Guidelines for prudent use of antimicrobials and their implications on antibiotic usage in veterinary medicine.

Antibiotics are still deemed necessary for the treatment and prevention of infectious diseases in farm animals intended for food production and to protect public health from food-borne diseases. All antibiotics used in veterinary medicine are the same or closely related to antibacterials used in human medicine or may induce cross-resistance. Consumption figures of antibiotics in the European Union (EU) indicate an about 10-fold higher number of treatment days in human medicine when compared to veterinary usage with tetracyclines being the most frequently used group. However, the conditions of antibiotic use in farm animals, mainly in swine and poultry by oral treatment of a large number of animals for prolonged periods of time and risk of underdosing might favour the selection of bacterial resistance. In order to reduce the use of antibiotics and thus to minimize the development of resistance in veterinary medicine, compulsory guidelines for prudent use of antibacterials in animals were published in Germany in December 2000. These guidelines describe the minimum requirements to be followed by veterinarians when administering antibiotics to animals. Key elements of the guidelines are the use of antibiotics on the basis of an exact (preferentially microbiological) diagnosis, choice of the most suitable antibacterial substance (antibacterial spectrum as narrow as possible, margin of safety as high as possible, good tissue penetration if necessary), restricted use of antibiotics with last resort character, adherence to the label instructions (no underdosing or prolongation of dosing interval). Any deviations from the guideline recommendations must be justified and recorded. Results of monitoring of antibiotic usage as medicated feeding stuffs in pig production in the German state Sachsen-Anhalt from October 2000 until March 2002 indicate a change of the prescribing attitude of veterinarians after implementation of the guidelines. The consumption of antibiotics continuously declined from 4255 kg before the guidelines to 1145 kg in the first quarter of 2002 resulting in a reduction of the treatment days per animal from 31.6 (third quarter 2000) to 13.6 days (first quarter 2002). Simultaneously the use of chlortetracycline decreased from initially 76% of the total amount of antibiotics prescribed to 14.7% at the end of the study, respectively. These results suggest an acceptance of the guidelines for prudent antibiotic use by veterinarians as an important tool to reduce the usage of antibiotics and the consecutive development of resistance.