Originally published in the February 2015 issue of Veterinary Practice News Choosing the right antibiotics—or whether to prescribe them—is far from a straightforward matter, and as concern grows over excessive antibiotics use, there’s a lot to consider. From the start, veterinarians are taught the correct use of antibiotics, which includes making a proper diagnosis, taking cultures and assessing sensitivities to choose the right antibiotic. It’s the next step in the process that becomes more difficult for veterinarians, said clinical pharmacist Sue Duran, RPh, MS, Ph.D., a fellow in the American Society of Health-System Pharmacists and the chairwoman of the board certification committee for the International College of Veterinary Pharmacy. “Both human and animal clinicians experience peer pressure from owners to prescribe antibiotics for their patients,” said Duran, a clinical pharmacist with the Auburn University College of Veterinary Medicine. J. Scott Weese, DVM, DVSc, Dipl. ACVIM, said pinning down the “whys” behind antibiotics overprescribing is difficult. “There are various reasons unnecessary prescribing can happen,” said Weese, an associate professor in the department of pathobiology at the University of Guelph’s Ontario Veterinary College in Canada. In some cases, antibiotics are used without a reasonable suspicion of a bacterial infection, such as a viral infection, he said. This can occur due to a lack of consideration of the disease process, inadequate use of diagnostic testing, client pressures or the perceived need to “do something”—the perception that if veterinarians don’t use antibiotics and a bad outcome results, it’s the practitioner’s fault, but the drug is at fault if a complication from antibiotics develops, Weese added. The American Veterinary Medical Association’s take: “When the decision is reached to use antimicrobials for treatment, control, or prevention of disease, veterinarians should strive to optimize therapeutic efficacy and minimize resistance to antimicrobials to protect public and animal health and well-being.” To develop practice guidelines for implementing better “antimicrobial stewardship in companion animal practice,” AVMA has created its Task Force for Antimicrobial Stewardship in Companion Animal Practice. The panel of 10 AVMA subject-matter experts will meet over a 12- to 18-month period. Those invited to select and send participants include the American Animal Hospital Association, the Canadian Veterinary Medical Association, the Infectious Diseases Society of America and the Animal Health Institute. Representatives from the Centers for Disease Control and Prevention and the Food and Drug Administration also will be invited. Christine Hoang, DVM, MPH, assistant director in the AVMA Scientific Activities Division, described the goal of the task force. “We don’t really know if veterinarians unknowingly prescribe too often,” Dr. Hoang said. “We hope to have a better understanding of prescribing practices in companion animal practice as a result of current efforts by our task force.” More knowledge and guidance are just what Weese wants to help veterinarians make decisions on antibiotics. “One problem we have is a lack of good studies about proper antibiotic use,” Weese said. “As opposed to the situation in human medicine, where treatment regimens are often based on large, well-designed studies, we often have little information to turn to. Principles of medicine and antibiotic therapy can help us make logical treatment recommendations, but more data would help us optimize antibiotic use – improving patient care while reducing the risk of resistance and adverse effects.” In the absence of such studies, Weese turns to the the catchphrase: “Think before you prescribe.” “Sometimes we prescribe by rote, without thinking about whether antibiotics are needed, what drug should be used, how long it should be used, whether there are nonantibiotic alternatives, whether antibiotic therapy has a chance of working without addressing an underlying problem, and similar aspects,” Weese said. The mechanics of approaching antibiotics prescriptions is often complicated by other factors, Duran noted. The pressure veterinarians feel from pet and animal owners to prescribe antibiotics to an ailing patient must be dealt with, and at the same time practitioners face making medical decisions regarding what antibiotics to prescribe without all the information they would like to have, Duran said. “It takes time for the culture to be performed and come back to the veterinarian, therefore an antibiotic choice has to be made prior to all the scientific information,” she said. Duran noted pushes by the federal government and a number of research grant sources to develop faster tests to identify the bacteria and the best antibiotic for specific cases, but for now veterinarians must