02.10.2015

Antimicrobial resistance is an emerging problem worldwide. It reduces the effectiveness of antimicrobial treatment of infectious diseases in humans and animals thereby leading to increased morbidity and mortality, as well as higher costs. It is well established that there is a strong association between the usage of antimicrobial agents and the occurrence of resistance. The selective pressure exerted following use of antimicrobial agents is a key issue in the epidemiology of resistance. Moreover, resistance can be disseminated through the spread of resistant pathogenic bacteria themselves or by horizontal transfer of resistance genes from one type of bacteria to another Such transfer is not limited to closely related bacteria; it can also take place between bacteria of different evolutionary origins and/or ecological niches. Thus, antimicrobial drug usage and resistance in one ecological compartment can have consequences for the occurrence of resistance in another compartment. When addressing antimicrobial resistance – the occurrences, causes, consequences and preventive measures – a holistic approach is needed, encompassing both data on usage and resistance in human and veterinary medicine, as well as microbes in food production.
Usage of antimicrobial agents in animals The usage of antimicrobial veterinary medicinal products (VMPs) for therapeutic use in food producing animals in Norway is low. In 2014, the total sales of antimicrobial VMPs for terrestrial animals were 5,927 kg. The annual sales, in kg active substance, of antimicrobial VMPs approved for use in terrestrial animals decreased by approximately 38% from 1995 to 2014. The reduction in use is solely accounted for by a reduction in the use in food producing animals (41% reduction) while for antimicrobial VMPs marketed for companion animals an increase of 19% in the sales is observed. The sales patterns of antimicrobial VMPs for terrestrial food producing animals have gradually become more favourable as the proportion of penicillin use has increased; the proportion accounted for by pure penicillin preparations rosegradually from 25% of total sales in 1995 to 53% in 2014.
In this period the sales of aminoglycosides decreased from 27% to 10% of total sales; this is due to a reduction in the use of combination preparations of penicillin and dihydrostreptomycin in food producing animals. The reduced
sales of antimicrobial VMPs in terrestrial animals as well as the favourable prescribing patterns are mainly explained by a campaign on prudent use of antimicrobials conducted by the Norwegian husbandry organisations and the Norwegian Medicine Authority during the second part of the 1990s. Furthermore, a target set by the Norwegian husbandry organisations to reduce the sales by 25% with 1995 as the reference year is thought to have had a major impact on this decrease.
In 2014, the total sales of ionophore coccidiostat feed additives, in kilograms of active substance, were more than four times the amounts used prior to the withdrawal of antimicrobial growth promoters in 1995. This is explained by increased production of broilers. While monensin was the most frequently used ionophore in poultry in 1995, the usage of coccidiostats has since then been dominated by narasin.
Antimicrobial resistance is still a limited problem among clinically important microbes in Norway. The relatively
low usage of antimicrobial agents as well as appropriate patterns of use must be maintained to preserve this rather
favourable situation. The data presented in this report show that Norwegian antimicrobial policies in food
production and health care have been succ