Characterisation of Streptococcus suis isolates from wild boars (Sus scrofa)
Verónica Sánchez del Rey1, José F Fernández-Garayzábal2, Gregorio Mentaberre3
1Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense, 28040 Madrid, Spain.
Veterinary Journal (London, England : 1997)
|April 15, 2014
Summary
Wild boars commonly carry Streptococcus suis, a bacterium with diverse strains. Genetic analysis reveals these S. suis strains are distinct from those typically found in pigs and humans.
Area of Science:
- Veterinary Microbiology
- Zoonotic Disease Research
- Wildlife Epidemiology
Background:
- Wild boars (Sus scrofa) are widespread in the Iberian Peninsula.
- They can act as reservoirs for potentially virulent bacterial pathogens, including Streptococcus suis.
- Understanding the prevalence and genetic characteristics of S. suis in wild boar populations is crucial for assessing potential disease transmission risks.
Purpose of the Study:
- To determine the prevalence of Streptococcus suis in wild boar populations across two major Spanish regions.
- To genetically characterize isolated S. suis strains, focusing on serotypes, virulence factors, and population structure.
- To compare the genetic profiles of S. suis from wild boars with those known to infect domestic animals and humans.
Main Methods:
- Bacteriological isolation and serotyping of Streptococcus suis from wild boar samples.
- Genotyping for specific virulence-associated genes (mrp, epf, sly).
- Pulsed-field gel electrophoresis (PFGE) for strain typing.
- Multilocus sequence typing (MLST) to determine population genetics and clonal complexes.
Main Results:
- Streptococcus suis was isolated from 39.1% of examined wild boars.
- Serotype 9 was the most prevalent (12.5%), followed by serotype 1 (2.5%); serotype 2 was rare (0.3%).
- Eighteen additional serotypes were identified, indicating significant diversity.
- PFGE and MLST confirmed genetic heterogeneity; most isolates possessed key virulence genes.
- MLST revealed that wild boar S. suis isolates belonged to distinct clonal complexes, unrelated to those typically found in pigs or humans in Europe.
Conclusions:
- Wild boars are a common carrier of a genetically diverse range of Streptococcus suis strains.
- The identified S. suis strains carry virulence-associated genotypes.
- These strains appear to represent a distinct genetic lineage within wild boar populations, differing from those commonly implicated in pig and human infections.
