Antimicrobials for veterinary use: lower levels of use and resistance are confirmed, but efforts must continue

Antimicrobial resistance is a major public health issue, for both human and veterinary medicine. In France, many measures have been taken to promote the rational use of antimicrobials. For instance, in 1999, the French Agency for Veterinary Medicinal Products (ANSES-ANMV) began monitoring sales of veterinary antimicrobials. Today, as part of its half-day devoted to antimicrobial resistance in animal health, ANSES is publishing the annual report on sales of veterinary antimicrobials in France in 2013, and the 2013 report of the French surveillance Network for Antimicrobial Resistance in Pathogenic Bacteria of Animal Origin (RESAPATH) coordinated by its Lyon and Ploufragan laboratories. For the first time, the level of exposure to antimicrobials was lower than that of 1999, while at the same time, a decline in resistance to critical antimicrobials in most animal production sectors is to be noted. However, efforts must continue, and in particular, increases in the use of critical antimicrobials in certain animal species, especially domestic carnivores (dogs and cats) should be monitored closely. It also seems necessary to obtain more precise data on the use of antimicrobials by species and animal category.

Sales of antimicrobials in 2013: the lowest level of exposure since 1999

In 2013, the total volume of sales of antimicrobials amounted to 699 tonnes. All animal species combined, the level of animal exposure to antimicrobials was for the first time lower than that of 1999, the year the monitoring plan was launched (-5.5%). Overall exposure in 2013 also fell by 7.3% compared to 2012 and has decreased by 15.7% over the last five years.

However, this overall trend must be qualified according to the target species and classes of compounds. Thus, although between 2012 and 2013 exposure to antimicrobials decreased by 6.6% for cattle, 5.4% for poultry, 4% for pigs and 1.7% for domestic carnivores, it rose by 3.6% for rabbits.

Over the last five years, oral exposure has fallen by 24.3% while there has been an increase of 9.4% for injections. This decrease in oral exposure is mainly due to a decline in the use of medicated premixes (-45.9% over 5 years, and -15.4% in 2013 compared to 2012). These changes probably reflect a decrease in the use of antimicrobials for prevention.

Exposure of animals to critical antimicrobials (third- and fourth-generation cephalosporins and fluoroquinolones) has stabilised over the past few years. In 2013, for all animal species combined, a significant fall was observed in the use of cephalosporins (-9.8% compared to 2012) and a smaller fall in fluoroquinolones (-1.5%). Nevertheless, increases observed in certain animal species, especially domestic carnivores (mainly dogs and cats), in which exposure to cephalosporins rose by 25% between 2012 and 2013, and exposure to fluoroquinolones by 12.2%, should be monitored closely.

Moreover, the reductions observed are greater in the animal sectors where specific measures have been introduced. Thus, following the initiative in the pig sector to voluntarily restrict the use of newer-generation cephalosporins, exposure of pigs to this class fell by 66% between 2010 and 2013.

It should be remembered that in its Opinion published in June 2014, on the risk of emergence of antimicrobial resistance associated with patterns of antimicrobial use, ANSES repeated its recommendation to reserve the use of newer-generation cephalosporins and fluoroquinolones as a last resort for specific situations that need to be identified for each sector and strictly regulated.

Antimicrobial resistance: an overall downward trend in rates of resistance since 2006

By collecting antibiogram data on pathogenic bacteria of animal origin isolated in sick animals, the RESAPATH network helps to monitor trends in resistance to antimicrobials in pathogenic animal bacteria, detect the emergence of certain diseases and characterise their molecular mechanisms.

The network's scope increased further in 2013 (it has grown continually since 2005). It now has 67 member laboratories (as opposed to 64 in 2012). It collected 33,428 antibiograms (31,211 in 2012) thanks to wider coverage of pets.

Decreases in resistance to critical antimicrobials (third- and fourth-generation cephalosporins and fluoroquinolones) are again to be noted this year. This trend is not the same for every sector, nor for every antimicrobial, but major positive results have nevertheless been achieved.

Lastly, multi-resistance is considered to be resistance to at least three different classes of antimicrobials. It is common with regard to E. coli, especially in cattle (23.4%), pigs (16.9%), horses and dogs (both at 10.5%). On the other hand, this phenomenon is less pronounced in hens and chickens (6.2%) and in turkeys (3.4%).

New objectives and initiatives under way to obtain more precise data 

Given these different results, the Agency considers it necessary to obtain more accurate data on the use of antimicrobials by species and category of animals, a need that is regularly reiterated at European level. Therefore, in its assessment of the risk of emergence of antimicrobial resistance associated with patterns of antimicrobial use, published in June, it recommended the introduction of long-term tools for monitoring more closely the administration of antimicrobials on farms. In addition, initiatives are under way to better estimate exposure to antimicrobials by animal category and physiological stage. The measures in the national plan to reduce the risks of antimicrobial resistance in veterinary medicine, which include conducting surveys by sector, will provide some answers in the near future that will improve the documenting of actual use in the production sectors. Results have already been obtained this year in the cattle and fish farming sectors, and these were discussed during the course of the half-day devoted to antimicrobial resistance in animal health.

The decline in exposure to antimicrobials observed in recent years, both overall and by species, seems to confirm the positive impact of the various measures taken regarding the rational use of antimicrobials. In two years, a 12.7% reduction has been observed, which is currently in line with the EcoAntibio 2017 target to reduce use by 25% in five years, even though efforts still need to be made to reach this ambitious objective.