Chronic Bone Infections Research Articles

Exosomes derived from bone marrow mesenchymal stem cells induce the proliferation and osteogenic differentiation and regulate the inflammatory state in osteomyelitis in vitro model.

Chronic osteomyelitis is a chronic bone infection characterized by progressive osteonecrosis and dead bone formation, which is closely related to persistent infection and chronic inflammation. Exosomes derived from bone marrow-derived mesenchymal stem cells (BMSC) play an important role in bone tissue regeneration and the modulation of inflammatory processes. However, their role and mechanism of action in osteomyelitis have not been reported so far. This paper explores the potential effect of BMSC-derived exosomes on osteomyelitis in vitro model with the aim of providing a theoretical basis for the treatment of osteomyelitis in the future. In this study, exosomes were isolated and extracted from BMSCs and identified. MC3T3-E1 cells were treated with Staphylococcal protein A (SPA) to establish an in vitro model of osteomyelitis. Next, the effects of BMSC-derived exosomes on cell proliferation, apoptosis, angiogenesis, and autophagy in MC3T3-E1 cells treated with SPA were evaluated. Results showed that the proliferation ability of MC3T3-E1 cells increased after co-culture with BMSC-derived exosomes. Moreover, exosomes induced autophagy and osteogenic differentiation in MC3T3-E1 cells. The mRNA and protein levels of factors related to proliferation, differentiation, apoptosis, autophagy, and angiogenesis including β-Catenin, Runx2, Bcl-2, VEGFA, and Beclin-1 upregulated in SPA-treated MC3T3-E1 cells, whereas the levels of inflammatory cytokines including TNF-α, IL-1β, and IL-6 decreased in the supernatant. The results showed that exosomes derived from BMSCs may participate in the attenuation of osteomyelitis by inducing proliferation and osteogenic differentiation and regulating the inflammatory state in bone cells.

Cutibacterium acnes invades submicron osteocyte lacuno-canalicular networks following implant-associated osteomyelitis.

Cutibacterium acnes, part of normal skin flora, is increasingly recognized as an opportunistic pathogen capable of causing chronic prosthetic joint infections (PJI) associated with total hip and knee arthroplasty. However, there is a paucity of literature examining the pathogenesis of C. acnes during PJI. To study this, we developed an implant-associated osteomyelitis murine model in which 8-10-week-old C57BL6 mice were subjected to transtibial implantation of titanium or stainless-steel L-shaped pins contaminated with C. acnes. Postsurgery, mice were killed on Days 14 and 28 for terminal assessments of (1) bacterial load in bone, implant, and internal organs (heart, spleen, kidney, and liver), (2) bone osteolysis (micro-CT), (3) abscess formation (histology), and (4) systematic electron microscopy (EM). In vitro scanning EM (SEM) confirmed that C. acnes can form biofilms on stainless-steel and titanium implants. In mice, C. acnes could persist for 28 days in the tibia. Also, we observed C. acnes dissemination to internal organs. C. acnes chronic osteomyelitis revealed markedly reduced bone osteolysis and abscess formation compared to Staphylococcus aureus infections. Importantly, transmission EM (TEM) investigation revealed the presence of C. acnes within canaliculi, demonstrating that C. acnes can invade the osteocyte lacuno-canalicular networks (OLCN) within bone. Our preliminary pilot study, for the first time, revealed that the OLCN in bone can be a reservoir for C. acnes and potentially provides a novel mechanism of why C. acnes chronic implant-associated bone infections are difficult to treat.

