Systemic antimicrobial therapy in osteomyelitis

The Influence of Surface Damage on Miniplates: A Study of Bacterial Attachment Across Various Strains

Background

Postoperative infection and rejection of miniplates in maxillofacial surgery are linked to surface irregularities and bacterial adhesion. This study investigated the physical and microbiological characteristics of patient-rejected miniplates to elucidate factors contributing to implant failure.

Methods

Forty miniplates, including straight-type BSSO and L-shaped designs, were collected from patients. Macro photography documented surface deformities. Contact angle measurements assessed surface wettability. Bacterial adhesion for Staphylococcus aureus, Streptococcus mutans, Pseudomonas aeruginosa, and Enterococcus faecalis was quantified via the crystal violet assay. Scanning electron microscopy (SEM) was used to visualize microbial colonization.

Results

Macro images showed visible deformations, especially in the bridge areas of straight-type BSSO plates. Contact angle analysis revealed significantly greater hydrophobicity in rejected plates than controls (mean: 89.6° vs. 72.3°, p < 0.01). Rejected plates demonstrated significantly increased adhesion of S. aureus and S. mutans (p < 0.001), particularly on mandibular plates. P. aeruginosa adhered more to control plates (p < 0.05), while E. faecalis showed no significant difference between groups. SEM confirmed dense bacterial clusters, with S. aureus forming cocci aggregates and S. mutans forming chains, particularly in regions of surface distortion.

Conclusion

Rejected miniplates exhibit increased surface roughness and hydrophobicity, correlating with elevated bacterial adhesion. These findings highlight the need for improved surface design or coating technologies to reduce biofilm formation and enhance clinical outcomes in maxillofacial surgery.

A comprehensive review of pathology and treatment of staphylococcus aureus osteomyelitis

Osteomyelitis (OM) is an inflammation of the bone and bone marrow triggered by infectious pathogens which may induce progressive bone destruction. The majority of OM cases, especially the chronic OM cases, are induced by the most prevalent and devastating pathogen Staphylococcus aureus (S. aureus), partially due to its resistance mechanisms against the immune system and antibiotic therapies. Regarding the high rate of morbidity and recurrence in patients, it is pivotal to elucidate underlying mechanisms that how S. aureus enter and survive in hosts. The accumulated discoveries have identified multiple distinct strategies associated with chronicity and recurrence include biofilm development, small colony variants (SCVs), staphylococcus abscess communities (SACs), the osteocyte lacuno-canalicular network invasion (OLCN) of cortical bones, and S. aureus protein A (SpA). Unfortunately, little clinical progress has been achieved for the diagnosis and therapeutic treatment for OM patients, indicating that numerous questions remain to be solved. Therefore, we still have a long way to obtain the clear elucidation of the host-pathogen interactions which could be applied for clinical treatment of OM. In this review, we provide insights of current knowledge about how S. aureus evades immune eradication and remains persistent in hosts with recent discoveries. The common and novel treatment strategies for OM are also described. The purpose of this review is to have in-dept understanding of S. aureus OM and bring new perspectives to therapeutic fields which may be translated to the clinic.

Mitigating Risk of Acute Kidney Injury Among Children With Methicillin-resistant Staphylococcus aureus Osteomyelitis

OBJECTIVE

Children with acute hematogenous osteomyelitis (AHO) from methicillin-resistant Staphylococcus aureus (MRSA) are treated with vancomycin despite the risk of acute kidney injury (AKI). This study evaluates the rate of AKI and resource utilization for children with or without AKI when vancomycin is used in this setting.

METHODS

Children with MRSA AHO treated with vancomycin were retrospectively studied. AKI was assessed by clinical diagnosis and Kidney Disease Improving Global Outcomes (KDIGO) criteria. Cohorts of children with or without AKI were compared for differences in treatment, resource utilization, and outcomes. Multivariate logistic regression analysis assessed factors associated with risk for AKI. Cost analysis was performed using the Pediatric Health Information System and Healthcare Cost and Utilization Project databases.

