Diffusion of antibiotics across tissue expanders: an in vitro study

Local infection remains a significant complication of tissue expansion. Subclinical infection of pockets with permanent prosthesis used in breast reconstruction has also been associated with capsular contracture around the implant. In an in vitro model, we used four groups of eighteen 50-ml tissue expanders, each containing Bactrim, Ancef, Nafcil, or saline only, in beakers containing fresh frozen plasma, placed in a rotary shaker for 48 hours. Inoculums of Staphylococcus aureus and Staphylococcus epidermidis were then selectively added to the medium external to the expanders in each group. The growth of such strains was found to be variably inhibited. We thus determined that antibiotics can diffuse through a tissue expander's Silastic membrane and establish an efficient bacteriostatic level in the surrounding fluid. This information could have potential clinical application in reducing infections associated with the use of expanders.