In this paper, the changes in the expression of some of the genes involved in S. epidermidis initial adhesion and biofilm formation on the surface of different biomaterials were analysed.
In order to study the genetic changes over the time, planktonic cells were incubated up to 48h with different biomaterials along with human serum proteins in order to mimic the in vivo environment.
The gene expression profile obtained was very similar in all the biomaterials used. A 10x up-regulation of atlE, gene that encodes the protein AtlE, that is known to be involved in initial adhesion, cell wall metabolism activity and pathogenesis, was detected 48h after contact with the biomaterials surface and human serum proteins.
Additionally, after 48h of incubation it was observed, respectively, 100 and 10x up-regulation of icaA, icaD, icaB and icaC, genes of the operon ica that is responsible for PNAG synthesis. An 10x up-regulation of the aap gene that codifies the accumulation associated protein Aap, was also observed.
Finally, gene expression profile of agr system during the 48h of incubation demonstrated that in the beginning of the biofilm formation agr system presented very low activity, starting to increase after 24h of incubation, as expected.
The overall results indicate that atlE and aap genes and ica and agr operons are essential for biofilm formation on the surface of medical devices in the presence of human serum proteins, independent of the type of the biomaterial used.
Despite the importance of this work, it is important to stress out that this study was limited in the number of genes and biomaterials tested.
Reference of the paper summarized above: