Antimicrobial resistance patterns in Streptococcus dysgalactiae in a One Health perspective

Area of Science:

• Microbiology
• Genomics
• One Health

Background:

• Streptococcus dysgalactiae (SD) is a significant pathogen in both humans and animals.
• Rising antibiotic resistance in SD necessitates investigation into its dissemination across species.
• The One Health perspective is crucial for understanding zoonotic transmission and resistance exchange.

Purpose of the Study:

• To explore zoonotic transmission of SD between humans and animals.
• To investigate the potential for exchange of antibiotic resistance traits between SD from different host populations.
• To analyze antimicrobial susceptibility and genomic data of SD isolates from diverse hosts.

Main Methods:

• Whole genome sequencing and phenotypical antimicrobial susceptibility testing were performed on 407 SD isolates.
• Isolates included human bloodstream infections (n=274) and animal infections (n=133) from Norway (2018-2019).
• Phylogenetic analysis was used to delineate host-associated genotypic resistomes.

Main Results:

• Antimicrobial resistance genes were detected in 26% of human, 25% of companion animal, and 2% of livestock isolates.
• Distinct host-associated genotypic resistomes were observed, with different resistance genes for erythromycin (erm(A) in humans vs. erm(B)/lsa(C) in animals).
• The tetracycline resistance gene tet(O) was found on different mobile genetic elements in human and animal SD, with rare instances of near-identical mobile elements across hosts.

Conclusions:

• SD strains show phylogenetic delineation aligned with host adaptation and niche specialization.
• Direct transmission of SD strains or resistance genes between different ecological niches appears infrequent in Norway.
• While host specialization is evident, the potential for rare exchange of resistance elements warrants continued surveillance.