Experimental Model Of Osteomyelitis Research Articles

Особенности структурных изменений дистального суставного конца бедренной кости при экспериментальном моделировании остеомиелита

Features of structural changes in the joint components (synovial membrane, articular cartilage, subchondral bone) under the conditions of adjacent limb segment osteomyelitis are poorly understood and require thorough histological studies. Purpose Сomparative assessment of the structural reorganization of the main components of the distal articular end of the femur in experimental modeling of osteomyelitis. Material and methods Objects: distal metaphyses of the femur of intact rats (n = 5) and experimental ones (n = 16) in the conditions of modeled osteomyelitis of the femur. The culture of S. aureus was injected into the medullary canal in the experimental animals (n = 8) while saline was injected in the control group (n = 8). The animals were taken out of the experiment on the 21st day. Methods: histological, morphometric, and statistical methods were used. Results In the control group, the articular cartilage, subchondral bone plate, and subchondral zone retained their normal structure. Synovitis was not revealed. The values of the morphometric parameters were comparable with the intact norm. In the experimental group, bone microsequesters, osteoclastic resorption of the subchondral bone plate, inflammatory infiltration with the content of plasma cells and neutrophils were detected in the subchondral zone. Histological changes in the articular cartilage according to the classification of the International Society OARSI (2006) corresponded to grades 1 to 3 and were accompanied by synovitis. There was a significant (р < 0.05) decrease in the thickness of non-calcified cartilage, a significant twofold decrease in the thickness of the subchondral bone plate, while the values of the thickness of the calcified cartilage exceeded those in the control group and the intact norm. Conclusion Under the conditions of an experimental model of chronic osteomyelitis of the femur, the revealed structural changes in the subchondral zone contribute to the progression of the destruction of the subchondral bone plate, articular cartilage and synovitis. This model of chronic osteomyelitis can be used to experimentally study various therapeutic strategies aimed at modifying subchondral bone remodeling and relieving synovitis.

Rifaximine spacer application is not superior to local teicoplanin treatment in a rat model of osteomyelitis.

Acute and chronic osteomyelitis generally require long-term antibiotic therapy and surgical debridement. Implant-associated osteomyelitis, particularly from methicillin-resistant Staphylococcus aureus (MRSA) strains, is difficult to treat. Rifaximin is an antibiotic derived from rifamycin which may be effective in the treatment of osteomyelitis in terms of its wide spectrum of action and pharmacological properties. The aim of this experimental study was to investigate the local efficacy of rifaximin in rat models with MRSA and implant associated osteomyelitis. This study was carried out with 40 adult Wistar albino rats. The rats were randomly divided into 4 equal groups with 10 rats in each. An implant related MRSA osteomyelitis was created in the right tibia metaphysis of each rat by Norden's experimental osteomyelitis model. After 4 weeks, the implants of each tibia were removed and debridement was applied. Group 1 was designed as control group and no other treatment was applied other than debridement. Bone cement without any antibiotic was applied to Group 2, bone cement with teicoplanin was applied to Group 3 and bone cement with rifaximin was applied to Group 4. After 4 weeks from the second surgery, euthanasia was performed to the rats and the clinical, histopathological and microbiological results were compared. There was no statistically significant difference between the groups in clinical scoring. A statistically significant difference was found between the histopathological scores of Group 1 and Group 2 and the histopathological scores of Groups 3 and 4; the histopathological scores of Group 1 and Group 2 were found to be higher than Group 3 and Group 4. When the pre-and post-treatment colony numbers were compared, although there was a statistically significant difference between Group 3 and Group 2, no statistically significant difference was found between Group 4 and Group 1 results. In spite of its wide spectrum, the local efficacy of rifaximin in the treatment of osteomyelitis could not be demonstrated. This study shows the ability to shed light on some future comprehensive studies with the inclusion of infection markers.

