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Genomic characterization of beta-haemolytic streptococci isolated from prosthetic joint infections
Niklas Löwbeer1, Marc Stegger1,2, Bo Söderquist1
1School of Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
Abstract:
Prosthetic joint infection (PJI) is an increasing concern for the medical profession, as higher numbers of arthroplasty surgeries lead to rising PJI-related costs. Streptococcal PJIs constitute approximately 10% of PJIs, but their genetic features and characteristics remain largely unexplored. Little is known about antimicrobial resistance (AMR) rates, whether some sequence types (ST) dominate, and whether certain virulence-associated genes are overrepresented. We used whole-genome sequencing of Streptococcus dysgalactiae (n = 22), Streptococcus agalactiae (n = 10) and S. pyogenes (n = 1) to elicit genomic data on 33 beta-haemolytic streptococci isolated from PJIs in Region Örebro county, Sweden. Relatedness was inferred based on single nucleotide polymorphisms in S. dysgalactiae and S. agalactiae. The genomic data were screened for virulence-associated genes available in the Virulence Factor Database. All isolates were screened for both phenotypic and genotypic resistance. The S. dysgalactiae and S. agalactiae isolates were genetically diverse, although 32% of S. dysgalactiae isolates (n = 7) were ST20. The speS and PI-2A genes were less represented in these isolates among virulence-associated genes, and AMR was more frequently observed in S. agalactiae. We conclude that PJIs caused by beta-haemolytic streptococci are not dominated by genetically similar beta-haemolytic streptococci. There were distinct inter-species differences in AMR between S. agalactiae and S. dysgalactiae.
Insights
Prosthetic joint infections (PJIs) caused by beta-hemolytic streptococci show genetic diversity, with no single sequence type dominating. Antimicrobial resistance patterns differ between Streptococcus agalactiae and Streptococcus dysgalactiae species.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Prosthetic joint infection (PJI) is a growing concern with increasing arthroplasty surgeries.
- Streptococcal PJIs account for 10% of cases, yet their genetic makeup and antimicrobial resistance (AMR) remain understudied.
- Understanding these characteristics is crucial for managing PJI costs and outcomes.
Purpose of the Study:
- To investigate the genomic features and AMR profiles of beta-hemolytic streptococci causing PJIs.
- To determine if specific sequence types (STs) or virulence genes are prevalent in these infections.
- To compare genetic diversity and AMR between Streptococcus dysgalactiae and Streptococcus agalactiae in PJIs.
Main Methods:
- Whole-genome sequencing was performed on 33 beta-hemolytic streptococci isolates (22 S. dysgalactiae, 10 S. agalactiae, 1 S. pyogenes) from PJIs.
- Genetic relatedness was assessed using single nucleotide polymorphisms.
- Isolates were screened for virulence-associated genes and both phenotypic and genotypic AMR.
Main Results:
- The S. dysgalactiae and S. agalactiae isolates exhibited significant genetic diversity.
- A specific sequence type, ST20, was identified in 32% of S. dysgalactiae isolates.
- Antimicrobial resistance was more common in S. agalactiae than in S. dysgalactiae, with distinct inter-species differences observed.
Conclusions:
- PJIs caused by beta-hemolytic streptococci are not dominated by a single, genetically uniform group.
- Distinct inter-species variations in AMR exist between S. agalactiae and S. dysgalactiae.
- Further research into specific virulence factors like speS and PI-2A may be warranted.
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