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Biofilm-production is strongly correlated with the presence of accumulation associated protein

Abstract number: R2261

Karanika M., Iliopoulos D., Vergi M., Koutsia-Carouzou C., Angelou K., Malizos K., Petinaki E.

Objectives: The implication of biofilm in chronic bacterial infection in many species has triggered an increasing interest in the characterisation of proteins involved in biofilm formation. The purpose of this study was to investigate the role of polysaccharide intercellular adhesin (PIA), accumulation associated protein (Aap) and biofilm-associated protein (Bap) in biofilm formation among Staphylococcus hominis.

Methods: A total of 50 genetically unrelated Staphylococcus hominis, recovered from various orthopaedic clinical specimens were tested for biofilm-production by Christensen, and for the production of PIA, AAP and BAP. Staphylococcal cells were suspended in 100 mM PBS containing 5 mM EDTA and 1 mM PMSF. Cells were centrifuged, and suspended in 1 ml digestion buffer [50 mM Tris/HCl pH 7.5, 20 mM MgCl2 and 30% raffinose (Sigma)]. To each sample protease inhibitors (Complete cocktail; Roche), and lysostaphin (Sigma) were added, and the suspension was incubated in a 37°C water bath for 30 min. After centrifugation at 6000 g, the supernatant fraction, which contained the wall-associated proteins, was analysed by SDS-PAGE (4–20% separation gel). PIA was detected with the PIA-specific antiserum (1:5,000), AAP was detected with AAP-antiserum (1:2,500 dilution) and BAP was detected by anti-Bap serum (1:2,000 dilution). Bound antibodies were visualised by anti-rabbit immunglobulin G-alkaline phosphatase conjugate (1:5000; Sigma).

Results: Eighteen out of fifty S. hominis tested (36%) were found to be biofilm-producers. Among them, 88.8%, 50% and 38.8%, respectively were found to produce AAP, PIA and BAP. Strong production was detected in six strains (33.3%) that simultaneously expressed AAP, PIA and BAP. A week biofilm production was associated with the combination of AAP and BAP, or AAP and PIA in two independent strains, while detection alone of PIA was found in two strains.

Conclusions: These results clearly demonstrate that PIA is not the only protein responsible for biofilm-production, but other proteins, such as AAP, also play a crucial role.

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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