Efficacy of apolipoprotein 2-Jifusheng in the treatment of osteomyelitis in rabbits

To evaluate the effect of one-stage treatment of bone morphogenetic protein 2 combined with Jifusheng in the experimental model of osteomyelitis in rabbits. The model of chronic osteomyelitis of tibia was established in 30 3-month-old male New Zealand white rabbits with a body weight of (2.0±0.5) kg, and the model was verified 4 weeks after operation. Thirty rabbits with osteomyelitis were randomly divided into 3 groups with 10 rabbits in each group (n= 10). The model group did not do any treatment after focal debridement, treatment group A was implanted with musculosheng at the site of focal debridement and bone defect, and treatment group B was implanted with apolipoprotein 2-Jifusheng at the site of focal debridement and bone defect. The therapeuticeffect was evaluated by blood biochemical, microbiological, imaging, pathological and immunohistochemical examination 8 weeks after operation. At 4 weeks after operation, 30 rabbits with osteomyelitis were successfully validated. The results of serological examination showed that the hypersensitive C-reactive protein (CRP) and white blood cell count(WBC)in the model group were significantly higher than those in the blank group at 2 and 4 weeks after operation. Eight weeks after treatment, the detection of blood indexes showed that the white blood cell count (WBC)and hypersensitive C reactive protein (CRP)in treatment group A and treatment group B were significantly lower than those in the model group (P<0.05), but there was no significant difference between treatment group An and treatment group B (P>0.05). Eight weeks after treatment, the bone defect area was measured. The bone volume/total volume (BV/TV) and bone mineral density (BMD)in treatment group A and B were significantly higher than those in the model group (P<0.05), and the bone volume/total volume (BV/TV) and bone mineral density(BMD)in treatment group B were significantly higher than those in treatment group A (P<0.05), the repair of bone defect was almost complete, and the bone volume and bone mineral density increased significantly. At 8 weeks after treatment, the number of osteoblasts/bone tissue area (N.Ob/T.Ar) and the number of osteoblasts/bone tissue perimeter (N.Ob/B.Pm) in treatment group A and B were significantly higher than those in model group, and the N.Ob/T.Ar and N.Ob/B.Pm in treatment group B were significantly higher than those in treatment group A. The immunohistochemical staining of TNF- α and IL-6 around bone tissue in treatment group A and treatment group B was significantly less than that in model group, but there was no significant difference between treatment group B and treatment group A. The combined application of apolipoprotein 2-Jifusheng can promote bone repair and reduce the inflammation of the focus. it can treat rabbits with osteomyelitis in one stage, provide objective basis for the formulation of clinical treatment strategy of osteomyelitis and further promote clinical research.

Dynamic of tissue changes in oneand twostage treatment of chronic osteomyelytis using bioresorbable matirial impregnated with vancomicin (comparative experimental morphological study)

The use of modern antibacterial agents and antiseptics in modern orthopedics does not always prevent infectious complications. Currently, two-stage surgical treatment with the implantation of an antimicrobial spacer is common. This method increases the duration of treatment, causing additional surgical trauma. The use of bioresorbable material with additional antibiotic impregnation simultaneously with the rehabilitation of the infectious focus can be considered a promising direction for improving the effectiveness of treatment of chronic osteomyelitis and reducing the treatment time of this group of patients. The main group consisted of rabbits with an experimental model of osteomyelitis followed by rehabilitation and one-stage replacement of the bone defect with bioresorbable material impregnated with vancomycin (n=12), and in animals of the comparison group (n=12) - two-stage surgical intervention with a similar material. Morphological studies were performed on animals of both groups on the 45th and 90th days after operations with replacement of a bone defect with a bioresorbable material with vancomycin. On the 45th day after the operation, the intensity of the processes of formation of newly formed bone tissue and restructuring of the osteoarthritis replacement material was more pronounced in the main group (28,2 vs 23,5%). Two-stage treatment is characterized by a more pronounced formation of fibrous tissue, the area of which in dynamics increased by 1,4 times (from 27,6 to 39,3%), with a single-stage method of treatment, this indicator increased only by 2% (from 22,9 to 24,9%). The infectious process was stopped in all experimental animals. The effectiveness of one-stage surgical treatment seems to be determined by a faster onset of osteohistogenesis in the area of a local osteomyelic defect when biocomposite is administered immediately after the purulent focus is sanitized. In addition, the absence of repeated surgical trauma with the loss of additional bone volume when removing the cement spacer during two-stage treatment is likely to play a significant role.

O tratamento com ozônio pode ser uma alternativa promissora para a osteomielite? Um estudo experimental.

