A survey of group-level antibiotic prescriptions in pig production in France

There is world-wide concern that antimicrobial use in food-producing animals might contribute to antimicrobial resistance both in animals and in humans. The relationship between antimicrobial use and resistance is likely to be related to frequency of prescription of the compound, dose and duration of treatment. Routine collection of that information is not possible today in France. A postal survey of French pig veterinarians therefore was carried out in October 2000. The questionnaire focused on the last antibiotic group-level prescription made; data were collected on the type of animals, presumptive clinical diagnosis and drug prescription. The list frame was defined using a veterinary yearbook. All practitioners with mention of pig in the treated species or with employment in intensive animal production were sent the questionnaire. Out of the 431 selected practitioners, 303 responded to the self-administered questionnaire (overall return proportion 70%). 159 prescriptions were received and analysed (response proportion 37%). Their repartitions according to indications and active compounds were summarised. Mean prescribed daily doses and mean treatment length were calculated for four antibiotics: amoxicillin, colistin, oxytetracycline, tylosin. Prescribed daily dose were in the range of dosages used and recommended in Europe. High variations were encountered in treatment length: from 3 to 21 days.

Antibacterial drugs prescribed for dogs and cats in Sweden and Norway 1990-1998

The usage of veterinary antibacterial drugs in dogs and cats in Sweden and Norway for the period 1990-1998 was investigated by use of drug wholesalers' statistics. Additionally, usage of human antibacterial drugs in these species in Sweden was investigated by use of prescription data for the period 1996-1998. On average, more than 50% of the prescribed veterinary antibacterials in Sweden were beta-lactam antibiotics. In Norway, about 75% of the preparations prescribed for dogs and cats contained sulfonamides and trimethoprim. Furthermore, the prescription data from Sweden showed a reduced usage of human antibacterials prescribed for dogs and cats since the beginning of the 1980s. Approximately 20% of the prescribed packages for dogs in the years 1996-1998 were human approved drugs. The corresponding figure for cats was 13%. The differences between the countries in the choice of antibacterial drugs can be explained by differences in the availability of approved preparations during the study period. The consumption of veterinary antibacterials in dogs and cats in Sweden during the period was in the range of 3% to 8% of the total use of veterinary antibacterials. The corresponding figures in Norway were in the range of 3% to 7%. It is of vital importance to study usage patterns of antibacterial drugs in dogs and cats in surveillance and control of bacterial resistance, but also in discussions of therapeutic appropriateness. Therefore, further research is needed in this area.

The usage of veterinary antibacterial drugs for mastitis in cattle in Norway and Sweden during 1990-1997

The prescribing patterns and annual incidence of use of antibacterial drugs for the treatment of mastitis in cattle in Norway and Sweden during the period 1990-1997 were estimated from drug wholesaler statistics. Although the drugs included in this study are also used in other species and/or other indications, mastitis in cattle is by far the most-common indication for their use. We used these sales figures to evaluate trends in the use of antibacterial drugs and changes in the incidence of treatment in bovine mastitis in Norway and Sweden. To facilitate comparisons (correcting for differences in activity and dosage) between the relative proportions of antibacterial drugs used in bovine mastitis, we introduced defined daily dose cow (DDDcow) as unit of measurement. Tentative DDDcow for the various injectable drugs were derived from doses recommended in Norway and Sweden. For intramammary drugs administered in the form of single-dose applicators, one applicator was defined as the DDDcow. The prescribing patterns of antibacterial drugs in bovine mastitis in Norway and Sweden during the study period seemed to be influenced by treatment policies, substances and formulations approved and treatment cost; length of the withdrawal period also seemed to play a role.

Comparison in prescribing patterns of antibacterial drugs in salmonid farming in Norway during the periods 1980-1988 and 1989-1994

The choice of antibacterial drugs for the treatment of bacterial diseases in farmed salmonids changed dramatically during the period 1980-1994. In terms of treatment doses, oxytetracycline chloride was the most frequently prescribed antibacterial drug during the periods 1980-1983 and 1985-1986. In 1984, prescriptions changed in favour of furazolidone and trimethoprim/ sulphadiazine (1:5). Oxolinic acid was introduced for use in farmed fish in Norway in 1987, and immediately became the drug of choice, comprising 36% and 50% of the prescribed treatment doses in 1987 and 1988, respectively. In 1989, flumequine was temporarily approved for use in farmed salmonids, and during the period 1989-1994 antibacterial drug therapy in farmed salmonids acquired the character of "mono-therapy' with the quinolones flumequine and oxolinic acid. This rapid change-over in the choice of drug may partly be explained by the development of bacterial drug resistance in farmed salmonids, both to oxytetracycline and trimethoprim/sulphadiazine. The prescribing of furazolidone declined to zero during the study period. The morbidity caused by bacterial infections was defined as the number of treatment doses of antibacterial drugs per kg biomass of farmed salmonids per year. It was estimated that during the period 1988-1995, an average of 39% (mean value) of farmed salmon received, in theory, an antibacterial cure once each year. In comparison, the corresponding figure for the period 1981-1988 was 60%. However, in 1993 this figure fell to 13%, and declined even further in 1994 to 2.3%. The practice of on-farm mixing of medicated feed, using prescribed raw materials (pure drug substances) or premix formulations, declined significantly during the period 1992-1994. This was due to the introduction, in 1992, of new regulations on the prescribing of drugs to farmed fish.