DVM, Dipl. ACPV
College of Veterinary Medicine
North Carolina State University
Raleigh, North Carolina U.S.A.
The principles of judicious therapeutic antimicrobial were developed for producers to be familiar with the use of therapeutic antimicrobials (antibiotics) in order to maximize therapeutic efficacy while minimizing the development of resistance. Antibiotic resistance is a global problem that affects both humans and animals. The development of resistance is a consequence of the use of antimicrobials. Concerns about the use of antibiotics in food producing animals involve food safety issues because meat products from animals have been identified as transfer vehicles for food borne illness in humans. It is imperative that everyone involved in food animal production, veterinarians and producers, as well all human health care providers work together in minimizing the development of antibiotic resistance. All producers involved in poultry production should familiarize themselves with these principles of judicious therapeutic use of antibiotics to insure that a cooperative effort is established by the producer and veterinarian in the control and treatment of bacterial diseases of poultry.
The following principles of judicious therapeutic antibiotic use should be considered by producers to maximize the benefits of therapeutic antibiotic use while minimizing the development of resistance.
Preventive strategies, such as appropriate husbandry and hygiene, routine health monitoring, and immunization, should be emphasized
The foundation of the success in the poultry industry is through effective management and therapeutic practices that prevent disease. The foundation of biosecurity (preventative disease management) starts with the producer. Farms utilizing all-in-all-out production minimize the presence of multiple ages of flocks on farms to help in disease prevention. Biosecurity programs on poultry farms should be in place to help prevent the introduction of diseases. The use of coveralls, boots and head coverings prevents the introduction and spread of disease within and between farms. Producers should also work with veterinarians and health specialists to establish sound preventative disease prevention programs based on vaccination strategies to reduce disease outbreaks in poultry. The poultry industry is the leader in novel vaccination procedures for vaccination of large numbers of poultry. Breeder and meat production flocks should be monitored for protective response to vaccinations. Serological monitoring of disease exposure forms the basis of strategic vaccination programs. An effective way of minimizing antibiotic resistance is to avoid antibiotic use through the effective prevention of disease exposure and/or vaccination to achieve protection against disease outbreaks.
Other therapeutic options should be considered prior to antibiotic therapy
Poultry producers should approach the treatment of diseases with antibiotics very seriously. Because of the cost of disease treatment with antibiotics, therapeutic antibiotic intervention should be used only as a tool to treat active disease. Management adjustments should be made when disease outbreaks occur by reacting to environmental temperature, ventilation, and litter moisture to minimize the impact of any disease condition in flocks. Supportive therapy with vitamins and electrolytes may be utilized in some cases of disease outbreaks to help avoid the use of antibiotics. All management and non-antibiotic intervention strategies should be explored and a veterinarian or health specialist consulted prior to the use of antibiotics.
Judicious use of antibiotics, when under the direction of a veterinarian, should meet all requirements of a valid veterinarian-client-patient relationship
A valid veterinarian-client-patient relationship (VCPR) should be established at any time prescription antibiotics are used or any antibiotic is used not in accordance to labeled directions. The VCPR must be established and followed in all flocks prior to antibiotic therapy. It is against federal law to use prescription antibiotics or antibiotics in an extra label manner without an established valid VCPR. A valid VCPR means that certain conditions are met prior to the initiation of treatment.
- A veterinarian must be involved. The veterinarian assumes responsibilities in making a clinical judgment and/or diagnosis in the flock. He/she is knowledgeable about the health status of the flock. The producer agrees to follow the directions of veterinarian;
- The veterinarian has sufficient knowledge of the flock, has recently seen the flock, and is knowledgeable with regards to the management of the flock;
- The veterinarian is available for consultation and follow-up evaluation of the antibiotic treatment.
Poultry producers in integrated poultry companies should consult the company veterinarian prior to the initiation of any antibiotic treatment. Veterinarians should closely monitor antibiotic use in their poultry flocks. They maintain close contact with service technicians and managers related to the use of antibiotics. Antibiotics should always be used under the direction and knowledge of the company veterinarian or veterinary consultant.
Prescription, Veterinary Feed Directive, and extralabel use of antibiotics must meet all the requirements of a valid veterinarian-client-patient relationship
At the present time, no feed additives are approved for prescription or by veterinary feed directive in poultry. If these products are approved in the future, strict compliance with regulations should be followed with the same policies set for other antibiotic use.
