Effect of Fe and glucose on the glycolysis and gluconeogenesis in biofilm-associated Staphylococcus epidermidis

Abstract number: 1732_110

Massonet C., Pintens V., Merckx R., Van Eldere J.

Objective: To determine the role of GapA (glycolysis) and GapB (gluconeogenesis) in Staphylococcus epidermidis biofilms.

Methods: A biofilm-forming S. epidermidis strain from a proven catheter-related infection was used. For in vitro studies, to examine the influence of glucose, bacteria were grown overnight in BHI and re-incubated in BHI (glucose-rich; Fe-rich) or 0.9% NaCl (glucose-limited; Fe-rich). To examine the influence of iron (Fe) bacteria were grown overnight in RPMI without Fe (fRPMI) and re-incubated in fRPMI (glucose-rich; Fe-limited) or fRPMI with 25 mM Fe (glucose-rich; Fe-rich). For in vivo studies a subcutaneous rat model was used. Quantification of bacteria and gene expression through Taqman PCR were performed as described by S. Vandecasteele et al. (Biochem. Biophys. Res. Commun. 2002; 291: 528–534). Extracellular matrix and bacteria were visualised through confocal laser scanning microscopy (CLSM).

Results: In vitro, in a glucose-rich environment the expression of gapA and gapB did not differ between planktonic and sessile bacteria and stayed constant over time. Both in planktonic and sessile bacteria, expression of gapA was up-regulated in comparison to gapB. In vitro, in a glucose-limited environment, expression of gapA in sessile bacteria decreased in comparison to its expression in planktonic bacteria and expression of gapB in sessile bacteria increased to the expression level of gapA in sessile bacteria.

In vitro, in sessile bacteria, gapB expression was high in a medium with a low Fe content, irrespective of the glucose content. Simultaneously with the increased expression of gapB, PIA production could be visualised through CLSM in sessile bacteria in all media.

In vivo expression of gapA was high and remained constant over a period of two weeks. The expression of gapB decreased during the initial phase of implantation, but reached the expression level of gapA after two weeks of implantation.

Conclusion: The persistent expression of gapA in sessile bacteria could indicate a role in biofilm formation, especially in the early stages, while expression levels of gapB could indicate a role in the later phases of biofilm formation. Results of gene expression and CLSM indicate a link between gapB and PIA production that is influenced by both Fe and glucose.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
Back to top