| 【Objective】Implant related infection(IRI)is one of the most challenging problems in orthopedics and trauma surgery.The prevention and treatment of IRI has become the core of current clinical research,especially the antibacterial coating on the surface of internal plants.The research of layer materials has received increasing attention and attention.Based on the previous literature review and a series of basic experimental studies,our team prepared a new type of iodine-coated titanium implant through the use of Povidone Iodine(PVP-I)by electrophoresis deposition method.In vivo experiments have verified that it has exact antibacterial properties against Staphylococcus aureus.In this study,the antibacterial activity of the iodine-loaded implant against Gram-negative bacteria was further evaluated and determined by constructing a rabbit model of experimental osteomyelitis of the tibial cortex associated with Escherichia coli.【Methods】1.Preparation of iodine-coated titanium implants:16 titanium alloy Kirschner wires with a length of 12mm and a diameter of 1mm were selected in this experiment,with regular shapes and smooth surfaces.Among them,8 titanium alloy K-wires are in the School of Materials and Engineering,Fuzhou University.In the laboratory,PVP-I is used for surface treatment of iodine.2.Construction of rabbit tibial osteomyelitis model:Select the standard strain of Escherichia coli(ATCC 25922),select 16 adult healthy New Zealand rabbits,and randomly divide them into an iodine-coated group(numbered E1-E8)and a non-iodine-coated group(numbered C1-C8).After successful anesthesia,all experimental animals were drilled and windowed on the proximal tibia on the left side,and then treated in groups:the iodine-coated group(8 animals)was first implanted with iodine-coated titanium alloy K-wires,and then Use a pipette to inject 25ul of 2×10~8CFU/ml bacterial suspension into the bone marrow cavity,and seal the bone hole with bone wax;the non-iodine-coated group(8):first implant the non-iodine-coated titanium alloy K-wires,and then transfer The liquid gun injects 25ul of 2×10~8CFU/ml bacterial suspension into the bone marrow cavity,and similarly seals the bone hole with bone wax.Iodophor disinfects the wound,sutures with silk thread,covers the wound with sterile gauze,and bandages it.All animals were kept in cages for 1 week after operation,and evaluated and analyzed by general conditions,microbiology,histopathology,scanning electron microscopy,CLSM confocal microscopy and other methods after 1 week.【Results】On the third day after the operation,one New Zealand rabbit in the non-iodine group died,and the remaining animals survived 1 week after the operation.1.General condition and visual score:The wound of the affected limb in the iodine-loaded group is generally in good condition,with no obvious signs of infection,while the affected limb in the non-iodine-coated group has obvious signs of wound infection.The P value of the two groups’wound scores is 0.008(P<0.05),the difference is statistically significant.2.In the microbiological statistics:3 of the 8 bacterial cultures in the iodine-coated group were positive,with a positive rate of 37.5%;5 of the 7 bacterial cultures in the non-iodine-coated group were positive,with a positive rate of 71.4%.3.Histopathological evaluation results:7bone tissue specimens in the non-iodine-coated group and 8 bone tissue samples in the iodine-coated group showed different degrees of bone infection under the light microscope.All specimens showed varying numbers of neutrophils gathered in the interstitial space of adipocytes in the medullary cavity,with more than 10 neutrophils per high-power field.And all specimens showed one or more microabscesses.In the part of cortical bone,both groups of specimens showed cortical bone destruction and local enlarged Harvard’s system.Local fracture and enlargement of the cortical bone were more common in the specimens without iodine,and the degree of cortical bone destruction was less in the specimens with iodine.4.Observed by scanning electron microscopy:E.coli can be observed in all 5 samples of the non-iodine-coated group,and the positive rate is 100%.Among the 7 samples of the iodine-coated group,4 samples are occasionally found in E.coli,and the positive rate is57.1%,and the number of Escherichia coli attached to the surface of the titanium K-wires in the non-iodine-coated group was significantly more than that in the iodine-coated group.5.CLSM observation results:6 specimens of the non-iodine-coated group and 5 specimens of the iodine-coated group can be observed with different numbers of bacteria attached to the surface of the titanium K-wires,and the positive rate of the specimens is 100%.【Conclusion】1.In this study,a rabbit tibial osteomyelitis model was constructed for in vivo antibacterial experiments.The comparison of microbiology,histopathology,scanning electron microscopy,CLSM and other examination results shows that the iodine-coated titanium implant can effectively inhibit E.coli in the early stage of infection.It further verified the excellent antibacterial properties of the iodine-coated titanium implant developed by this research group.2.In this study,a stable infection model of E.coli related tibial osteomyelitis was constructed by using an inoculum amount of 5×10~6CFU.All in all,we believe that the antibacterial properties of the new iodine-coated titanium implants developed in the early stage of this research group are clear in vivo and in vitro,and have high research value and application prospects in the field of clinical orthopedics. |
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