Biofilm Formation on Breast Implant Surfaces By Major Gram-Positive Bacterial Pathogens.

BACKGROUND Bacterial biofilm on surfaces of mammary implants is a predisposing factor for several outcomes. Since Gram-positive bacteria are potential agents of biomaterial-associated infections (BAIs), their abilities to form biofilm on breast implants should be elucidated. OBJECTIVES To evaluate biofilm formation on different mammary prosthesis surfaces by major Gram-positive bacterial pathogens involved in BAIs. METHODS We initially evaluated biofilm formation on polystyrene plates with and without fibrinogen or collagen for one reference strain and one clinical isolate of Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus pyogenes. We also tested the ability of clinical isolates to form biofilm on four different implant surfaces: polyurethane foam and smooth, microtextured and standard textured silicone. Biofilm structure and cell viability were observed by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). RESULTS All strains showed strong biofilm formation on polystyrene. After fibrinogen or collagen treatment, biofilm formation varied. With fibrinogen, reference strains of S. aureus and S. pyogenes increased biofilm formation (p<0.05). Reference strains of all species and the clinical isolate of S. pyogenes increased biofilm formation after collagen treatment (p<0.05). In general, S. aureus showed higher capacity to produce biofilm. SEM showed biofilm attached to all surfaces tested, with the presence of extracellular polymeric substances and voids. Viable cells were more frequent for E. faecalis and S. pyogenes. CONCLUSIONS All species produced biofilm on all prosthesis surfaces and under different conditions. Micrographies indicated thicker bacterial biofilm formation on microtextured and/or standard textured silicone by all species, except E. faecalis.