Objetivo: O objetivo do presente estudo foi investigar o impacto bioquímico e histopatológico do tratamento de ozônio em modelo experimental de osteomielite em ratos.&#x0D; Métodos: Vinte e quatro ratos Sprague-Dawley machos adultos (3 meses de idade, pesando de 300 a 400 g) foram alocados randomicamente em três grupos. O grupo I (n = 8) serviu como controle. No Grupo II (n = 8), o modelo de osteomielite experimental foi induzido no fêmur e não foi aplicado nenhum tratamento. O grupo III (n = 8) recebeu tratamento com ozônio intraperitoneal por 3 semanas depois da formação de osteomielite no fêmur. Foram coletadas amostras de sangue para avaliar a capacidade antioxidante total (CAT), a concentração da proteína carbonil (PCO) e da lactato desidrogenase (LDH) no soro. As amostras do fêmur foram avaliadas por histopatologia quanto a inflamação, necrose, osteomielite e formação de abscesso.&#x0D; Resultados: Os níveis séricos de TAC foram notavelmente maiores (p &lt; 0,001), enquanto os níveis de LDH foram menores (p = 0,002) no Grupo III em comparação com o Grupo II. Nenhuma diferença significativa foi detectada entre os grupos com relação ao nível de PCO. Do mesmo modo, o Grupo III apresentou resultados histopatológicos mais favoráveis para osteomielite (p = 0,008), inflamação (p = 0,001), necrose (p = 0,022) e formação de abscesso (p = 0,022).&#x0D; Conclusão: O ozônio pode ser um tratamento adjuvante útil na osteomielite. Mais estudos com animais e com seres humanos são necessários para esclarecer e confirmar esses efeitos preventivos, compreender a fisiopatologia subjacente e estabelecer diretrizes. Nível de Evidência II; Estudo prospectivo comparativo.

Effects of Local Application of Nano-silver on Osteomyelitis and Soft Tissue Infections: An Experimental Study in Rats.

Purpose: Bone and soft tissue infections are among the least desired complications after orthopaedic surgery. This study analysed the in vivo effects of the local application of nano-silver particles (AgNPs) [1nm = 1 billionth of a meter] in soft tissue infections.Materials-Method: An experimental osteomyelitis model was formed by inoculating both tibias of 24 rats with methicillin-resistant Staphylococcus aureus. The rats were followed without treatment for 21 days. Blood samples and tibial x-rays at day 21 confirmed the development of infection. Then, the rats were divided randomly into two groups. One group (12 rats) underwent surgical debridement and received 21 days of teicoplanin therapy. The second group had the same treatment, with the addition of local nano-silver. All of the rats were sacrificed at day 42. Blood and wound swab samples were taken and the culture results were analysed.Results: No differences were observed between the groups in healing values at pathological examination, or in changes in the number of colonies at days 21 and 42. No differences in white blood cell count (WBC) were observed between the groups before and after the treatment.Conclusion: Although in vitro studies suggest the effectiveness of AgNPs on pathogens, we found that the application of nano-silver did not make any difference when used in addition to the classical osteomyelitis treatment with antibiotics and local surgical debridement. We believe that additional in vivo studies using repeated nano-silver application could be beneficial.

COULD OZONE TREATMENT BE A PROMISING ALTERNATIVE FOR OSTEOMYELITIS? AN EXPERIMENTAL STUDY.

ABSTRACTObjective:The aim of the present study was to investigate the biochemical and histopathological impact of ozone treatment in an experimental model of osteomyelitis in rats. Methods:A total of 24 adult male Sprague-Dawley rats (3 months old, each weighing 300 to 400 g) were randomly allocated into three groups. Group I (n=8) served as a control and received no interventions or medications. In Group II (n=8), osteomyelitis was induced in the femur and no treatment was applied. Group III (n=8) received intraperitoneal ozone treatment for 3 weeks after the formation of osteomyelitis in the femur. Serum samples were taken to assess total antioxidant capacity (TAC), protein carbonyl content (PCO), and lactate dehydrogenase (LDH). Bone specimens obtained from the femur were histopathologically evaluated for inflammation, necrosis, osteomyelitis, and abscess formation. Results:Serum TAC levels were notably higher (p<0.001), while LDH levels were lower (p=0.002) in Group III than Group II. No significant difference was detected between groups with respect to PCO level. Similarly, Group III displayed more favorable histopathological outcomes with respect to osteomyelitis (p=0.008), inflammation (p=0.001), necrosis (p=0.022), and abscess formation (p=0.022). Conclusion:Ozone may be a useful adjunct treatment for osteomyelitis. Further studies in animals and humans are needed to clarify and confirm these preventive effects, understand the underlying pathophysiology, and establish guidelines. Level of Evidence II; Prospective comparative study.