Adenosquamous Cell Carcinoma Secondary to Chronic Osteomyelitis of the Tibia - Rare Case Report

Osteomyelitis is an infection with progressive destruction of bone tissue involving the bone and articular cartilage with its medullary canal. Chronic osteo-myelitis treatment is challenge for the orthopaedician. The bone microscopic anatomy and also the microorganism biofilms and their ability to adapt to their surrounding environment. It’s tough for the antibiotics and disinfectants to breach the biofilm barrier and kill these microorganism colonies. Cutaneous neoplasm are a rare complication developing after a chronic bone infection. The incidence and prevalence of these cutaneous tumor/neoplasm following chronic bone infection continues to increase despite the increasing awareness to the disease process, and medical advances in early diagnosis and early treatment. Most common neoplasm after a chronic bone infection are squamous cell carcinoma and rarely sarcoma or lymphoma. 1 In our study we report adenosquamous cell carcinoma arising from chronic osteomyelitis of tibia for which above knee amputation was done.

Local delivery of linezolid in the treatment of complex orthopedic bone and joint infections in patients with vancomycin allergy: a case series.

Introduction: Osteomyelitis is a challenging bone infection associated with ischemia, trauma, or various surgical procedures (e.g., joint reconstruction). Treatment involves eradicating infected bone and soft tissue, local antibiotic delivery, and a 6-week course of antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) infections are common, and vancomycin is the standard treatment, but alternatives like linezolid are needed in vancomycin-resistant and vancomycin-allergic patients. Methods: A retrospective chart review was conducted on patients treated by the senior author between 2013 and 2021. The study included patients who received local delivery of linezolid for bone and/or joint infection with documented evidence of vancomycin allergy. Patient demographics, surgical details, linezolid delivery method, and outcomes were recorded. Clinical outcomes and subsequent procedures leading to infection eradication were documented. Results: A total of 13 patients were treated with linezolid-antibiotic-laden spacers with polymethyl methacrylate (PMMA) carrier. Nine patients were successfully treated using limb-salvage techniques and were still infection-free after a mean follow-up of 55.5 months. Conclusions: Linezolid-loaded bone cement is an option for managing chronic bone and joint infections, particularly MRSA, in patients with vancomycin allergy.

A Review of the Clinical Utilization of Oral Antibacterial Therapy in the Treatment of Bone Infections in Adults.

Chronic osteomyelitis in adults is managed with prolonged courses of intravenous antibiotics in conjunction with surgical debridement of necrotic bone. Over the past 40 years, there has been no paradigm shift in this approach, as randomized controlled trials of this standard of care compared to alternatives such as prolonged oral antibiotics are scarce. However, there have been many small trials, case reports, and review papers evaluating the effectiveness of oral treatment for chronic osteomyelitis. The oral route for infections requiring prolonged treatment is intuitively and practically more favorable due to several advantages, the most important of which is the avoidance of long-term IV antimicrobial therapy with its complications, inconvenience, and cost. In this paper, we review the literature evaluating oral antibiotic therapy in the management of chronic bone infections since 1975. The majority of osteomyelitis infections are caused by Staphylococcus aureus, hence we focus on its treatment using oral antibiotics; however, we also emphasize subpopulations of patients with diabetes, implanted hardware, and with less common bacterial organisms. The primary objective of this review is to promulgate clinical recommendations on the use of oral antibiotics in bone infections in the context of initial therapy, transition from intravenous therapy, and the role of chronic suppression. The secondary objective is to summarize current knowledge of the specific oral antimicrobial agents that are commonly utilized, together with a synopsis of the available literature pertaining to their pharmacokinetic/pharmacodynamic properties and duration of therapy in bone infection.

Augmentation with a non-vascularized autologous fibular graft for the management of Cierny-Mader type IV chronic femoral osteomyelitis: a salvage procedure.