Extralabel antibiotic therapy must be prescribed only in accordance with the Food, Drug, and Cosmetic Act and its regulations
In 1996, the Animal Medicinal Drug Use Clarification Act (AMDUCA) amendments to the Food, Drug and Cosmetic Act and its regulation became federal law. This essentially legalized extra label antibiotic use by veterinarians (not for producers). It defined the valid VCPR as discussed previously. Veterinarians in integrated poultry companies strive to use antibiotics at labeled indications and dosage. When prescribing extralabel use of antibiotics, a veterinarian performs it only in compliance with AMDUCA.
Veterinarians should work with those responsible for the care of poultry to use antibiotics judiciously regardless of the distribution system through which the antibiotic was obtained
Poultry producers are responsible for the production of poultry on their farms; however, information provided by live production mangers, veterinarians and/or best management practices that have been established by the National Chicken Council and National Turkey Federation should be followed. Veterinarians should work closely with producers, service technicians, service persons, and production managers to insure responsible use of therapeutic antibiotics. A veterinarian, however, should always be responsible for the initiation and evaluation of antibiotic therapy.
Regimens for therapeutic antibiotic use should be optimized using current pharmacological information and principles
Continuing education programs by the American Veterinary Medical Association, American Association of Avian Pathologists and technical updates from pharmaceutical technical service veterinarians, keep poultry veterinarians and managers up to date on current information regarding antibiotic use. Producers should use these individuals as resources regarding current information on antibiotic use.
Antibiotics considered important in treating refractory infections in human or veterinary medicine should be used in animals only after careful review and reasonable justification. Consider using other antibiotics for initial therapy
Poultry veterinarians and producers should recognize the importance of antibiotic resistance in both human and veterinary medicine. Important antibiotics used in both poultry and humans are to be held in reserve to minimize the rate of resistance development to these important compounds.
Use narrow spectrum antibiotics whenever appropriate
Antibiotics usually are either broad or narrow in their spectrum of activity. A broad-spectrum antibiotic tends to be active against a broader range of bacteria including both gram negative and gram positive organisms (i.e. bacteria that causes colibacillosis, cholera, etc) while narrow spectrum antibiotics are active against either gram positive (for example Staphylococcus) or gram negative (for example E. coli). Broad-spectrum antibiotics tend to lead to the development of resistance in bacteria that are not the ones involved in the infection you are treating. To minimize the development of broad-spectrum resistance, narrow spectrum, bactericidal antibiotics should be chosen when culture and sensitivity results suggest therapeutic success. Veterinarians will advise the producer in the use of the appropriate antibiotics.
Utilize culture and susceptibility results to aid in the selection of antibiotics when clinically relevant
Before antibiotic therapy is initiated, based on mortality and morbidity, typically affected birds should humanely euthanized and samples taken for bacterial culture and sensitivity. This can be performed at regional State diagnostic laboratories, Universities or in integrated companies diagnostic facilities. This is common practice in the poultry industry today. A poultry veterinarian uses this information to make informed decisions regarding the appropriate antibiotic therapy to be initiated. This information should be kept by the producer and veterinarian as part of the flock and farm history to determine changes in antibiotic susceptibility patterns on farms.
Therapeutic antibiotic use should be confined to appropriate clinical indications. Inappropriate uses such as for uncomplicated viral infections should be avoided
Viral, fungal and other non-bacterial infections should not be treated with antibiotics. Producers and veterinarians should pay special attention to disease outbreaks to determine if, and when antibiotics therapy is warranted. Every effort should be made to address disease outbreaks with other disease management strategies prior to the initiation of antibiotic therapy.
Therapeutic exposure to antibiotics should be minimized by treating only for as long as needed for the desired clinical response
Due to the cost of antibiotic use in poultry and limited availability of antibiotics in poultry, producers should work with veterinarians and service technicians to closely monitor antibiotic treatments and minimize antibiotic therapeutic exposure in flocks. Producers should use antibiotics according to labeled indications that include the treatment period. Any extra label use of antibiotics should be in accordance with a VCPR and within AMDUCA regulations. Producers should avoid prolonged use of antibiotics.
Limit therapeutic antibiotic treatment to ill or at risk animals, treating the fewest animals indicated
In a poultry disease outbreak, all birds are not infected at the same time with the disease to which antibiotic therapy is warranted. However, birds in the same house are "at risk" to the same primary disease that results in secondary bacterial infections. Only birds within the same house that are ill or at risk should be treated. Producers should not treat adjacent houses that are not clinically affected with disease. If therapeutic antibiotic intervention isn't cost effective and a low number of birds are infected per house, the cost of treatment will usually dictate that no antibiotics be used at all.
Minimize environmental contamination with antibiotics whenever possible
Every effort should be made to avoid environmental contamination with antibiotics. The cost of antibiotics generally ensures that the antibiotics be used specifically in the diseased flock and not introduced into the environment unnecessarily.
