Invasive Streptococcus suis isolated in Spain contain a highly promiscuous and dynamic resistome

Area of Science:

• Veterinary Microbiology
• Antimicrobial Resistance
• One Health

Background:

• Streptococcus suis is a significant pathogen affecting both swine and human health.
• Understanding antimicrobial resistance (AMR) patterns in S. suis is crucial for public and animal health.
• Surveillance of AMR in S. suis is essential, particularly in regions with intensive pig farming.

Purpose of the Study:

• To determine the rates of AMR in invasive S. suis isolates in Spain from 2016 to 2021.
• To investigate the genetic origins and mechanisms of AMR in these isolates.
• To assess the potential for AMR dissemination between animal and human pathogens.

Main Methods:

• Antibiotic susceptibility testing was performed on 116 S. suis isolates against 18 antibiotics.
• Statistical analysis was used to associate AMR with isolate genotypes and origins.
• Whole genome sequencing and PCR screening identified antimicrobial resistance genes and mutations.

Main Results:

• High AMR rates (>80%) were observed for tetracyclines, spectinomycin, lincosamides, and marbofloxacin.
• Multidrug resistance was prevalent, found in 90% of isolates.
• 23 AMR genes were identified, including 4 novel ones, with several located on mobile genetic elements. Mutations in target genes also contributed to resistance.

Conclusions:

• S. suis plays a significant role in the dissemination of AMR among veterinary and human pathogens.
• Control of AMR in S. suis requires a One Health approach, integrating animal and human health strategies.
• Effective AMR management in S. suis is vital for regions with high pig production to mitigate public health risks.