RESULTS

Among 85 children studied, 14 (16.5%) had chart-diagnosed AKI and 24 (28.2%) met KDIGO criteria. Children with AKI had more febrile days and higher thrombosis rates. They had longer vancomycin treatment (8 vs 5 d), higher troughs (27.8 vs 17.5 mg/L), and prolonged hospitalization (19.9 vs 11.1 d). Multivariate analysis found a maximum vancomycin trough level (odds ratio: 1.05, P = 0.003) with a cutoff of 21.7 mg/L predicted AKI.Only 2 of 20 (10%) children who had MRSA isolates with a minimum inhibitory concentration of 2 achieved therapeutic vancomycin levels. Pediatric Health Information System data of 3133 children with AHO treated with vancomycin identified 75 (2.4%) with AKI who had significantly longer lengths of stay (13 vs 7 d) and higher billed charges ($117K vs $51K) than children without AKI.

CONCLUSIONS

Chart documentation of AKI (16.5%) grossly underestimated KDIGO-defined occurrence (28.2%). This study showed that vancomycin-associated AKI required substantially greater resource utilization and higher health care costs. Lowering the targeted trough range, shortening the duration of vancomycin therapy, and considering alternative antibiotics when minimum inhibitory concentration ≥2 will reduce the risk and cost of AKI among children with MRSA AHO.

LEVEL OF EVIDENCE

Level III-retrospective comparative therapeutic study.

Antibiotic-eluting scaffolds with responsive dual-release kinetics facilitate bone healing and eliminate S. aureus infection

Osteomyelitis (OM) is a progressive, inflammatory infection of bone caused predominately by Staphylococcus aureus. Herein, we engineered an antibiotic-eluting collagen-hydroxyapatite scaffold capable of eliminating infection and facilitating bone healing. An iterative freeze-drying and chemical crosslinking approach was leveraged to modify antibiotic release kinetics, resulting in a layered dual-release system whereby an initial rapid release of antibiotic to clear infection was followed by a sustained controlled release to prevent reoccurrence of infection. We observed that the presence of microbial collagenase accelerated antibiotic release from the crosslinked layer of the scaffold, indicating that the material is responsive to microbial activity. As exemplar drugs, vancomycin and gentamicin-eluting scaffolds were demonstrated to be bactericidal, and supported osteogenesis in vitro. In a pilot murine model of OM, vancomycin-eluting scaffolds were observed to reduce S. aureus infection within the tibia. Finally, in a rabbit model of chronic OM, gentamicin-eluting scaffolds both facilitated radial bone defect healing and eliminated S. aureus infection. These results show that antibiotic-eluting collagen-hydroxyapatite scaffolds are a one-stage therapy for OM, which when implanted into infected bone defects simultaneously eradicate infection and facilitate bone tissue healing.

A Bacterial Capturing, Neural Network-Like Carbon Nanotubes/Prussian Blue/Puerarin Nanocomposite for Microwave Treatment of Staphylococcus Aureus-Infected Osteomyelitis

Staphylococcus aureus (S. aureus)-infected osteomyelitis is a deep tissue infection that cannot be effectively treated with antibiotics. Microwave (MW) thermal therapy (MTT) and MW dynamic therapy (MDT) based on MW-responsive materials are promising for the therapy of bacteria-infected osteomyelitis occurring in deep tissues that cannot be effectively treated with antibiotics. In this work, the MW-responsive system of carbon nanotubes (CNTs)/Prussian blue (PB)/puerarin (Pue) with stable network-like structures is constructed. The PB is grown in situ on the CNTs, and its introduction not only reduces the aggregation of the network-like structures of the CNTs, but the large specific surface area and mesoporous structure can also provide many active sites for the adsorption of oxygen and polar molecules. Pue is a natural anti-inflammatory material that reduces inflammation at the infection site. The composite of the CNTs and PB avoids the skin effect and thus can improve dielectric and reflection losses. The MW thermal response of CNTs/PB/Pue is mainly due to the occurrence of reflection loss, dielectric loss, multiple reflections and scattering, interface polarization, and dipole polarization. In addition, under MW irradiation, the CNTs/PB/Pue can produce reactive oxygen species (ROS), such as singlet oxygen (1O2), hydroxyl radical (·OH).

