Sunday, 1 February 2015

Antimicrobials use and antimicrobial resistance in humans and food-producing animals

EFSA, EMA and ECDC have published a joint report on the correlation of the consumption of antimicrobials by food-producing animals and humans and the occurrence of antimicrobial resistance. Not surprisingly, they found positive associations between antimicrobial consumption and antimicrobial resistance in humans and food-producing animals but also, in some cases, positive associations between antimicrobial consumption by food-producing animals and resistance to antimicrobial agents exhibited by bacteria in humans.
'Mycobacterium tuberculosis bacteria'
by NIAID under a CC license

Antimicrobial resistance is a topic that I re-visit from time-to-time. In brief, antimicrobial resistance is the phenomenon where a bacterium acquires resistance towards an antimicrobial agent. This may happen via a spontaneous mutation or via gene transfer. The emergence of antimicrobial resistance is a very important issue, regardless of whether the micro-organisms where resistance is developed are, themselves, pathogens or not. Bacteria have the ability for horizontal gene transfer. Thus, once the genes responsible for a specific antimicrobial resistance appear in a microbial population, the propagation of the genes to other microbial populations, including different bacteria, will take place at some point. Obviously, this becomes critical when pathogens acquire such genes, especially when taking into consideration that the antimicrobial agents (antibiotics) we have at hand to fight them are finite (and rather few).

The report of the three agencies highlights a problem that has been known for a while but sometimes still tends to be overlooked. There are vastly different practices across countries with regards to the way that antimicrobial agents are used by doctors and veterinarians to tread human and animal diseases, respectively. To make things worse, residues of veterinary medicines in food-producing animals may also remain in the meat at the time of consumption. As you may suspect, bad practices in either of those fields can give further rise to antimicrobial resistance and, in the longer run, can both accelerate the emergence of antimicrobial resistance of human pathogens.

Given the increasing globalisation of livestock production, as well as the increased mobility of people around the globe, it is necessary to boost efforts for better management of the use of antimicrobial agents, both against human and animal diseases.

This is no simple task, though.

Optimum management requires resources and infrastructure that differ a lot from place to place. Think, for instance, that keeping food-producing animals healthy without resorting to the use of antimicrobial agents needs hygiene, animal-housing and health monitoring practices that come at a cost. On top of that, such animals may be less productive in terms of meat. Such effects discourage the adoption of practices featuring responsible use of antimicrobial agents. There, education, as well as legal measures, have a strong role.

In any case, however, the fact that the task in question is difficult that doesn't mean that the effort should halt. At least not until we find other, reasonably effective ways to deal with pathogens.

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