More than 20 percent of Escherichia coli isolates taken from horses in France were found in a study to be multidrug resistant.
Food-producing animals were found to have an even higher prevalence, Clémence Bourély and her colleagues reported in the journal Frontiers in Microbiology.
E. coli is the most frequently isolated pathogen in food-producing animals and in pets. It is a major infectious agent for humans, being particularly implicated in urinary tract infections.
E. coli is also considered to be an excellent sentinel of antimicrobial resistance for a wide range of animal species.
For their study, French scientists set out to determine whether E. coli co-resistance to two antibiotics, amoxicillin and tetracycline, was an indicator of multidrug resistance in animal health.
They analyzed E. coli isolates collected between 2012 and 2016 by RESAPATH, the French surveillance network for antimicrobial resistance in diseased animals.
The proportions of multidrug-resistant isolates and those that were co-resistant to amoxicillin and tetracycline were calculated for seven animal species — horse, cattle, dog, swine, poultry, duck, and turkey.
The degree of agreement between these two proportions was then calculated.
In total, 55,904 isolates were analyzed.
Multidrug-resistant proportions were found to be variable among the seven animal species, ranging from 21.9% in horses to 56.0% in cattle.
A similar situation was observed for proportions of isolates with co-resistance to amoxicillin and tetracycline, with the highest value for cattle (65.0%), followed by swine, ducks, and turkeys.
The proportion of isolates with co-resistance to amoxicillin and tetracycline was higher than the proportion of multidrug-resistant isolates for all food-production animals, but lower for companion animals (dog and horses).
These differences, they said, were probably due to variations in antibiotic use among animal species, despite the widespread use of amoxicillin and tetracycline in domestic animals.
This co-resistance was also most often associated with resistance to other antibiotics, regardless of the animal species considered.
There was, they said, substantial agreement between multidrug resistance and co-resistance to amoxicillin and tetracycline for all the species investigated.
“Given the widespread use of penicillin and tetracyclines in animal health, co-resistance to amoxicillin and tetracycline could be an efficient indicator of multi-drug resistance in E. coli isolates,” they concluded.
“This potential indicator is also precise, convenient and suitable for routine use.”
Of the 21,451 E. coli isolates taken from cattle tested, 56% were multidrug-resistant, while 65% were found to be co-resistant to the two antibiotics.
There were 2232 isolates from horses tested, 21.9% of which were multidrug-resistant, while 17.7 were co-resistant to the two antibiotics.
There were 3226 isolates taken from dogs, 23.3% of which were multidrug-resistant, with 20.1% co-resistant.
Swine samples totalled 5932, with 44.9% multidrug-resistant and 46.7% co-resistant.
The highest levels of resistance among the three bird species were found in ducks, with 39.7% of isolates being multi-drug resistant, and 45.3% co-resistant.
Co-resistance to Amoxicillin and Tetracycline as an Indicator of Multidrug Resistance in Escherichia coli Isolates From Animals
Clémence Bourély, Géraldine Cazeau, Nathalie Jarrige, Eric Jouy, Marisa Haenni, Agnese Lupo, Jean-Yves Madec, Agnès Leblond and Emilie Gay.
Front. Microbiol., 09 October 2019 | https://doi.org/10.3389/fmicb.2019.02288