The study aimed to evaluate preliminary clinical and radiographic results of patients with Cierny-Mader type IV chronic femoral osteomyelitis and augmented with a non-vascularized fibular autograft as a salvage procedure because of the poorly regenerated new bone after bone transport over an intramedullary nail (BTON). Patients diagnosed with CM type IV chronic femoral bone infection and treated with BTON procedure between 2003 and 2020 were retrospectively reviewed. Seven patients were included in the study whose distraction gap was poorly regenerated and then augmented with a non-vascularized fibular autograft. A three-stage treatment was administered. First, the infection was eradicated. Second, BTON was performed. Third, the poorly regenerated distraction gap was augmented with a fibular autograft before removing the external fixator (EF). Clinical and radiological results were evaluated based on the criteria described by Paley-Maar and Li classification. The mean patient age was 52 years. The mean treatment time was 24.8 months, with a mean femoral lengthening of 12.6 cm. The mean EF and bone healing indexes were 0.57 months/cm and 0.8 months/cm, respectively. The mean length of the fibular graft was 13 cm. The bone healing of new bones was achieved in all patients with good quality after grafting. Functional scores were excellent in four patients. No patients experienced any sequelae. Non-vascularized fibular autograft augmentation may be an effective salvage procedure for poorly regenerated new bone after BTON to manage chronic femoral bone infection.

Staphylococcus aureus planktonic but not biofilm environment induces an IFN-β macrophage immune response via the STING/IRF3 pathway

ABSTRACT Chronic implant-related bone infections are a severe complication in orthopaedic surgery. Biofilm formation on the implant impairs the immune response, leading to bacterial persistence. In a previous study, we found that Staphylococcus aureus (SA) induced interferon regulatory factor 3 (IRF3) activation and Ifnb expression only in its planktonic form but not in the biofilm. The aim of this study was to clarify the role of the stimulator of interferon genes (STING) in this process. We treated RAW 264.7 macrophages with conditioned media (CM) generated from planktonic or biofilm cultured SA in combination with agonists or inhibitors of the cyclic GMP-AMP synthase (cGAS)/STING pathway. We further evaluated bacterial gene expression of planktonic and biofilm SA to identify potential mediators. STING inhibition resulted in the loss of IRF3 activation and Ifnb induction in SA planktonic CM, whereas STING activation induced an IRF3 dependent IFN-β response in SA biofilm CM. The expression levels of virulence-associated genes decreased during biofilm formation, but genes associated with cyclic dinucleotide (CDN) synthesis did not correlate with Ifnb induction. We further observed that cGAS contributed to Ifnb induction by SA planktonic CM, although cGAS activation was not sufficient to induce Ifnb expression in SA biofilm CM. Our data indicate that the different degrees of virulence associated with SA planktonic and biofilm environments result in an altered induction of the IRF3 mediated IFN-β response via the STING pathway. This finding suggests that the STING/IRF3/IFN-β axis is a potential candidate as an immunotherapeutic target for implant-related bone infections.

Treating methicillin-resistant Staphylococcus aureus (MRSA) bone infection with focused ultrasound combined thermally sensitive liposomes

Objective Chronic bone infection caused by Staphylococcus aureus biofilms in children and adults is characterized by reduced antibiotic sensitivity. In this study, we assessed ‘heat-targeted, on-demand’ antibiotic delivery for S. aureus killing by combining ciprofloxacin (CIP)-laden low-temperature sensitive liposomes (LTSLs) with local high-intensity focused ultrasound (HIFU) induced bone heating in a rat model of bone infection. Methods CIP-LTSLs were prepared using the thin-film hydration and extrusion method. Bone infection was established by surgically implanting an orthopedic K-wire colonized with methicillin-resistant S. aureus (MRSA) strain into rat’s femurs. For bone heating, ultrasound-guided HIFU exposures were performed to achieve a local temperature of 40–42 °C (∼15 min) concurrently with intravenous injection of CIP-LTSLs or CIP. CIP biodistribution was determined spectrophotometrically and therapeutic efficacy was determined by bacteriological, histological and scanning electron microscopy (SEM) analyses. Results CIP-LTSLs in the range of 183.5 nm ± 1.91 showed an encapsulation efficiency of >70% at 37 °C and a complete release at ∼42 °C. The metal implantation method yielded medullary osteomyelitis characterized by suppurative changes (bacterial and pus pockets) by day 10 in bones and adjoining muscle tissues. HIFU heating significantly improved CIP delivery from LTSLs in bones, resulting in a significant reduction in MRSA load compared to HIFU and CIP alone groups. These were also verified by histology and SEM, wherein a distinct reduction in S. aureus population in the infected metal wires and tissues from the combinatorial therapy was noted. Conclusion HIFU improved CIP delivery to bones, achieving clearance of hard-to-treat MRSA biofilms.

