Relation between 20-kDa polysaccharide and polysaccharide intercellular adhesin of Staphylococcus epidermidis
Abstract number: P1970
Spiliopoulou A., Kolonitsiou F., Krevvata M.I., Karamanos N.K., Dimitracopoulos G., Harris L.G., Wilkinson T.S., Davies A.P., Mack D., Anastassiou E.D.
Objectives: Extracellular polysaccharide molecules from S. epidermidis have proved notoriously difficult to characterise as numerous original descriptions of unique molecules have ultimately been confirmed to be closely related or identical to Polysaccharide Intercellular Adhesin (PIA). In the present work (ESCMID09 Fellowship) we have investigated the relation of 20-kDa PS and PIA.
Methods: 75 CoNS strains isolated from blood cultures and central venous catheter tips in the Clinical Laboratory of the General University Hospital of Patras, Greece, were identified at the species level and screened for biofilm formation, icaADBC presence, and 20-kDa PS expression. Nine different S. epidermidis reference strains were also used in the present study. Parallel screening of reference and selected clinical strains for 20-kDa PS and PIA using specific anti-20-kDa PS and anti-PIA rabbit antisera was performed. Susceptibility of both antigens to certain chemicals and enzymes was examined by treatment of bacterial suspensions with sodium meta-periodate, proteinase K and specific N-acetylglucosaminidase, Dispersin B (DspB). Antigen detection was accomplished by immunofluorescence microscopy and ELISA.
Results: Among the clinical isolates, 20 strains were found to be ica+biofilm+20kDaPS+, 10 ica-biofilm-20kDaPS-, 6 ica+biofilm-20kDaPS+, 6 ica-biofilm-20kDaPS+, 5 ica+biofilm-20kDaPS- and 5 strains ica+biofilm+20kDaPS-. All other CoNS were ica-20kDaPS-. All PIA positive reference strains (1457, 8400, and 9142) were 20-kDa PS positive, whereas, a PIA negative strain (1585) was also 20-kDa PS negative. Expression of 20-kDa PS does not seem to be related to icaADBC activity or biofilm formation as isogenic icaA::Tn917 PIA-negative mutants (1457-M10 and 8400-M10) were still 20-kDa PS positive. 20-kDa PS is resistant to treatment with proteinase K, sodium meta-periodate and DspB, whereas, PIA is resistant to proteinase K but sensitive to sodium meta-periodate treatment and DspB. Fractions of Q-Sepharose containing the PIA-antigenic peak were devoid of 20-kDa PS. Finally, the two molecules have distinct antigenic properties, as shown by cross absorption experiments.
Conclusions: 20-kDa PS is a main antigenic determinant of S. epidermidis. Our data show that 20-kDa PS is distinct from PIA. It is therefore of great importance to elucidate its biologic properties and role in pathogenesis of biomaterial-associated infections by constructing isogenic mutant(s) devoid of 20-kDa PS.
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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