Staphylococcus aureus protein A enhances osteoclastogenesis via TNFR1 and EGFR signaling

Staphylococcus aureus is a major causative agent of osteomyelitis in adults and children. The increasing incidence of antimicrobial resistant isolates and the morbidity of this type of infection denote that alternative therapeutic approaches are required. S. aureus protein A interacts with TNFR1 and EGFR expressed at the surface of host cells. Given the importance of TNF-α and EGFR/RANKL crosstalk in enhancing osteoclast differentiation, the aim of this study was to determine the role of protein A in the induction of osteoclastogenesis and bone resorption during staphylococcal osteomyelitis. We determined that protein A plays a critical role in osteoclast differentiation and activation by initiating TNFR1 and EGFR mediated signaling. Moreover, we demonstrated that protein A significantly contributes to increased osteoclast differentiation and activation as well as cortical bone destruction during the course of disease using experimental models of osteomyelitis. Our findings strongly suggest targeting protein A and TNFR1 as an adjunctive strategy to control bone damage during the initial course of S. aureus osteomyelitis.

Treatment of Methicillin-resistant Staphylococcus aureus experimental Osteomyelitis with bone-targeted Vancomycin.

IntroductionMethicillin-resistant S. aureus (MRSA) is a common cause of bone and joint infection. BT2-peg2-vancomycin is an investigational bone-targeted formulation of vancomycin which we hypothesized would have increased antimicrobial activity compared to conventional vancomycin in a chronic experimental MRSA osteomyelitis model.MethodsWe tested bone affinity using an hydroxyapatite (HA) binding assay, assessed the in vitro antimicrobial susceptibility of 30 MRSA isolates, and compared vancomycin and BT2-peg2-vancomycin in a rat experimental osteomyelitis model.ResultsVancomycin did not bind to hydroxyapatite (HA binding index = 0), whereas BT2-peg2-vancomycin showed appreciable binding (HA binding index = 57). The MIC50 was 1 μg/ml and the MIC90 was 2 μg/ml for both vancomycin and BT2-peg2-vancomycin. The MBC90 was 16 and 4 μg/ml for vancomycin and BT2-peg2-vancomycin, respectively. Treatment with 50 mg/kg of vancomycin every 12 hours (median, 4.73 log10 cfu/g), 63.85 mg/kg (equivalent to 50 mg/kg vancomycin) of BT2-peg2-vancomycin every 12 hours (median, 3.93 log10 cfu/g) or 63.85 mg/kg of BT2-peg2-vancomycin once per week (median, 5.00 log10 cfu/g) was more active than no treatment (median, 5.22 log10 cfu/g) (P =0.0481). Treatment with 63.85 mg/kg of BT2-peg2-vancomycin every 12 hours was more active than all other treatment regimens evaluated (P≤0.0150), but was associated with high plasma BT2-peg2-vancomycin levels, decreased animal weight, increased kidney size, creatinine and BUN, and leukocytosis with tubulointerstitial nephritis.ConclusionWith optimization of pharmacokinetic parameters to prevent toxicity, BT2-peg2-vancomycin may be useful in the treatment of MRSA osteomyelitis.

Evaluation and Comparison of the Effects of Hyperbaric Oxygen and Ozonized Oxygen as Adjuvant Treatments in an Experimental Osteomyelitis Model

We evaluated and compared the efficacy of ozone (O(3)) and hyperbaric oxygen (HBO) therapies in an experimental rat model of osteomyelitis. Forty-eight male Sprague-Dawley rats were divided into sham, osteomyelitis (control), vancomycin (V), vancomycin + HBO (VHB), vancomycin + O(3) (VO), and vancomycin + HBO + O(3) (VOHB) groups. Osteomyelitis was induced by a bone injection of 10(8) CFU/mL methicillin-resistant Staphylococcus aureus. HBO was administered daily at 2.8-atm pressure for 90 min; O(3) therapy was provided as intraperitoneal injections of 0.7 mg/kg O(3)/O(2) gas mixture once daily. Treatments were continued from d 7 to 21 after induction of osteomyelitis. Bone tissues and blood samples were harvested for biochemical, histopathologic, and microbiologic analyses. Rats in the sham, VO, and VOHB groups gained weight but those in the control, V, and VHB groups did not. Levels of malondialdehyde, superoxide dismutase, and glutathione peroxidase were lower in the VHB, VO, and VOHB groups than in V and control groups. Levels of interleukin-10 and -1β and tumor necrosis factor-α were decreased in the VHB, VO, and VOHB groups; transforming growth factor-β was increased in these groups compared with V and control groups (P ≤ 0.001). Bacteria counts in VOHB were significantly lower than those in group of V (P = 0.012). Histopathologic scores in group VO were significantly lower than those in group V (P = 0.046). O(3) was as effective as HBO in decreasing oxidative parameters and inflammatory cytokines. Rats in the VO and VOHB groups gained more weight than did the other groups. Bacteria counts were significantly decreased in group VOHB compared with the other groups. Histopathologic scores in group VO were significantly decreased compared with the other groups.

