In vitro evaluation of gentamicin and teicoplanin release from cancellous human bone

Objectives: This study was designed to determine the in vitro antibacterial activity of gentamicin- or teicoplanin-impreg-nated human cancellous bone as a local antibiotic carrier. Methods: The study samples were obtained from human cancellous bone within the femur head in seven patients who underwent partial or total hip arthroplasty. Bone specimens were processed and incubated with gentamicin or teicoplanin for an hour. Control bone specimens were soaked in sterile saline solution for the same duration. Antibiotic release of bone specimens was assessed by the disc diffusion technique after 1, 3, 7, 10, 14. 18, and 21 days of antibiotic impregnation, with seven samples in each group. The test strains were E. coli ATCC 25922 for gentamicin, and S. aureus ATCC 25923 for teicoplanin. In vitro antibiotic efficacy was defined as an inhibition zone diameter of >15 mm for gentamicin, and >14 mm for teicoplanin. Results: Evaluation of inhibition zone diameters showed that bone + teicoplanin complexes had a longer duration of antibiotic release than that of bone + gentamicin complexes (12 to 18 days vs 7 to 10 days). There was no inhibition in the control group. There were no significant differences in inhibition zone diameters of teicoplanin- and gentami-cin-treated specimens on the first and third days; however, teicoplanin exhibited significantly greater zone diameters on the seventh (p=0.008) and tenth (p=0.003) days. Conclusion: Our data show that, under appropriate conditions, human cancellous bone incorporates a considerable amount of teicoplanin and exhibits effective antibiotic release for approximately two weeks.