Antimicrobial Stewardship for Outpatients with Chronic Bone and Joint Infections in the Orthopaedic Clinic of an Academic Tertiary Hospital, South Africa.

Bone and joint infections are associated with prolonged hospitalizations, high morbidity and complexity of care. They are difficult to treat, and successful therapy requires organism-specific antimicrobial therapy at high doses for a prolonged duration as recommended in standard treatment guidelines (STGs). Adherence to the treatment plan is equally important, which is enhanced with knowledge of the condition as well as appropriate antibiotics. Consequently, the aim of this study was to provide antimicrobial stewardship (AMS) services to outpatients with chronic bone and joint infections presenting to the orthopaedic clinic at a public South African tertiary hospital. A total of 44 patients participated in this study. Chronic osteomyelitis was diagnosed in 39 (89%) patients and septic arthritis in 5 (11%). The majority (43%) of infections were caused by Staphylococcus aureus followed by Pseudomonas aeruginosa (14%). Seventy-one antibiotics were prescribed at baseline with rifampicin prescribed the most (39%), followed by ciprofloxacin (23%). The majority (96%) of the antibiotics were not prescribed according to the South African STG; however, interventions were only needed in 31% of prescribed antibiotics (n = 71) since the STG only recommends empiric therapy directed against Staphylococcus aureus. Seventy-seven percent of the patients obtained a high self-reported adherence score at baseline. Consequently, there is a need to improve AMS in bone and joint infections to improve future care.

Fabrication of injectable antibiotic-loaded apatitic bone cements with prolonged drug delivery for treating post-surgery infections.

Antibiotic-loaded bioactive bone substitutes are widely used for treating various orthopedic diseases and prophylactically to avoid post implantation infection. Calcium deficient hydroxyapatite (also known as apatitic bone cement) is a potential bioactive bone substitute in orthopedics due to its chemical composition similar to that of natural bone minerals. In this study, fabrication of mannitol (a solid porogen) incorporated injectable synthetic (Syn) and eggshell derived (ESD) apatitic bone cements loaded with antibiotics (gentamicin/meropenem/ rifampicin/vancomycin) was investigated. The release kinetics of the antibiotics were studied by fitting them with different kinetic models. All the antibiotics-loaded apatitic bone cements set within clinically accepted setting time (20 ± 2 min) and with good injectability (>70%). The antibiotics released from these bone cements were found to be controlled and sustained throughout the study time. Weibull and Gompertz (applies in least initial burst and sustain drug release rate models) were the best models to predict the release behavior. They cements had acceptable compressive strength (6-10 MPa; in the range of trabecular bone) and were biodegradable (21%-27% within 12 weeks of incubation) in vitro in simulated body fluids at physiological conditions. These bone cements showed excellent antibacterial activity from day 1 onwards and no bacterial colony was found from day 3 onwards. The viability of MG63 cells in vitro after 72 h was significantly higher after 24 h (i.e., ~110%). The cells were well attached and spread over the surface of the cements with extended morphology. The ESD antibiotic-loaded apatitic bone cements showed better injectability, degradation and cytocompatibility compared when compared to Syn antibiotic-loaded apatitic bone cements. Thus, we believe that the ESD antibiotic-loaded apatitic bone cements are suitable as potential injectable bone substitutes to avoid post-operative implant associated and other acute or chronic bone infections.

Evaluation of the In Vitro Antimicrobial Efficacy against Staphylococcus aureus and epidermidis of a Novel 3D-Printed Degradable Drug Delivery System Based on Polycaprolactone/Chitosan/Vancomycin-Preclinical Study.