Accurate records of treatment and outcome should be used to evaluate therapeutic regimens
Record keeping is an integral part of the integrated poultry industry. Production records including medication costs, evaluation and outcome are kept and placed in the history of the farm for future reference in determining any changing antibiotic susceptibility patterns. Producers should also maintain their own records of flock treatments (product used, date of use, duration of treatment, dosage, outcome of treatment, etc.) for future reference.
The overall goals of judicious therapeutic antibiotic use and the principles explained in the publication are:
- To provide information to producers regarding the appropriate use of antibiotics in poultry;
- Minimize antibiotic resistance development;
- Provide insight and bring awareness to producers of the global problem of antimicrobial resistance.
The producer and veterinarian should work closely when antibiotic therapy is needed in a flock and both should continue to work toward ensuring a safe food supply for consumers. These above mentioned principles are used commonly in today's industry, and under today's production standards.
Challenges for the Turkey Industry
A major challenge for the turkey industry is the continued use of currently approved antimicrobials. The above statement is not to put fear in producers that use antimicrobials. It is a fact, and however, that the actions the food animal industries take are currently scrutinized by numerous individuals, consumer groups, and anti animal agriculture groups. Preventative disease management will be crucial in the future if our current antimicrobial arsenal is reduced any further.
One of the most significant activities by the Center for Veterinary Medicine, Food and Drug Administration (FDA-CVM) has been the draft of a Draft Guidance Document for Industry #152, Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to Their Microbiological Effects on Bacteria of Human Health Concern. This represents the thinking of FDA-CVM on how it intends to evaluate, approve and/or remove from the market, antimicrobials that are used in food animals. This thinking, however, was first introduced by the introduction of the Framework Document (Proposed Framework for Evaluating and Assuring the Human Safety of the Microbial Effects of Antimicrobial New Animal Drugs Intended for Use in Food-Producing Animals), in January 1999. Numerous public meetings regarding the Framework Document have been held to provide input on the document. For example, a public meeting was also been held on October 2002 to provide comments regarding Draft Guidance #152. Written comments were accepted until November 27, 2002. The National Turkey Federation and other stakeholders provided input at the public meeting held in October.
In both the Framework document and Draft Guidance #152, an important component is the categorization (ranking) of drugs used in food animals based on their importance in human medicine. Drug classification was to be categorized as high, medium, and low depending on their importance in human medicine. The Center for Drug Evaluation and Research (CDER) was asked to provide their input on drug categorization. Basically except for bacitracin (low) and tetracyclines (medium), all antimicrobials were considered in the high category by CDER.
The importance of the ranking of antimicrobials is paramount for the future of antimicrobial approvals and for the disposition of currently approved antimicrobials. Antimicrobials listed as high will not be available for approval for use in food animals and those of medium will likely have severe restrictions. The original Framework Document stated that both future approvals and currently approved antimicrobials could be impacted. There were numerous comments that stated that the ranking should be based on those antimicrobials, bacteria or resistance determinants that are food borne.
Guidance Document #152 identifies a qualitative antimicrobial resistance risk assessment approach in determining which antimicrobials would result in a high risk for human illness caused by; specific antimicrobial-resistant bacteria, attributable to a specified animal-derived food commodity, and is treated with the human antimicrobial drug of interest. In this risk assessment approach, it does not take into consideration further processing or value added product exposure in humans. The assumption is made that all meat commodities are provided to the consumer in the raw form. It also appears, from this author's perspective, that herd and flock based treatments are negatively impacted due to exposure of antimicrobials to large numbers of ill and at risk animals.
Legislative activity that could also impact the poultry and other food animal industries is the Preservation of Antibiotics for Human Treatment Act of 2002 (HR 3804). This legislation was introduced by Sherrod Brown and basically calls for the banning of sub-therapeutic use of certain classes of antimicrobials in food animals. These include: penicillins, tetracyclines, macrolides including, but not limited to, erythromycin and tylosin, lincomycin, bacitracin, virginiamycin, aminoglycosides, and sulfonamides.
Summary
In conclusion, the principles of judicious therapeutic antimicrobial discussed are important to all of us involved in the health of poultry. We must do our part to use our limited therapeutic agents wisely and understand the impact we may have on their future use.
Unfortunately, there are those outside of our industry that are using everything at their disposal to limit, if not eliminate, the use of many of our antibiotics.
We need to live by example, and re-enforce the concept that antimicrobial resistance in humans should not be laid on the doorstep of animal agriculture.
From Proceedings of the "Midwest Poultry Federation Convention", St. Paul, Minnesota, U.S.A.