Experimental Osteomyelitis Caused by Methicillin-ResistantStaphylococcus aureusTreated with a Polylactide Carrier Releasing Linezolid

The effectiveness of a new delivery system consisting of polymerized dilactide (PLA) with incorporated linezolid was investigated in a rabbit model as a means of treating methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis. The PLA-linezolid system was prepared after thorough stirring of PLA with linezolid at a 10:1 ratio. Experimental osteomyelitis was established in 40 rabbits by a modification of the Norden model with MRSA as the test isolate. After a hole had been drilled in the upper right femur, the isolate was inoculated using a thin needle working as a foreign body. At three weeks, the needle was removed and cultured, and the PLA-linezolid system was implanted in half the animals (group B); the remaining half was the control group (group A). Animals were sacrificed at regular intervals; tissue around the site of implantation was examined for pathologic changes and cultured quantitatively. The prepared system eluted linezolid in vitro at concentrations much greater than the minimum inhibitory concentration (MIC) of the test pathogen for 11 days. At three weeks after inoculation of the test isolate, all animals had osteomyelitis. By the sixth week, bacterial growth from cancellous bone of group B was significantly lower than that in group A. However, this effect was not maintained until the end of the study (weeks 8 and 10), when the differences in bacterial growth in the two groups were not significant. Polymerized dilactide mixed with 10% linezolid achieved partial arrest of the offending pathogen in an experimental model of osteomyelitis caused by MRSA.

In vitro and invivo release of cefuroxime axetil from bioactive glass as an implantable delivery system in experimental osteomyelitis

The aim of this study was to evaluate the characterisation, in vitro and in vivo biocompatibility and antimicrobial activity of bioactive glass (BG) impregnated with an antibiotic. The BG was prepared by normal glass melting procedures as a controlled release device to treat experimental osteomyelitis. The study design was for prospective in vivo experimental study. Two sets of porous bioactive glass ceramic blocks (9 mm × 4 mm × 4 mm and 20 mm × 9 mm × 9 mm) were fabricated using bioactive glass powder and subsequently antibiotic cefuroxime axetil (CFA) (55 and 125 mg on an average) was impregnated in these two sets of blocks, respectively. Osteomyelitis was produced in the right tibia of the rabbits according to the model of Norden. After thorough in vitro characterization of the porous blocks [including X-ray diffraction (XRD), Fourier-transformed infra-red spectroscopy (FTIR), thorough chemical analysis by inductively coupled plasma-atomic emission spectra (ICP-AES) and field-emission scanning electron microscopy (FESEM)] and in vitro elution of the said drug, in vivo test was carried out with rabbit species split into two groups: (a) animals treated with CFA impregnated bioactive glass and (b) parenteral [intra muscular (IM)] administration of CFA. Histological, radiological and drug concentration in bone and serum (measured by HPLC) in both groups were carried out. HPLC technique was used for determination of concentration both in vitro and in vivo. Fabricated porous struts showed amorphous microstructure without formation of any crystallite. The elution of said drug was stopped after 6 days in vitro. Histological studies at 3 and 6 weeks revealed formation of well-developed lamellar bone and havarsian canal. Radiological evaluation pointed out disappearance of sequestrum and existence of newly formed bony specules. Concentration of cefuroxime axetil in bone and serum showed highest value on day 21 which reduced marginally by day 42 and these values were higher than minimum inhibitory concentration (MIC) against Staphylococcus aureus (known pathogen for chronic osteomyelitis). It could be concluded that the biodegradable antibiotic carrier system developed in this study proved to be an effective therapeutic approach toward an experimental model of osteomyelitis. Based particularly on the in vivo results of the study, this cefuroxime axetil incorporated bioactive glass blocks can be successfully used in clinical cases of osteomyelitis in veterinary as well as human orthopaedic surgery.