Interface/Dipole Polarized Antibiotics-Loaded Fe3O4/PB Nanoparticles for Non-Invasive Therapy of Osteomyelitis Under Medical Microwave Irradiation

Due to their poor light penetration, photothermal therapy and photodynamic therapy are ineffective in treating deep tissue infections, such as osteomyelitis caused by Staphylococcus aureus (S. aureus). Here, a microwave (MW)-responsive magnetic targeting composite system consisting of ferric oxide (Fe3O4)/Prussian blue (PB) nanoparticles, gentamicin (Gent), and biodegradable poly(lactic-co-glycolic acid) (PLGA) is reported. The PLGA/Fe3O4/PB/Gent complex is used in combination with MW thermal therapy (MTT), MW dynamic therapy (MDT), and chemotherapy (CT) to treat acute osteomyelitis infected with S. aureus-infected. The powerful antibacterial effect of the PLGA/Fe3O4/PB/Gent is determined by the synergistic effects of heat and reactive oxygen species (ROS) generation by the Fe3O4/PB nanoparticles under MW irradiation and the effective release of Gent at the infection site via magnetic targeting. The antibacterial mechanism of the PLGA/Fe3O4/PB/Gent under MW irradiation is analyzed using bacterial transcriptome RNA sequencing. The MW heat and ROS reduce the activity of the protein transporters on the bacterial membrane, along with the transport of various ions and the acceleration of phosphate metabolism, which can lead to increased permeability of the bacterial membrane, damage the ribosome and DNA, and accompany the internal protein efflux of the bacteria, thus effectively killing the bacteria.

Anti-Microbial Drug Metronidazole Promotes Fracture Healing: Enhancement in the Bone Regenerative Efficacy of the Drug by a Biodegradable Sustained-Release In Situ Gel Formulation

Nitroimidazoles comprise a class of broad-spectrum anti-microbial drugs with efficacy against parasites, mycobacteria, and anaerobic Gram-positive and Gram-negative bacteria. Among these drugs, metronidazole (MTZ) is commonly used with other antibiotics to prevent infection in open fractures. However, the effect of MTZ on bone remains understudied. In this paper, we evaluated six nitroimidazole drugs for their impact on osteoblast differentiation and identified MTZ as having the highest osteogenic effect. MTZ enhanced bone regeneration at the femur osteotomy site in osteopenic ovariectomized (OVX) rats at the human equivalent dose. Moreover, in OVX rats, MTZ significantly improved bone mass and strength and improved microarchitecture compared to the vehicle-treated rats, which was likely achieved by an osteogenic mechanism attributed to the stimulation of the Wnt pathway in osteoblasts. To mitigate the reported neurological and genotoxic effects of MTZ, we designed an injectable sustained-release in situ gel formulation of the drug that improved fracture healing efficacy by 3.5-fold compared to oral administration. This enhanced potency was achieved through a significant increase in the circulating half-life and bioavailability of MTZ. We conclude that MTZ exhibits osteogenic effects, further accentuated by our sustained-release delivery system, which holds promise for enhancing bone regeneration in open fractures.

Diagnostic efficacy and clinical impact of image-guided core needle biopsy of suspected vertebral osteomyelitis

OBJECTIVES

The diagnostic yield and clinical impact of image-guided core needle biopsy (ICNB) of suspected vertebral osteomyelitis in adults is heterogenous in published studies owing to small sample sizes, indicating the need for large cohort studies.