Acute and chronic bone infections, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA), remains a major complication and therapeutic challenge. It is documented that local administration of vancomycin offers better results than the usual routes of administration (e.g., intravenous) when ischemic areas are present. In this work, we evaluate the antimicrobial efficacy against S. aureus and S. epidermidis of a novel hybrid 3D-printed scaffold based on polycaprolactone (PCL) and a chitosan (CS) hydrogel loaded with different vancomycin (Van) concentrations (1, 5, 10, 20%). Two cold plasma treatments were used to improve the adhesion of CS hydrogels to the PCL scaffolds by decreasing PCL hydrophobicity. Vancomycin release was measured by means of HPLC, and the biological response of ah-BM-MSCs growing in the presence of the scaffolds was evaluated in terms of cytotoxicity, proliferation, and osteogenic differentiation. The PCL/CS/Van scaffolds tested were found to be biocompatible, bioactive, and bactericide, as demonstrated by no cytotoxicity (LDH activity) or functional alteration (ALP activity, alizarin red staining) of the cultured cells and by bacterial inhibition. Our results suggest that the scaffolds developed would be excellent candidates for use in a wide range of biomedical fields such as drug delivery systems or tissue engineering applications.

Staphylococci planktonic and biofilm environments differentially affect osteoclast formation

IntroductionThe pathophysiology of chronic implant-related bone infections is characterized by an increase in osteoclast numbers and enhanced bone resorption. Biofilms are a major reason for chronicity of such infections as the biofilm matrix protects bacteria against antibiotics and impairs the function of immune cells. Macrophages are osteoclast precursor cells and therefore linked to inflammation and bone destruction.Objective and methodInvestigations on the impact of biofilms on the ability of macrophages to form osteoclasts are yet missing and we, therefore, analyzed the effect of Staphylococcus aureus (SA) and Staphylococcus epidermidis (SE) planktonic and biofilm environments on osteoclastogenesis using RAW 264.7 cells and conditioned media (CM).ResultsPriming with the osteoclastogenic cytokine RANKL before CM addition enabled the cells to differentiate into osteoclasts. This effect was highest in SE planktonic or SA biofilm CM. Simultaneous stimulation with CM and RANKL, however, suppressed osteoclast formation and resulted in formation of inflammation-associated multinucleated giant cells (MGCs) which was most pronounced in SE planktonic CM.ConclusionOur data indicate that the biofilm environment and its high lactate levels are not actively promoting osteoclastogenesis. Hence, the inflammatory immune response against planktonic bacterial factors through Toll-like receptors seems to be the central cause for the pathological osteoclast formation. Therefore, immune stimulation or approaches that aim at biofilm disruption need to consider that this might result in enhanced inflammation-mediated bone destruction.

Bacterial and Metabolic Factors of Staphylococcal Planktonic and Biofilm Environments Differentially Regulate Macrophage Immune Activation

Biofilm formation is a leading cause for chronic implant-related bone infections as biofilms shield bacteria against the immune system and antibiotics. Additionally, biofilms generate a metabolic microenvironment that shifts the immune response towards tolerance. Here, we compared the impact of the metabolite profile of bacterial environments on macrophage immune activation using Staphylococcus aureus (SA) and epidermidis (SE) conditioned media (CM) of planktonic and biofilm cultures. The biofilm environment had reduced glucose and increased lactate concentrations. Moreover, the expression of typical immune activation markers on macrophages was reduced in the biofilm environment compared to the respective planktonic CM. However, all CM caused a predominantly pro-inflammatory macrophage cytokine response with a comparable induction of Tnfa expression. In biofilm CM, this was accompanied by higher levels of anti-inflammatory Il10. Planktonic CM, on the other hand, induced an IRF7 mediated Ifnb gene expression which was absent in the biofilm environments. For SA but not for SE planktonic CM, this was accompanied by IRF3 activation. Stimulation of macrophages with TLR-2/-9 ligands under varying metabolic conditions revealed that, like in the biofilm setting, low glucose concentration reduced the Tnfa to Il10 mRNA ratio. However, the addition of extracellular L-lactate but not D-lactate increased the Tnfa to Il10 mRNA ratio upon TLR-2/-9 stimulation. In summary, our data indicate that the mechanisms behind the activation of macrophages differ between planktonic and biofilm environments. These differences are independent of the metabolite profiles, suggesting that the production of different bacterial factors is ultimately more important than the concentrations of glucose and lactate in the environment.

