Animal & Veterinary
Update On Extra-Label Use Of Fluoroquinolones
July 16, 1996
On August 18, 1995, the Food and Drug Administration (FDA) approved sarafloxacin hydrochloride for use in broiler chickens and growing turkeys for the control of mortality associated with Escherichia coli organisms susceptible to sarafloxacin. This approval raised concerns about the effect of these uses on the development of resistance to fluoroquinolones in humans. FDA addressed these concerns by asking veterinary practitioners to refrain from administering the fluoroquinolones for extra- label uses in major food-producing animals.
The FDA restriction on extra-label use of these drugs provides the Agency with an opportunity to assess changes in antimicrobial susceptibility from the labeled food- animal uses of fluoroquinolones and helps to ensure the continued effectiveness of this antibiotic. The Center for Veterinary Medicine (CVM) is committed to preserving the usefulness of the fluoroquinolones. Prudent and judicious use of these compounds, only for label-approved use, will be an important factor in retaining their effectiveness for veterinary use.
Expert scientific groups such as the Institute of Medicine and the American Society for Microbiology have expressed concern about the national and global increase in antimicrobial resistance and the complex issues surrounding this increase both in community and institutional settings. The rate of resistance development by human bacterial pathogens may be exceeding the rate of discovery and development of new antimicrobial drugs. The development of resistance in human pathogens results from direct use of antimicrobials in man and possibly the acquisition of resistance from animal and environmental bacteria.
The use of fluoroquinolones in animals, even when limited to therapeutic use, may facilitate the emergence of bacterial resistance. When this occurs in enteric pathogens, the potential for transfer to humans exists, especially through food. Cross-resistance occurs throughout this entire class of drugs; therefore, resistance to one fluoroquinolone will compromise the effectiveness of all fluoroquinolone drugs. Evidence from some European researchers indicates that quinolone-resistant bacteria, particularly Campylobacter jejuni and some strains of Salmonella, are emerging in treated animal populations. The use of fluoroquinolones in food animals is of particular concern to the human medical community because these drugs are used to treat a variety of serious infectious conditions. Food animal veterinarians, as part of the public health community, have a responsibility to avoid unnecessary or inappropriate treatment of animals with fluoroquinolones.
CVM is committed to resolving these public health concerns in a manner that both maintains the integrity of the use of the fluoroquinolones and yet minimizes the possibility of transference of resistant zoonotic organisms from animals to humans. The FDA, CDC, and USDA have established a national surveillance program to monitor changes in antimicrobial susceptibilities of zoonotic pathogens from human and animal clinical specimens, from healthy farm animals, and from carcasses of food-producing animals at slaughter plants. Veterinary testing is conducted at the USDA Agricultural Research Service National Animal Disease Center (NADC) in Ames, Iowa. Salmonella was selected as a sentinel organism to monitor. CDC's Foodborne Disease Laboratory in the National Center for Infectious Diseases will conduct the testing of human isolates, both Salmonella and Escherichia coli O157:H7, submitted by 14 State Public Health Laboratories.
The monitoring system will provide descriptive data on the extent and temporal trends of antimicrobial susceptibility in Salmonella from the human and animal populations. The goals of the monitoring program are to provide timely information to physicians and veterinarians in each arena; prolong the lifespan of approved drugs; facilitate the identification of resistance in either population as it arises; and identify areas for more detailed investigation. Early identification of emerging resistance will allow agencies to focus educational efforts in the human and veterinary medical communities on the appropriate use of antimicrobial agents.
As part of the monitoring effort we intend to share our knowledge with practitioners. CVM is initiating an information and education campaign to assist practitioners in preserving the usefulness of fluoroquinolones and requesting their ideas and enlisting their aid in safeguarding the use of this class of drugs. Our policy to restrict extra-label use of these drugs was initiated to minimize the emergence of resistance in animal species for which fluoroquinolones are not yet approved and to prolong drug effectiveness of approved uses by promoting use according to labels which have met the scientific rigors of the approval process.