In Vitro Elution of Daptomycin by a Synthetic Crystallic Semihydrate Form of Calcium Sulfate, Stimulan

A synthetic crystallic semihydrate form of calcium sulfate, Stimulan, was evaluated as a biodegradable carrier for the daily in vitro elution of daptomycin. Daptomycin and Stimulan were admixed at a ratio of 95:5. Elution lasted for 28 days. Eluted concentrations peaked on days 1 and 11, when the mean values were 1,320.1 and 949.2 microg/ml, respectively. The lowest eluted concentration was detected on day 28. These results support the application of the system described in experimental models of osteomyelitis.

In vitro elution of moxifloxacin from cancellous bone allografts

The characteristics of cancellous bone allografts as carriers of moxifloxacin are described. Particles of cancellous bone were compressed into a wire-mesh cylinder and impregnated into a solution of moxifloxacin for different time periods. Five replicas were impregnated for 1 h; another five for 24 h; and another five for 48 h. Impregnated allografts were then transferred into vials containing 5 ml of Mueller-Hinton broth and incubated at 37 degrees C. Broth was replaced daily. Concentrations of moxifloxacin in broth were determined after analysis by an high performance liquid chromatography system. Moxifloxacin was eluted at very high concentrations within the first days. Concentrations remained above 100 microg/ml until day 8 and above 40 microg/ml until day 20. It is concluded that cancellous bone allografts may allow the adequate in vitro elution of moxifloxacin. The latter results support their application in experimental models of osteomyelitis.

Effect of age on cytokine response in an experimental model of osteomyelitis

To study the effect of age on cytokine response in an experimental model of osteomyelitis. Forty adult male Wistar rats received a stainless steel needle, intramedullarly in the left tibia. Young rats (3 months old) and old rats (22 months old) were allotted in: Group A: Sterile implant. Group B: Sterile implant + slime producing S. aureus. Rats were sacrificed 9 weeks after surgery. Determinations: Cytokines (ELISA) in blood and in tibia extract and the number of bacteria in tibia and implant. The Wilcoxon, Mann-Whitney U tests were used (P < or = 0.01 significant). Infection was detected in every old rat receiving S. aureus, and in 7 of 10 young rats. In blood: prior to surgery, old rats presented higher IL-2 and lower IL-4 levels. Surgery alone did not induce significant changes in old rats; surgery + S. aureus induced significant increases of IL-2 and IL-10 in young rats, and of IL-6 in old rats. Tibia analysis S. aureus group showed increased levels of: IL-10 in young rats, and IL-1beta in old rats. In experimentally induced osteomyelitis, significant differences were observed in cytokine response with regard to age.

In Vitro Release of Fusidic Acid and Teicoplanin from Cancellous Bone Allografts

The characteristics of cancellous bone allografts as carriers of fusidic acid and teicoplanin are described. Particles of cancellous bone were compressed into a wire-mesh cylinder; five replicas were impregnated for one hour into fusidic acid; and another five for one hour into teicoplanin. Elution was estimated daily. Concentrations of fusidic acid and teicoplanin were determined by a microbiological assay. Both antibiotics were eluted at very high concentrations within the first days. Allografts impregnated in fusidic acid provided concentrations above 20 μg/ml for 20 days. Eluted teicoplanin after day 4 was below 10 μg/ml. It is concluded that cancellous bone allografts may allow adequate In Vitro elution of fusidic acid but not of teicoplanin. The latter results support their application in experimental models of osteomyelitis.

In vitro elution of moxifloxacin and fusidic acid by a synthetic crystallic semihydrate form of calcium sulphate (Stimulan™)

Stimulan™ was evaluated in vitro as a biodegradable carrier for local delivery of moxifloxacin and fusidic acid. Moxifloxacin or fusidic acid was mixed with calcium sulphate at a ratio of 95:5 to prepare five replicas per antibiotic. In vitro elution was estimated daily using a high-performance liquid chromatography (HPLC) system. Elution of moxifloxacin lasted for 31 days. Eluted concentrations reached their peak on Day 13 (mean level 745 μg/mL); the lowest eluted concentration was detected on Day 30 (mean level 367 μg/mL). Elution of fusidic acid lasted for 14 days. Eluted concentrations reached their peak on Day 6 (mean value 249.5 μg/mL); the lowest eluted concentration was detected on Day 13 (mean value 10.9 μg/mL). The presented results revealed that Stimulan™ may allow adequate in vitro elution of moxifloxacin and fusidic acid. The latter results support the application of this system in experimental models of osteomyelitis.

