This study was undertaken to evaluate the risk of
infection (defined as the recovery of the relevant organism from the implant site) in a mouse model when low numbers of bacteria were present on an implanted
biomaterial. Segments of different types of
suture with adherent bacteria were implanted subcutaneously into mice. The
infection risk with Staphylococcus aureus was greater than with Staphylococcus epidermidis RP62A or Candida albicans. The
infection risk with the implantation of multifilament
sutures was significantly greater than with monofilament
sutures. When <10 colony forming units (cfu) of S. aureus were present on monofilament
suture material, the
infection rate was 3%. When <10 cfu of S. aureus were present on multifilament
suture material, the
infection rate was 7%. An
infection rate of 15% occurred with <10 cfu of S. aureus on multifilament
nylon sutures. When >10 but <20 cfu of S. aureus were present, the
infection rates were 4 and 51%, respectively. These data confirm that the
infection rate with multifilament
sutures (or porous materials) is greater than with monofilament
sutures (or solid materials) when the organisms are encountered at implantation (acute model) and indicate that a significant risk of
infection may occur when only a few organisms are on a device at implantation.