Five-year outcomes after bypass graft versus Fogarty balloon catheter for the treatment of acute blunt popliteal artery injury.

To evaluate long-term clinical outcomes after revascularization by bypass graft versus Fogarty balloon catheter in acute blunt popliteal artery injury and identify risk factors contributing to amputation. A retrospective review was conducted in patients treated for acute blunt PAI between 2011 and 2019. Inclusion criteria were patients who underwent bypass graft and Fogarty balloon catheter. The cumulative limb salvage rate was calculated by the Kaplan-Meier test and compared with Breslow-Wilcoxon test. Cox proportional hazard model was performed to estimate the potential risk factors for amputation. Receiver operating characteristic (ROC) curve was used to determine the optimal cut-off value for the potential risk factors. The overall limb salvage rate was 60.4% (29/48), including 24 patients (66.7%) in bypass graft, and 5 patients (41.7%) in Fogarty balloon catheter with mean follow-up of 5years (range, 2-10years). Among amputees, 15 patients (15/19, 78.9%) received primary amputation due to vascular failure or severe soft tissue damage, and 4 received secondary amputation because of chronic bone infection or neurologic deficit. Kaplan-Meier curves showed patients who received Fogarty balloon catheter had significantly higher amputation rate than those received bypass graft, with a hazard ratio of 3.801 (95% CI: 1.162-12.43, p = 0.009). In addition, Cox proportional hazard model revealed that MESS was the only independent risk factor for patients developing amputation, and the optimal cut-off value of MESS was 8. Five-year outcome demonstrated that Fogarty balloon catheter is not a safe procedure and has significantly higher amputation rate in severe blunt PAI. MESS is the only risk factor for amputation.

Extensive Actinomycetoma Clinical Manifestations and Histopathology: A Case Report

Background: Actinomycetoma is a chronic infection of cutis, subcutaneous, bone, and viscera tissue. It is characterized by sinuses containing masses of causative organisms often referred to as "grains." Actinomycetoma is caused by aerobic bacteria, and they have been misclassified as a fungal species. Diagnosis of actinomycetoma was based on clinical features and confirmation by direct examination. This study aimed to describe the clinical and histopathological features of actinomycetoma.
 Case presentation: A 34-year-old woman complained of a mass on her left leg that had increased in number and pain 3 months before admission to the hospital with a history of trauma. Regio pedis sinistra has trias mycetoma, such as edema (swelling), multiple sinuses, and grain with hypertrophic scars. Histopathological with fibro collagenous connective tissue, moderate to dense diffuse PMN inflammatory cells, plasma cells, lymphocytes, hemosiderophages, multinucleated giant cells, epithelioid cells, and microorganisms. In periodic acid Schiff (PAS) there is the Splendore-Hoeppli phenomenon.
 Conclusion: Diagnosis of actynomycetoma was confirmed by the mycetoma triad and the Splendore-Hoeppli phenomenon. Actinomycetoma is more invasive and can cause bone destruction more quickly than eumycetoma.

Dual drug delivery system of teicoplanin and phenamil based on pH-sensitive silk fibroin/sodium alginate hydrogel scaffold for treating chronic bone infection.

