestive tracts of poultry and spread through transportation and slaughter, and are found on chicken carcasses in slaughter plants and retail poultry meats.
A reported national increase in fluoroquinolone-resistant Campylobacter infections in people led the FDA's Center for Veterinary Medicine to ask Bayer in October 2000 to voluntarily withdraw the product. In December 2000, in response to a notice of an opportunity for a hearing, the AVMA submitted an evaluation of the scientific reasoning behind the FDA's action (see JAVMA, May 15, 2002). The Association recommended that a hearing be conducted so that the scientific evidence could be presented. At that time, the animal drug was used in less than 1 percent of chickens, when serious disease threatened flock health. The AVMA is concerned that the withdrawal of the drug will negatively impact poultry health and welfare. The alternatives to enrofloxacin are few in number and less effective.
Bayer can appeal the withdrawal to a U.S. Court of Appeals within 60 days from the date of the final decision, July 29. The final rule to withdraw approval of the antimicrobial for treating bacterial infections in poultry will be effective Sept. 12. For the final decision, log on to www.fda.gov/oc/antimicrobial/baytril.pdf.