Bacterial colonization of bone allografts: establishment and effects of antibiotics.
BACKGROUND
Bone grafts are frequently used to supplement bone stock and to establish structural stability. However, graft-associated infection represents a challenging complication leading to increased patient morbidity and healthcare costs.


OBJECTIVE
We therefore designed this study to (1) determine if increasing initial S. aureus inoculation of bone allograft results in a proportionate increase in colonization; (2) assess if antibiotics decrease colonization and if antibiotic tethering to allograft alters its ability to prevent bacterial colonization; and (3) determine if covalent modification alters the allograft topography or its biological properties.


METHODS
Allograft bone and vancomycin-modified bone (VAN-bone) was challenged with different doses of S. aureus for times out to 24 hours in the presence or absence of solution vancomycin. Bacterial colonization was assessed by fluorescence, scanning electron microscopy (SEM), and by direct colony counting. Cell density and distribution of osteoblast-like cells on control and modified allograft were then compared.


RESULTS
Bacterial attachment was apparent within 6 hours with colonization and biofilm formation increasing with time and dose. Solution vancomycin failed to prevent bacterial attachment whereas VAN-bone successfully resisted colonization. The allograft modification did not affect the attachment and distribution of osteoblast-like cells.


CONCLUSIONS
Allograft bone was readily colonized by S. aureus and covered by a biofilm with especially florid growth in natural topographic niches. Using a novel covalent modification, allograft bone was able to resist colonization by organisms while retaining the ability to allow adhesion of osteoblastic cells.


CONCLUSIONS
Generation of allograft bone that can resist infection in vivo would be important in addressing one of the most challenging problems associated with the use of allograft, namely infection.
Ketonis
Constantinos
C
Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA, USA.
Barr
Stephanie
S
Adams
Christopher S
CS
Hickok
Noreen J
NJ
Parvizi
Javad
J
D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D018786:Bone Substitutes; D016025:Bone Transplantation; D066298:In Vitro Techniques; D019736:Prostheses and Implants / Q000382:microbiology*; D016459:Prosthesis-Related Infections / Q000517:prevention & control; D013203:Staphylococcal Infections / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D014184:Transplantation, Homologous; D014640:Vancomycin / Q000737:chemistry / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D018786:Bone Substitutes; D014640:Vancomycin