For effective treatment of infected bone, it is essential to use local drug delivery systems with the ability to deliver both antibiotics and osteoinductive factors. Herein, a pH-sensitive silk fibroin (SF)/sodium alginate (SA) hydrogel scaffolds containing teicoplanin (TEC) and phenamil (PM) loaded SF nanoparticles (PMSFNPS) are introduced for treating chronic osteomyelitis. The TEC and PM showed a sustained- and pH-sensitive release behavior from SF/SA hydrogel. The higher release rate was seen in an alkaline pH in comparison to neutral and acidic pH during 10days. The eluted TEC maintained its antibacterial activity of >75% during 35days and in three different pH values (5.5, 7.4, and 8.5). The cellular study indicated that the scaffolds containing PMSFNPs could promote the cell viability, ALP activity, and matrix mineralization. Moreover, the in vivo effectiveness of hydrogel scaffolds were analyzed with radiography, histological and Immunohistochemistry evaluations. The lower infection and higher regeneration were observed in methicillin-resistant Staphylococcus aureus (MRSA) infected rat bone treated with hydrogel scaffold containing PMSFNPs and TEC compared to other groups. Consequently, this dual-drug delivery system could be a hopeful approach for effective treatment of chronic bone infection.

Bone regeneration after marginal bone resection in two-stage treatment of chronic long bone infection - a combined histopathological and clinical pilot study

IntroductionIn chronic bone infection, marginal bone resection avoids large and difficult to reconstruct bone defects. However, there is still a lack of knowledge on bone regeneration during chronic bone infection and bone healing capability after marginal bone resection. Therefore, the purpose of this study was to investigate the clinical and histopathological outcomes after marginal bone resection in chronic long bone infection. We hypothesized that there is a regenerative bone healing potential after marginal bone resection that results in an acceptable clinical outcome and improved pathohistological bone healing parameters during treatment. Materials and methodsNine patients were treated for chronic bone infections in a two-stage manner with marginal bone resection of the infected area and the placement of an antibiotic-loaded polymethyl methacrylate (PMMA) spacer at stage one followed by bone reconstruction at stage two combined with systemic antibiotic therapy. Comparable bone samples were harvested at the border region between vital and necrotic bone area during stage one and the identical location during stage two. Control bone samples were harvested from five healthy patients without bone infection. Clinical outcome in terms of infection eradication and bone consolidation were assessed. The phenotypic changes of osteocyte and morphological changes of lacunar-canalicular network were investigated by histological and immunohistochemical staining between the two observation periods. Furthermore, expression levels of major bone formation and resorption markers were investigated by immunohistochemical and tartrate-resistant acid phosphatase (TRAP) staining. ResultsThe clinical results with a follow-up of 12.9 months showed that eight of nine patients (88.9%) achieved bone consolidation after a planned two-stage procedure of marginal resection of necrotic bone and consecutive reconstruction. In four of the nine patients (44.4%), additional marginal debridements after stage two had to be performed. After marginal resection at stage one, the improved bone formation ability at stage two was demonstrated by significantly lower percentage of empty lacunae, significantly more mature osteocytes and higher BMP-2 positive cell density, whereas decreased resorption was indicated by significantly lower osteoclast density and RANKL/OPG ratio. In patients requiring additional debridement compared to patients without additional debridements, a significantly higher percentage of empty lacunae was found at stage one. ConclusionMarginal bone resection combined with local and systemic antibiotic therapy is a feasible treatment option to avoid large bone defects as bone from the marginal resection area seems to have good regenerative potential. Despite a high revision rate of 44.4%, this technique avoids large bone resection and revisions can be done by further marginal debridements.

Engineered dual-purpose Ta-doped ZnO/Hydroxyapatite nanocomposites: Antibacterial activity and robust catalyst in MW-Induced synthesis of chromopyrimidines