METHODS

A retrospective analysis of ICNBs was performed from 2010 to 2021 for patients with imaging findings consistent with vertebral osteomyelitis. For each biopsy, a series of factors were analyzed, as well as if histopathology was diagnostic of osteomyelitis and if microbiological cultures were positive. In addition, it was recorded in what way biopsy influenced clinical management regarding antimicrobial treatment. A multivariate statistical analysis was performed to evaluate the factors associated with yield.

RESULTS

A total of 570 biopsies performed on 527 patients were included. A histopathologic diagnosis of osteomyelitis was made in 68.4% (359 of 525) of biopsies, and microbiological cultures were positive in 29.6% (169 of 570). Elevated erythrocyte sedimentation rate was positively associated with a histopathologic diagnosis of osteomyelitis (odds ratio [OR] =1.96, P = 0.007) and positive cultures from bone cores (OR = 1.02, P ≤0.001) and aspirate (OR = 1.02, P ≤0.001). Increased total core length was positively associated with a histopathologic diagnosis of osteomyelitis (OR = 1.81, P = 0.013) and positive cultures from bone cores (OR = 1.65, P = 0.049). Clinical management was affected by ICNB in 37.5% (214 of 570) of cases.

CONCLUSIONS

In this large cohort, ICNB yielded approximately 30% positive cultures and changed clinical management in over one-third of the patients.

Dual release of daptomycin and BMP-2 from a composite of β-TCP ceramic and ADA gelatin

BACKGROUND

Antibiotic-containing carrier systems are one option that offers the advantage of releasing active ingredients over a longer period of time. In vitro sustained drug release from a carrier system consisting of microporous β-TCP ceramic and alginate has been reported in previous works. Alginate dialdehyde (ADA) gelatin gel showed both better mechanical properties when loaded into a β-TCP ceramic and higher biodegradability than pure alginate.

METHODS

Dual release of daptomycin and BMP-2 was measured on days 1, 2, 3, 6, 9, 14, 21, and 28 by HPLC and ELISA. After release, the microbial efficacy of the daptomycin was verified and the biocompatibility of the composite was tested in cell culture.

RESULTS

Daptomycin and the model compound FITC protein A (n = 30) were released from the composite over 28 days. A Daptomycin release above the minimum inhibitory concentration (MIC) by day 9 and a burst release of 71.7 ± 5.9% were observed in the loaded ceramics. Low concentrations of BMP-2 were released from the loaded ceramics over 28 days.

Systemic application of bone-targeting peptidoglycan hydrolases as a novel treatment approach for staphylococcal bone infection

IMPORTANCE

The rising prevalence of antimicrobial resistance in S. aureus has rendered treatment of staphylococcal infections increasingly difficult, making the discovery of alternative treatment options a high priority. Peptidoglycan hydrolases, a diverse group of bacteriolytic enzymes, show high promise as such alternatives due to their rapid and specific lysis of bacterial cells, independent of antibiotic resistance profiles. However, using these enzymes for the systemic treatment of local infections, such as osteomyelitis foci, needs improvement, as the therapeutic distributes throughout the whole host, resulting in low concentrations at the actual infection site. In addition, the occurrence of intracellularly persisting bacteria can lead to relapsing infections. Here, we describe an approach using tissue-targeting to increase the local concentration of therapeutic enzymes in the infected bone. The enzymes were modified with a short targeting moiety that mediated accumulation of the therapeutic in osteoblasts and additionally enables targeting of intracellularly surviving bacteria.

Osteosynthesis-associated infection in maxillofacial surgery by bacterial biofilms: a retrospective cohort study of 11 years

OBJECTIVES

The aim of this retrospective cohort study was to determine risk factors for osteosynthesis-associated infections (OAI) with subsequent necessity of implant removal in oral and maxillofacial surgery.

