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The coupled effects of physicochemical and flow conditions on Staphylococcus epidermidis adhesion and ica genes expression

Abstract number: P697

Foka A., Katsikogianni M., Chini V., Missirlis Y., Anastassiou E.D., Spiliopoulou I.

Objectives: Meticillin resistant Staphylococcus epidermidis (MRSE) is the predominant species associated with medical device infections impeding their long-term use. The critical step to development of infections is bacterial adhesion to biomaterials mediated by non specific interactions, as well as bacterial slime production encoded by the ica operon. The coupled effects of specific chemical terminal surface groups and flow conditions on the initial adhesion of S. epidermidis were investigated in correlation to the expression of two genes of the ica operon.

Methods: Reference control strains (ATCC35984, slime-positive and ATCC12228, slime-negative), and two clinical strains isolated from different hospitalised patients, (one ica-positive/slime-positive and one ica-positive/slime-negative) were investigated. Bacteria were grown in BHI medium and then suspended in physiological saline at a concentration of ~3×109 cells/mL. Hydroxyl (OH)-terminated (hydrophilic) and methyl (CH3)-terminated (hydrophobic) glass surfaces were used as substrates in a parallel flow chamber. Bacterial adhesion was examined under two flow rates: 2mL/min and 20mL/min for four hours. Total RNA from both bacterial supernatant (s) and adherent (a) bacteria after detachment with trypsin, was isolated by the Trizol method. Reverse transcription followed by quantitative Real-Time PCR (qRT-PCR) allowed the detection of expression levels of icaA and icaD. Table 1 summarizes the results.

Table 1: Quantification of icaA and icaD expression by qRT-PCR

Conclusions: Surface chemistry and flow conditions influence the expression level of both ica genes. Hydrophobic biomaterial surfaces and faster flow rate seem to play a crucial role to initial adherence increasing ica gene expression.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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