Is blaCTX-M-1 Riding the Same Plasmid Among Horses in Sweden and France?

The research study investigates the prevalence of bla/IncHI1 plasmid combination, a type of antibiotic-resistance gene, in horses in France and Sweden and the potential threat they pose to public health.

Objective of the Research

• The study aimed to understand the epidemiology of bla plasmid in horses in a European context by examining a collection of Escherichia coli samples from sick horses in France and Sweden from 2009 to 2014.

Sample and Methodology

• A total of 74 E. coli samples that produce an extended-spectrum beta-lactamase, a type of antibiotic-resistant enzyme, were studied.
• The genetic relatedness, plasmid content, and molecular features of these samples were analyzed.

Key Findings

• 80% of the E. coli samples from diseased horses carried bla on large IncHI1 plasmids.
• There was a country-wise variation in the plasmid sequence type (pST), with pST2 being more common in Sweden and pST9 in France. However, both countries also showed the existence of IncI1/pST3 plasmids.
• The CTX-M-1-producing E. coli mainly belonged to the clonal complex 10, and to groups ST641 and ST1730.
• Clonal spread of E. coli CTX-M-1 producers was evident in different regions of the same country and over several years.

Implications

• Theibla plasmid genotypes detected were also reported in the Netherlands, pointing to a possible common source of contamination in Europe.
• The spread of IncI1/pST3 plasmids in horses is concerning due to their successful transmission in other animal hosts such as chickens and cows.
• The study proposes that monitoring the evolution and spread of antimicrobial resistance in equine environments is crucial to prevent further propagation of antibiotic-resistance mechanisms, which pose a risk to human and animal health.