MATERIALS AND METHODS

A total of 3937 records of patients who received either orthognathic, trauma, or reconstructive jaw surgery from 2009 to 2021 were screened for osteosynthetic material removal due to infection. Treatment-intervals, volume of applied osteosynthetic material, and respective surgical procedures were also assessed. Moreover, intraoperatively harvested microbial flora was cultured and subsequently identified by MALDI TOF. Bacteria were then screened for antibiotic resistance via VITEK system or, if necessary, via agar diffusion or epsilometer test. Data was analyzed utilizing SPSS statistical software. For statistical analysis of categorical variables, chi-square tests or Fisher exact tests were used. Continuous variables were compared via non-parametric tests. The level of significance for p-values was set at < 0.05. Descriptive analysis was also performed.

RESULTS

The lower jaw was more prone to OAI than the mid face region. Larger volumes of osteosynthetic material led to significantly more OAI, resulting in reconstruction plates bearing the highest risk for OAI especially when compared to small-volume mini-plates frequently applied in trauma surgery. Among OAI associated with implant volumes smaller than 1500 mm3, the detection of Streptococcus spp., Prevotella spp., Staphylococcus spp., and Veillonella spp. was significantly elevated, whereas implant volumes larger than 1500 mm3 showed a significant increase of Enterococcus faecalis, Proteus mirabilis and Pseudomonas aeruginosa. High susceptibility rates (87.7-95.7%) were documented for 2nd- and 3rd-generation cephalosporines and piperacillin/tazobactam.

CONCLUSION

High material load and lower jaw reconstruction bear the greatest risks for OAI. When working with large volume osteosynthetic implants, gram-negative pathogens must be considered when choosing an appropriate antibiotic regime. Suitable antibiotics include, e.g., piperacillin/tazobactam and 3rd-generation cephalosporines.

CLINICAL RELEVANCE

Osteosynthetic material utilized in reconstructive procedures of the lower jaw may be colonized with drug-resistant biofilms.

Pyogenic spondylitis caused by Escherichia coli: A case report and literature review

BACKGROUND

Pyogenic spondylitis is often manifested as atypical low back pain and fever, which makes it easy to be confused with other diseases. Here we report a case of pyogenic spondylitis and describe the diagnosis and treatment based on the related literature.

CASE SUMMARY

The reported case suffered from pyogenic spondylitis caused by Escherichia coli and complicated with bacteremia and psoas abscess. Acute pyelonephritis was initially diagnosed due to atypical symptoms. Symptoms were improved from antibiotic treatment while developing progressive lower limb dysfunction. One month post the admission, the patient underwent anterior lumbar debridement + autogenous iliac bone graft fusion + posterior percutaneous screw-rod internal fixation, and received 6 wk of antibiotic treatment after the operation. Reexamination 4 mo post the operation showed that the patient had no evident pain in the waist, and walked well with no evident dysfunction of lower limbs.

CONCLUSION

Here we describe the application value of several imaging examinations, such as X-ray, computed tomography and magnetic resonance imaging, and certain tests like erythrocyte sedimentation rate and C-reactive protein in the clinical treatment of pyogenic spondylitis. This disease requires early diagnosis and treatment. Sensitive antibiotics should be used in early stages and surgical intervention should be taken if necessary, which may help for a speedy recovery and prevent the occurrence of severe complications.

Encountering pelvic tuberculosis in closed pelvic ring injury with distant wound - An intraoperative surprise: A case report

Delayed presentation of closed APC type III pelvic ring injury with a healing wound on the medial thigh, in a twenty-six-year-old male, at four weeks. We planned Symphyseal plating and sacroiliac screw fixation surgery. After percutaneous screw fixation, subsequent pelvic exposure revealed whitish cheesy pus in the retropubic space. Hence, we changed surgery from internal fixation to a supra-acetabular external fixator. Subsequent molecular testing documented tuberculosis and regimen of antitubercular medications was started. Complete functional recovery was observed at 12 months. While managing pelvic injuries, alternative backup treatment plans should be kept ready in view of infective foci.