In this paper, engineered dual-purpose Ta-doped ZnO/Hydroxyapatite nanocomposites (Ta-doped ZnO/HAP NCs) have been fabricated via the green protocol. Besides, the morphology-dependent antibacterial survey of Ta-doped ZnO/HAP NCs on diverse bacteria of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, and Acinetobacter baumannii were performed, for the first time. The optimized nanostructures were appraised for performing Agar disk-diffusion analysis and minimum inhibitory concentration (MIC) against different microorganisms. Interestingly, the experimental data displayed that fabricated Ta-doped ZnO/HAP NCs have superior antibacterial activity against Enterococcus faecalis and Staphylococcus aureus. For Ta-doped ZnO/HAP NCs, the Agar disk-diffusion strategy demonstrates that the highest growth inhibition zone was related to Staphylococcus aureus (21 mm). Based on these benefits, Ta-doped ZnO/HAP NCs have been widely investigated as a promising material for developing antibacterial materials for the treatment of chronic implant-related bone infections. Also, antibacterial activity and catalytic performance of engineered dual-purpose Ta-doped ZnO/HAP NCs were examined and its morphology represented to be in the order: flower > rod > sphere > cubic. The flower one could expose more accessible active sites. Also, the novel proposed Ta-doped ZnO/HAP NCs was applied as a robust heterogeneous catalyst for microwave-assisted (MW-assisted) preparation of chromopyrimidines. The obtained products were prepared within the short reaction times (10–17 min) in excellent yields (87–97%).

Diagnostic stewardship based on patient profiles: differential approaches in acute versus chronic infectious syndromes

ABSTRACT Introduction: New diagnostics may be useful in clinical practice, especially in contexts of high prevalence of multidrug-resistant organisms (MDRO). However, misuse of diagnostic tools may lead to increased costs and worse patient outcome. Conventional and new techniques should be appropriately positioned in diagnostic algorithms to guide an appropriate use of antimicrobial therapy. Areas covered: A panel of experts identified 4 main areas in which the implementation of diagnostic stewardship is needed. Among chronic infections, bone and prosthetic joint infections and subacute-chronic intravascular infections and endocarditis represent common challenges for clinicians. Among acute infections, bloodstream infections and community-acquired pneumonia may be associated with high mortality and require appropriate diagnostic approach. Expert opinion: Diagnostic stewardship aims to improve the appropriate use of microbiological diagnostics to guide therapeutic decisions through appropriate and timely diagnostic testing. Here, diagnostic algorithms based on different patient profiles are proposed for chronic and acute clinical syndromes. In each clinical scenario, combining conventional and new diagnostic techniques is crucial to make a rapid and accurate diagnosis and to guide the selection of antimicrobial therapy. Barriers related to the implementation of new rapid diagnostic tools, such as high initial costs, may be overcome through their rational and structured use.

Does local implantation of gentamicin impair renal function in patients undergoing surgery for chronic bone infection?

<p><strong>Background: </strong>The treatment of chronic bone infection often involves excision of dead bone and implantation of biomaterials which elute antibiotics. Gentamicin is a preferred drug for local delivery, but its systemic use carries a well-established risk of nephrotoxicity. We aim to establish the risk of acute kidney injury (AKI) with local delivery in a ceramic carrier.</p><p><strong>Methods: </strong>163 patients with Cierny-Mader type 3 or 4 chronic osteomyelitis had a single-stage operation including filling of the osseous defect with a calcium sulphate-hydroxyapatite carrier containing gentamicin. Mean gentamicin dosing was 191.3 mg (maximum 525 mg). Glomerular filtration rate (GFR) was calculated pre-operatively and during the first seven days post-operatively. Renal impairment was graded using the chronic kidney disease (CKD) staging system, and AKI was assessed using the RIFLE criteria.</p><p><strong>Results: </strong>155 cases had adequate data to allow calculation of pre- and post-operative GFR. 7 had pre-existing renal disease. 70 patients (45.2%) had a temporary GFR drop post-operatively, with the greatest decrease occurring at a mean of 3.06 days following surgery. Twenty cases had a >10% decline in GFR, but 12 resolved within 7 days. 7 patients transiently fell into the “Risk” category according to RIFLE criteria, but no patient had a change consistent with “Injury”, “Failure” or “Loss” of renal function and none had clinical signs of new acute renal impairment post-operatively. </p><p><strong>Conclusions: </strong>Renal function is not significantly affected by local implantation of gentamicin up to 525 mg. The presence of pre-existing renal disease is not a contraindication to local gentamicin therapy.</p><p><strong> </strong></p>