Background: Staphylococcus epidermidis is a primary cause of breast implant-associated infection. S epidermidis possesses several virulence factors that enable it to bind both abiotic surfaces and host factors to form a biofilm. In addition S epidermidis colocalizes with matrix proteins coating explanted human breast implants.
Objectives: The authors sought to identify matrix proteins that S epidermidis may exploit to infect various breast implant surfaces in vitro.
Methods: A combination of in vitro assays was used to characterize S epidermidis strains isolated from human breast implants to gain a better understanding of how these bacteria colonize breast implant surfaces. These included determining the (1) minimum inhibitory and bactericidal concentrations for irrigation solutions commonly used to prevent breast implant contamination; (2) expression and carriage of polysaccharide intercellular adhesin and serine-aspartate repeat proteins, which bind fibrinogen (SdrG) and collagen (SdrF), respectively; and (3) biofilm formation on varying implant surface characteristics, in different growth media, and supplemented with fibrinogen and Types I and III collagen. Scanning electron microscopy and immunofluorescence staining analyses were performed to corroborate findings from these assays.
Results: Textured breast implant surfaces support greater bacterial biofilm formation at baseline, and the addition of collagen significantly increases biomass on all surfaces tested. We found that S epidermidis isolated from breast implants all encoded SdrF. Consistent with this finding, these strains had a clear affinity for Type I collagen, forming dense, highly structured biofilms in its presence.
Conclusions: The authors found that S epidermidis may utilize SdrF to interact with Type I collagen to form biofilm on breast implant surfaces.
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