Fig. 3

Microbiological evaluation in each treatment group. A SEM scanning of the implant with high magnification (× 5000). B Five fields of view (FOV) on each implant were randomly observed under high magnification (× 5000) and counted. n = 5. C Representative tryptic soy agar (TSA) plates of microbial culture of bone, soft tissue and implant in each treatment group. D The mean CFUs counts of the L5 centrum in each treatment group. E The mean CFUs counts of all soft tissues around the L5 centrum in each treatment group. F The mean CFUs counts of implant in each treatment group. G The mean CFUs counts of the whole animal in each treatment group. n = 8. CON: control (no antibiotics); SV: system vancomycin (88 mg/kg, intraperitoneal injection, half an hour pre-surgery); VP 0.5: intra-wound vancomycin powder, 44 mg/kg, once before the closure of incision intraoperatively; VP 1.0: intra-wound vancomycin powder, 88 mg/kg; VP 2.0: intra-wound vancomycin powder, 176 mg/kg. Data were compared by an unpaired 1-tailed Mann–Whitney test. *P < 0.05, **P < 0.01 (compared with CON group), ^##P < 0.01 (compared with SV group), ^ΔΔP < 0.01 (compared with VP0.5 group). ^□□P < 0.01 (compared with VP1.0 group). The red arrow indicates MRSA, the blue triangle indicates leukocyte, and the yellow circle indicates erythrocyte