Identification of Ferroptosis-Related Biomarkers for Diagnosis and Molecular Classification of Staphylococcus aureus-Induced Osteomyelitis

Objective

Staphylococcus aureus (SA)-induced osteomyelitis (OM) is one of the most common refractory diseases in orthopedics. Early diagnosis is beneficial to improve the prognosis of patients. Ferroptosis plays a key role in inflammation and immune response, while the mechanism of ferroptosis-related genes (FRGs) in SA-induced OM is still unclear. The purpose of this study was to determine the role of ferroptosis-related genes in the diagnosis, molecular classification and immune infiltration of SA-induced OM by bioinformatics.

Methods

Datasets related to SA-induced OM and ferroptosis were collected from the Gene Expression Omnibus (GEO) and ferroptosis databases, respectively. The least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE) algorithms were combined to screen out differentially expressed-FRGs (DE-FRGs) with diagnostic characteristics, and gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used to explore specific biological functions and pathways. Based on these key DE-FRGs, a diagnostic model was established, and molecular subtypes were divided to explore the changes in the immune microenvironment between molecular subtypes.

Results

A total of 41 DE-FRGs were identified. After screening and intersecting with LASSO and SVM-RFE algorithms, 8 key DE-FRGs with diagnostic characteristics were obtained, which may regulate the pathogenesis of OM through the immune response and amino acid metabolism. The ROC curve indicated that the 8 DE-FRGs had excellent diagnostic ability for SA-induced OM (AUC=0.993). Two different molecular subtypes (subtype 1 and subtype 2) were identified by unsupervised cluster analysis. The CIBERSORT analysis revealed that the subtype 1 OM had higher immune cell infiltration rates, mainly in T cells CD4 memory resting, macrophages M0, macrophages M2, dendritic cells resting, and dendritic cells activated.

Conclusion

We developed a diagnostic model related to ferroptosis and molecular subtypes significantly related to immune infiltration, which may provide a novel insight for exploring the pathogenesis and immunotherapy of SA-induced OM.

Review on skeletal disorders caused by Staphylococcus spp. in poultry

Lameness or leg weakness is the main cause of poor poultry welfare and serious economic losses in meat-type poultry production worldwide. Disorders related to the legs are often associated with multifactorial aetiology which makes diagnosis and proper treatment difficult. Among the infectious agents, bacteria of genus Staphylococcus are one of the most common causes of bone infections in poultry and are some of the oldest bacterial infections described in poultry. Staphylococci readily infect bones and joints and are associated with bacterial chondronecrosis with osteomyelitis (BCO), spondylitis, arthritis, tendinitis, tenosynovitis, osteomyelitis, turkey osteomyelitis complex (TOC), bumblefoot, dyschondroplasia with osteomyelitis and amyloid arthropathy. Overall, 61 staphylococcal species have been described so far, and 56% of them (34/61) have been isolated from clinical cases in poultry. Although Staphylococcus aureus is the principal cause of poultry staphylococcosis, other Staphylococcus species, such as S. agnetis, S. cohnii, S. epidermidis, S. hyicus, S. simulans, have also been isolated from skeletal lesions. Antimicrobial treatment of staphylococcosis is usually ineffective due to the location and type of lesion, as well as the possible occurrence of multidrug-resistant strains. Increasing demand for antibiotic-free farming has contributed to the use of alternatives to antibiotics. Other prevention methods, such as better management strategies, early feed restriction or use of slow growing broilers should be implemented to avoid rapid growth rate, which is associated with locomotor problems. This review aims to summarise and address current knowledge on skeletal disorders associated with Staphylococcus spp. infection in poultry.