make do. Another consideration is that a pet owner may be unable to afford the best antibiotic for treatment, forcing the veterinarian to choose a less effective drug, Duran added. Resistance Antibiotic resistance is a big concern. “The more we use antibiotics, the greater the chance of resistance emerging,” Weese said. This resistance is a concern for pets, but the problem of resistance has taken a larger national debate when it comes to the use of antibiotics in food-producing animals. The CDC has found that wide use of antibiotics in food-producing animals contributes to the emergence of antibiotic-resistant bacteria in these animals. “These resistant bacteria can contaminate the foods that come from those animals, and persons who consume these foods can develop antibiotic- resistant infections,” the CDC states in a paper titled “Antibiotic Resistance From the Farm to the Table.” The U.S. Food and Drug Administration regulates antibiotics intended for use in humans or in animals. In food-producing animals, FDA-approved uses of antibiotics include disease treatment for animals that are sick; disease control for a group of animals when some of the animals are sick; and disease prevention for a group of healthy animals that are at risk of becoming sick. Growth promotion or increased feed efficiency in a herd or flock of animals to promote weight gain had been allowed but is being phased out under an agreement announced with drug manufacturers June 30. Veterinarian oversight of remaining therapeutic uses will be phased in by the end of 2016. “We are quite hopeful about the new VFD process, which will bring medically important antimicrobials in feed under veterinary oversight—much like a prescription for medicated feed,” Hoang said. FDA reports that some drug sponsors have already begun to implement the changes. While Duran appreciates the caution being taken and believes that antibiotics are overused in pet and human prescriptions, she’s concerned about an overreaction to the use of antibiotics in food-producing animals. “One of the reasons America has stayed strong and great is because we have the cheapest food around,” Duran said, noting that in many nations people spend 40 percent or more of their incomes on food. Too many restrictions on the nation’s agricultural producers could hurt the ability to deliver food affordably to Americans, and Duran believes there are enough regulations in place to ensure the problem of antibiotic resistance doesn’t explode. “People have a perception that people are eating antibiotics in their meat, but they are not,” Duran said. “We have really safe food.” AVMA’s judicious-use principles for antibiotics The American Veterinary Medical Association’s judicious-use principles for antibiotics: Disease prevention strategies like appropriate husbandry and hygiene, routine health monitoring and vaccination should be included as part of a comprehensive animal/herd health plan. Once disease has occurred, other management and intervention strategies may be considered prior to antimicrobial treatment. Judicious use of all antimicrobials should include appropriate veterinary oversight. Extralabel use of antimicrobials must meet all the requirements of the veterinarian-client-patient relationship as defined in the Animal Medicinal Drug Use Clarification Act amendments to the Federal Food, Drug, and Cosmetic Act and its regulations. Extralabel use in food animals necessitates an extralabel withdrawal interval to be assigned by the attending veterinarian on the basis of information on the species, dose, route and frequency of treatment in conjunction with available scientific pharmacokinetic data. Antimicrobials requiring a prescription must be used only under the order of a licensed veterinarian. A veterinary feed directive must be issued only by a licensed veterinarian in the course of the veterinarian’s professional practice. Accurate records of treatment and outcome should be maintained. Antimicrobials should be used in animals only after careful review. Use narrow-spectrum antimicrobials whenever appropriate. Use microbial culture and antimicrobial susceptibility results to aid in the selection of antimicrobials when clinically relevant. Regimens for antimicrobial treatment, control or prevention of disease should be based upon current scientific and clinical principles. Antimicrobial use should be confined to appropriate clinical indications. Inappropriate uses such as for uncomplicated viral infections should be avoided. To minimize selective pressure, therapeutic exposure to antimicrobials should be minimized by treating only for as long as needed for the desired clinical response. Limit therapeutic antimicrobial treatment to ill or at-risk animals, treating the fewest animals indicated. Minimize environmental contamination with antimicrobials whenever possible.
