The role of Staphylococcus aureus small colony variants in intraosseous invasion and colonization in periprosthetic joint infection

Medical Aims This study aimed to explore the role of small colony variants (SCVs) of Staphylococcus aureus in intraosseous invasion and colonization in patients with periprosthetic joint infection (PJI). Methods A PJI diagnosis was made according to the MusculoSkeletal Infection Society (MSIS) for PJI. Bone and tissue samples were collected intraoperatively and the intracellular invasion and intraosseous colonization were detected. Transcriptomics of PJI samples were analyzed and verified by polymerase chain reaction (PCR). Results SCVs can be isolated from samples collected from chronic PJIs intraoperatively. Transmission electron microscopy (TEM) and immunofluorescence (IF) showed that there was more S. au-reus in bone samples collected from chronic PJIs, but much less in bone samples from acute PJIs, providing a potential mechanism of PJI. Immunofluorescence results showed that SCVs of S. aureus were more likely to invade osteoblasts in vitro. Furthermore, TEM and IF also demonstrated that SCVs of S. aureus were more likely to invade and colonize in vivo. Cluster analysis and principal component analysis (PCA) showed that there were substantial differ-ences in gene expression profiles between chronic and acute PJI. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that these differential-ly expressed genes were enriched to chemokine-related signal pathways. PCR also verified these results. Conclusion Our study has shown that the S. aureus SCVs have a greater ability to invade and colonize in bone, resulting in S. aureus remaining in bone tissues long -term, thus explaining the patho-genesis of chronic PJI.

Automated summary

This study aimed to investigate the role of Staphylococcus aureus small colony variants (SCVs) in intraosseous invasion and colonization in patients with periprosthetic joint infection (PJI). The results showed that SCVs have a greater ability to invade and colonize bone, and there are significant differences in gene expression profiles between chronic and acute PJI. These findings are important for understanding the pathogenesis of chronic infections.