Enterococcus cecorum causes locomotor disorders and generalized infections (sepsis) in broiler farms, particularly those with rapid growth. It is increasingly problematic, its incidence having multiplied by 100 in 15 years.
Enterococcus cecorum is naturally present in the digestive system of poultry, and despite evidence showing the existence of strains with pathogenic potential, these clinical isolates remain little known. It is with the aim of better characterizing them that researchers from INRAE and ANSES have teamed up.
Decipher your DNA
INRAE and ANSES scientists conducted a first study on theanalysis of genetic diversity d’Enterococcus cecorum circulating in French farms. For this, they studied a hundred isolated samples of sick animals. The bacterial strains that cause the disease are called clinical variants, those that come from animals without symptoms are called non-clinical variants. From there, a comparative analysis of their genomes made it possible to establish the complete panoply of genes and the list of those common to all the variants.
Result : the clinical variants followed a distinct course non-clinical variants. Their evolutionary group brings together the majority of variants responsible for infections in France, but also in other European countries and in the United States.
With a view to monitoring farms, scientists have identified six genes that make it possible to determine the evolutionary origin of a variant in 94% of cases. Additionally, they also have identified antibiotic resistance genesto better target possible treatments.
Assess antibiotic resistance profiles
At this stage, our researchers had identified resistance genes of the clinical variants, but what about the non-clinical ones?
In their second study, they tested the effect of antimicrobial molecules on a collection of over 200 variants. Their objective ? Develop an analysis method and determine antibiotic limit concentrations or epidemiological thresholds, making it possible to identify antibiotic-resistant variants.
These thresholds were determined for 29 antimicrobial molecules. These works show that many variants are resistant to antibiotics used in breeding. But this resistance does not concern the antibiotics used in human medicine.
These two complementary studies show the evolution of this bacterium whose populations now include a group of infectious variants. All the results provide insight into its genetic diversity and resistance to antibiotics. They will help to better prevent and control diseases related to Enterococcus cecorum.