Our previous clinical study supported the concept that capsular contracture is associated with subclinical infection of silicone implants. If bacterial presence, indeed, contributes to capsular contracture, then fibroblast behavior might be expected to change in the presence of bacteria by-products. Therefore, study of possible alteration of fibroblast behavior by bacteria products was undertaken using an in vitro model with cultured dermal fibroblasts. Coagulase-negative staphylococci from silicone mammary and penile implants were isolated and their phenotypic features were characterized. All represented nonbiofilm-producing strains. Products of isolate cultures were noncytotoxic and did not alter matrix reorganization (collagen gel contraction model) or collagen production by fibroblasts. Isolates from either mammary or penile implants exerted similar effects.