Diabetic Foot Infections: Bacterial Isolates From the Centers and Hospitals of Latin American Countries

Diabetic foot infections (DFIs) are one of the most important reasons for lower limb amputations. An adequate approach to the management of DFI implies control of infection using strategies of tissue debridement and empirical antibiotic treatment based on local microbiology. The aim of this study was to determine the bacterial isolates profile and antibiotic susceptibility patterns in samples from DFI from Latin American centers, on the premise that microbiology of this region differs from that of other continents and influences antimicrobial election. Three hundred and eighty-two samples from soft tissue and bone were studied from 17 centers of 4 countries. Three hundred and seven (80.4%; 95% confidence interval = 75.9-84.2) were positive. Gram negatives (GN) were isolated in 43.8% of all samples, not only in severe but also in mild infections, 51% in bone samples, more frequently in presence of ischemia (47% vs 38%; P = .07) and in wounds with longer duration of the lesion (30-20 days; P < .01). Staphylococcus aureus was the most frequent single germ (19.9%). Gram positives were isolated more frequently in patients without ischemia (53% vs 40%; P = .01). Enterococcus faecalis was the most frequent germ in bone samples (16.8%). Ciprofloxacin and trimethoprim-sulfamethoxazole were the oral antimicrobials most effective against GN. Trimethoprim-sulfamethoxazole and rifampicin were the oral antimicrobials most effective against Staphylococcus. Because of GN high antibiotic resistance patterns, patients treated in an ambulatory setting have to be controlled early after starting empiric treatment to assess response to therapy and hospitalize for parenteral antibiotics if oral treatment fails.

Minimal invasiveness in the reconstructive treatment of peri-implantitis defects

Peri-implantitis is a plaque-associated pathologic condition occurring in tissues around dental implants, clinically characterized by increased peri-implant probing pocket depth and progressive loss of supporting bone. Consequently, to arrest further disease progression and to increase the chance to obtain re-osseointegration, surgical reconstructive procedures have been adopted. In particular, following a paradigm gathered from periodontal therapy, recent protocols have underlined the importance of a minimally invasive approach to optimize the outcomes of therapy while minimizing the risks of postoperative complications. The present review summarizes the level of evidence on the surgical reconstructive protocols focusing on the new approaches aiming to minimize surgical trauma and patients' postoperative discomfort, underlining the pros and cons of each treatment modality.

Strategies to Improve the Potency of Oxazolidinones towards Bacterial Biofilms

Biofilms are part of the natural lifecycle of bacteria and are known to cause chronic infections that are difficult to treat. Most antibiotics are developed and tested against bacteria in the planktonic state and are ineffective against bacterial biofilms. The oxazolidinones, including the last resort drug linezolid, are one of the main classes of synthetic antibiotics progressed to clinical use in the last 50 years. They have a unique mechanism of action and only develop low levels of resistance in the clinical setting. With the aim of providing insight into strategies to design more potent antibiotic compounds with activity against bacterial biofilms, we review the biofilm activity of clinically approved oxazolidinones and report on structural modifications to oxazolidinones and their delivery systems which lead to enhanced anti-biofilm activity.

The Fate of Antibiotic Impregnated Cement Space in Treatment for Forefoot Osteomyelitis

Forefoot osteomyelitis can be an extremely challenging problem in orthopedic surgery. Unlike conventional methods, such as amputations, antibiotic impregnated cement space (ACS) was recently introduced and perceived as a substitute for amputation. The purpose of this study was to compare clinical features between diabetic and non-diabetic groups and to evaluate the efficacy of ACS in the treatment of forefoot osteomyelitis, by identifying the clinical characteristics of ACS. We inserted ACS into the forefoot osteomyelitis patients and regularly checked up on them, then analyzed the clinical features of the patients and failure reasons, if ACS had to be removed. Average survival rate of ACS was 60% (21 out of 35 cases) and main failure reason was recurrence of infection. There was no significant clinical difference between diabetic and non-diabetic groups. We concluded that ACS could be a possible way of avoiding amputation if infection is under control. ACS seems to be an innovative method with promising results for foot osteomyelitis, but widely accepted indications need to be agreed upon.

