Article Figures & Data
Figures
- FIG 1
In-vitro time-kill study. The results represent the viable count (in number of CFU per milliliter) of Staphylococcus aureus strain S54F9 in the time-kill experiment with different gentamicin concentrations (16, 160, 1,600, 16,000, and 160,000 times the MIC). On the x axis, 0 represents the number of CFU just before gentamicin exposure. The dotted line at a value of 2 CFU/ml on the y axis represents the detection limit.
- FIG 2
Results of sonication and histological registrations. (A) The number of bacteria attached to the implants was reduced with the increasing values of the MIC of gentamicin added to the inoculum. (B and C) The width of the peri-implant pathological bone area (PIBA) (B) and the count of neutrophilic granulocytes (C) were increased only in animals inoculated with bacteria and with bacteria plus 160× MIC gentamicin. Single values and the mean and standard error of the mean (SEM) are shown for each group.
- FIG 3
Macroscopic bone pathology. Three pigs were inoculated with Staphylococcus aureus and gentamicin at different MICs in the right tibia, followed by insertion of a steel implant. The pigs were euthanized 5 days after inoculation. The tibial bone was sagittally sectioned, and the implant was removed for demonstration of the implant cavity (IC). (A) Pig inoculated with bacteria and 160,000× MIC of gentamicin. No pus was visible, and the implant cavity is regular. (B) Pig inoculated with bacteria and 160× MIC gentamicin. Pus and bone destruction surround the implant cavity. (C) Pig inoculated with bacteria and 1,600× MIC of gentamicin. Although there was less pus than in the image in panel B, the bone contour of the implant cavity was still destroyed (inset).
- FIG 4
Microscopic bone pathology. Two were pigs inoculated with Staphylococcus aureus and different MICs of gentamicin in the right tibia, followed by insertion of a steel implant. The pigs were euthanized 5 days after inoculation. The tibial bone was sagittally sectioned, and the implant was removed for demonstration of the implant cavity (IC). (A) Pig inoculated with bacteria and 160× MIC of gentamicin. HE stain was used. The arrow indicates the extension of the peri-implant pathological bone area (PIBA). PIBA contains necrotic bone tissue and a massive infiltration of neutrophilic granulocytes and macrophages. (B) Pig inoculated with bacteria and 160,000× MIC of gentamicin. HE stain was used. PIBA is small (double arrow), and only a sparse inflammatory reaction was present. (C) Close-up of the image in panel A. A microabscess that contained small aggregates of bacteria (arrow) and that was surrounded by multinuclear giant cells is seen. (D) Within the microabscess, S. aureus was detected immunohistochemically. Red positive bacteria (arrow) can be seen among the neutrophilic granulocytes (NG).
- FIG 5
Inoculation procedure in a porcine model of implant-associated osteomyelitis. (A) A small incision down to the periosteum was made on the medial side of the proximal right tibia, and a 4-mm K wire (arrow) was drilled 2 cm into the bone to establish the implant cavity. (B) The inoculum containing S. aureus bacteria and different concentrations of gentamicin (arrow) was injected into the implant cavity. (C) After inoculation, a steel implant of 2 by 15 mm (made from a K wire) was inserted into the implant cavity, and the periosteum was closed with sutures (arrow), followed by closure of the soft tissue and skin. (D) Fluoroscopy just after the operation. The implant (arrow) is seen in the implant cavity.
Tables
- TABLE 1
Overview of study groups and detection of bacteria postmortem
Group Animal no. Inoculum Detection of bacteria in implant cavity (swab) Detection of biofilm in: Implant (sonication) Tissue around implant cavity (IHCa) A A1 Saline No No A2 Saline No No A3 Saline No No A4 Saline No No No A5 Saline No No No A6 Saline No No No B B1 S. aureus Yes (inoculated spa type) Yes Yes B2 S. aureus Yes (inoculated spa type) Yes No B3 S. aureus Yes (inoculated spa type) Yes Yes B4 S. aureus Yes (inoculated spa type) Yes Yes B5 S. aureus Yes (inoculated spa type) Yes Yes B6 S. aureus Yes (inoculated spa type) Yes Yes C C1 S. aureus + 160× MIC (40 mg/liter) Yes (inoculated spa type) Yes Yes C2 S. aureus + 160× MIC Yes (inoculated spa type) Yes No C3 S. aureus + 160× MIC Yes (inoculated spa type) Yes Yes D D1 S. aureus + 1,600× MIC (400 mg/liter) Contamination Yes No D2 S. aureus + 1,600× MIC Yes (inoculated spa type) Yes No D3 S. aureus + 1,600× MIC Yes (inoculated spa type) No No E E1 S. aureus + 16,000× MIC (4,000 mg/liter) No Yes Yes E2 S. aureus + 16,000× MIC No No No E3 S. aureus + 16,000× MIC Yes (inoculated spa type) Yes No F F1 S. aureus + 160,000× MIC (40,000 mg/liter) No No No F2 S. aureus + 160,000× MIC Yes (inoculated spa type) Yes No F3 S. aureus + 160,000× MIC No No No F4 S. aureus + 160,000× MIC No No No ↵a IHC, immunohistochemistry for S. aureus.
