Phenotype and gene feature analysis of a novel tool bacterium of staphylococcal aureus for studies in prosthetic joint infections

Abstract

Objective To determine whether a periprosthetic joint infections (PJI) patient derived S. aureus is an appropriate candidate tool bacterium for studying the pathogenesis of S. aureus-induced PJI. Methods Whole genome sequencing data of ST1792 was obtained using the Illumina Hiseq platform of a Staphylocuccal. aureus(S. aureus) strain derived from a PJI prosthesis, and gene functional enrichment analysis based on gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) database was performed. Besides, its biofilm formation ability in drainage fluid, synovial fluid and human plasmin were compared to that in experimental cultures, in order to determine differences in biofilm forming ability in different environment. In addition, based on Illumina Hiseq platform, transcriptome analysis of the S. aureus in the three types of fluid above was performed to determine its gene expression profile and functional enrichment analysis of the differentially expressed genes was conducted through the GO and KEGG database. Finally, adaptability in different human fluid of the S. aureus was analyzed with the transcriptome profile and biofilm formation data. Results The genome of ST1792 consisted of 2 718 coding sequences, including main virulence encoding genes and regulation related genes. Functional enrichment showed no sign of significant missing or major recombination in the bacterial genome. The biofilm mass in plasmin was much higher than that in synovial fluid, both significantly higher than the biofilm mass in TSB. But the biofilm mass in drainage fluid was not statistically different from that in TSB. This revealed that the bacterial biofilm phenotype was significantly altered in PJI human fluid. Transcriptomics sequencing revealed that a huge number of genes were differentially expressed in drainage fluid, synovial fluid and human plasmin compared to TSB. Functional enrichment revealed that the bacterial gene expression profile was different in PJI human fluids, which showed the sophisticated adaptation of the bacterium to human fluid environment. Conclusion As a clinical S. aureus isolated from a PJI patient, ST1792 presents distinct phenotypes and adaptations in vivo, so it is a proper candidate for future studies in the pathogenesis of S. aureus induced PJI. Key words: Biofilms; Prosthesis-related infections; Staphylococcus aureus; Genomics