Efficacy of ciprofloxacin implants in treating experimental osteomyelitis

Ciprofloxacin (CFX) implants containing poly(D,L-lactide) and calcium phosphates (tricalcium phosphate and hydroxyapatite) was evaluated in 50 rabbits in an experimental osteomyelitis model. Their femoral cavity was inoculated with Staphylococcus aureus. After 2 weeks, the infected focus was cleaned out and the delivery system implanted. The infection and subsequent response to treatment were evaluated by microbiological analysis, biochemical and hematological markers, body weight, temperature, clinical signs, X-rays, and histology. Infected bone cultures, treated with CFX implants, showed reduced bacterial growth against controls. All CFX was released within 6 weeks. All animals recovered within 4 weeks. Even 12 weeks after implantation, no recurrence of infection was observed. Serum C-reactive protein, platelet, and leukocyte levels increased in all animals before treatment, and 4 weeks after it were maintained or rose in control animals, while decreased to normal levels in treated ones. Body weight was characterized by pretreatment losses, then gains during recuperation, or further loss in untreated animals; with no significant intraindividual differences in body temperature. Body weight, leucocytes, platelets, and C-reactive protein turned out to be highly useful markers for monitoring this kind of infection and its treatment. CFX implants demonstrated to be an effective therapy for S. aureus bone infection. Their efficacy was also reflected in decreasing severity of clinical signs, nonprogress of radiological signs indicative of infection, and good integration into bone structure. Histological examination revealed repair, with new bone formation extending into implants.

Apatite cement containing antibiotics: efficacy in treating experimental osteomyelitis

Osteomyelitis is generally treated by the systemic administration of antibiotics and continuous irrigation after curettage of the lesion, and bone graft is performed secondarily to treat any bone defect. This treatment is associated with major invasion, and also has adverse effects on other organs. If a superior bone filling material were to be developed that allowed high concentrations of antibiotics that acted only locally, and allowed bone formation at the same time, an ideal method of treating osteomyelitis would become available. We created an implant composed of calcium phosphate cement, gentamicin, and poly-L-lactic acid. The results of sustained-release testing in vivo and in vitro demonstrated the release of effective antibiotic concentrations over a 2-month period. Further, when an experimental model of osteomyelitis was produced in rabbits and the implant was inserted after bone marrow curettage, the implant proved effective in preventing the progression of osteomyelitis and in achieving local bone formation.

Phosphate tricalcique, vecteur d'antibiotiques: étude sur foyer d'ostéomyélite expérimentale chez le lapin

Purpose of the study Macroporous beta tricalcium phosphate ceramic beads were elaborated to be a resorbable bone substitute and a drug delivery system carrying gentamicin or vancomycin. The aim of this study was to evaluate this implant into a rabbit experimental osteomyelitis. Material and method Experimentation included 24 rabbits and was performed in three stages, according to Norden's description. Induction of osteomyelitis was obtained by injection of a sclerosing agent and of Staphylococcus aureus through the lateral side of the metaphysis of the proximal tibia. Three weeks after inoculation, animals were randomly dispatched to one of the three treatment groups. After surgical debridment (to collect cinetics data), the first group received no further treatment and was considered as a control; the second group received a ceramic implant; the third group received a gentamicinloaded ceramic implant. Euthanasia occurred between 2 days and 21 days after the debridment. Bone samples were obtained to quantify the bacterial and gentamicin bone concentrations. Gentamicin level was also measured inside the ceramic implant. Antibiotic concentration was assessed by a immunoenzymatic method. Results Osteomyelitis was obtained in 21 of the 24 animals (87.5%). Antibiotic release was early and complete (before the third day) but gentamicin still remained in the bone for 10 days. Bacterial concentration suggested an antimicrobial activity of the implant, but not a full sterilisation of the osteomyelitis. Conclusion Norden's experimental osteomyelitis model with rabbit was proposed to assess the therapeutic activity of systemic antibiotics, but not to evaluate biomaterials. Therefore we have shifted for experimental evaluation of biomaterials to a metaphyseal osteomyelitis in the sheep, the patterns of which are close from those of the human disease.