Experimental Polymorphism Survey in Intergenic Regions of the icaADBCR Locus in Staphylococcus aureus Isolates from Periprosthetic Joint Infections

Abstract

Staphylococcus aureus is a leading cause of prosthetic joint infections (PJI) characterized by bacterial biofilm formation and recalcitrance to immune-mediated clearance and antibiotics. The molecular events behind PJI infection are yet to be unraveled. In this sense, identification of polymorphisms in bacterial genomes may help to establish associations between sequence variants and the ability of S. aureus to cause PJI. Here, we report an experimental nucleotide-level survey specifically aimed at the intergenic regions (IGRs) of the icaADBCR locus, which is responsible for the synthesis of the biofilm exopolysaccharide PIA/PNAG, in a collection of strains sampled from PJI and wounds. IGRs of the icaADBCR locus were highly conserved and no PJI-specific SNPs were found. Moreover, polymorphisms in these IGRs did not significantly affect transcription of the icaADBC operon under in vitro laboratory conditions. In contrast, an SNP within the icaR coding region, resulting in a V176E change in the transcriptional repressor IcaR, led to a significant increase in icaADBC operon transcription and PIA/PNAG production and a reduction in S. aureus virulence in a Galleria mellonella infection model. In conclusion, SNPs in icaADBCR IGRs of S. aureus isolates from PJI are not associated with icaADBC expression, PIA/PNAG production and adaptation to PJI.

Antibiofilm Effect of Silver Nanoparticles in Changing the Biofilm-Related Gene Expression of Staphylococcus epidermidis

“…The performed experiments indicate that the role of the icaR gene in inhibiting biofilm formation is also important. As reported in the work of Morales-Laverde et al, nucleotide polymorphism in the icaR coding region leads to an increase in icaADBC transcription and PIA production [ 31 ]. Similar results were reported by Wang et al, who demonstrated an increase in the expression of the icaR gene and a decrease in the expression of the icaA gene with the use of silver nanoparticles [ 32 ].…”

Functional analysis of intergenic regulatory regions of genes encoding surface adhesins in Staphylococcus aureus isolates from periprosthetic joint infections

“…In the case of S. aureus , SNPs accumulation in the IGRs of adhesin-encoding genes present in strains isolated from later points of infection has been described [ 48 ]. On the contrary, regarding the production of the main exopolysaccharide of the S. aureus biofilm matrix, SNPs in the highly conserved IGRs of the icaADBCR operon were not associated with changes in icaADBC expression, PIA/PNAG production and adaptation to PJI [ 29 ].…”

“…The forty-five PJI S. aureus strains were previously isolated at Sahlgrenska Hospital (Sweden) from PJI of the hip or knee [ 27 , 28 ]. Twenty-six strains from wound infections, isolated between 1966 and 2010, were obtained from the Culture Collection University of Gothenburg (CCUG) [ 29 , 30 ]. Escherichia coli and S. aureus were grown in Luria-Bertani medium (LB; Conda-Pronadisa, Madrid, Spain) and Trypticase soy broth (TSB; Conda-Pronadisa, Madrid, Spain) at 37 °C.…”

“…Whole genome sequencing of PJI and wound isolates was previously performed [ 27 , 29 ]. The Sequence Read Archives (SRAs) including comprehensive data on the strains were submitted to the National Center for Biotechnology Information (NCBI) and given the BioProject accession number PRJNA765573.…”

Analysis of the association between polymorphisms in intergenic regions of Staphylococcus aureus genes involved in biofilm formation and periprosthetic joint infections

“…were obtained from the Culture Collection University of Gothenburg (CCUG)(Morales-Laverde et al, 2022;Turner et al, 2022). Escherichia coli and S. aureus strains were routinely grown in Luria-Bertani medium (LB; Conda-Pronadisa, Madrid, Spain) and Trypticase soy broth (TSB; Conda-Pronadisa, Madrid, Spain), respectively, at 37°C.…”