A New Treatment Algorithm That Incorporates Minimally Invasive Surgery for Pyogenic Spondylodiscitis in the Thoracic and Lumbar Spines: The Results of Its Clinical Application to a Series of 34 Patients

Background and Objectives: Spinal minimally invasive surgery (MIS) experts at the university hospital worked as a team to develop a new treatment algorithm for pyogenic spondylodiscitis in lumbar and thoracic spines. They modified a flow chart introduced for this condition in a pre-MIS era to incorporate MIS techniques based on their extensive experiences accumulated over the years, both in MIS for degenerative lumbar diseases and in the treatment of spine infections. The MIS procedures incorporated in this algorithm consisted of percutaneous pedicle screw (PPS)–rod fixation and transpsoas lateral lumbar interbody fusion (LLIF). The current study analyzed a series of 34 patients treated with prospective selection of the methods according to this new algorithm. Materials and Methods: The algorithm first divided the patients into those who had escaped complicated disease conditions, such as neurologic impairment, extensive bone destruction, and the need to be mobilized without delay (Group 1) (19), and those with complicated pyogenic spondylodiscitis (Group 2) (15). Group 1 had image-guided needle biopsy followed by conservative treatment alone with antibiotics and a spinal brace (12) (Group 1-A) or a subsequent addition of non-fused PPS–rod fixation (7) (Group 1-B). Group 2 underwent an immediate single-stage MIS with non-fused PPS–rod fixation followed by posterior exposure for decompression and debridement through a small midline incision (12) (Group 2-A) or an additional LLIF procedure after an interval of 3 weeks (3) (Group 2-B). Results: All patients, except four, who either died from causes unrelated to the spondylodiscitis (2) or became lost to follow up (2), were cured of infection with normalized CRP at an average follow up of 606 days (105–1522 days). A solid interbody fusion occurred at the affected vertebrae in 15 patients (50%). Of the patients in Group 2, all but two regained a nearly normal function. Despite concerns about non-fused PPS–rod instrumentation, only seven patients (21%) required implant removal or replacement. Conclusions: Non-fused PPS–rod placements into infection-free vertebrae alone or in combination with posterior debridement through a small incision worked effectively in providing local stabilization without contamination of the metal implant from the infected tissue. MIS LLIF allowed for direct access to the infected focus for bone grafting in cases of extensive vertebral body destruction.

A multifunctional micropore-forming bioink with enhanced anti-bacterial and anti-inflammatory properties

Three-dimensional (3D) bioprinting has emerged as an enabling tool for various biomedical applications, such as tissue regeneration and tissue model engineering. To this end, the development of bioinks with multiple functions plays a crucial role in the applications of 3D bioprinting technologies. In this study, we propose a new bioink based on two immiscible aqueous phases of gelatin methacryloyl (GelMA) and dextran, further endowed with anti-bacterial and anti-inflammatory properties. This micropore-forming GelMA-dextran (PGelDex) bioink exhibited excellent printability with vat-polymerization, extrusion, and handheld bioprinting methods. The porous structure was confirmed after bioprinting, which promoted the spreading of the encapsulated cells, exhibiting the exceptional cytocompatibility of this bioink formulation. To extend the applications of such a micropore-forming bioink, interleukin-4 (IL-4)-loaded silver-coated gold nanorods (AgGNRs) and human mesenchymal stem cells (MSCs) were simultaneously incorporated, to display synergistic anti-infection behavior and immunomodulatory function. The results revealed the anti-bacterial properties of the AgGNR-loaded PGelDex bioink for both Gram-negative and Gram-positive bacteria. The data also indicated that the presence of IL-4 and MSCs facilitated macrophage M2-phenotype differentiation, suggesting the potential anti-inflammatory feature of the bioink. Overall, this unique anti-bacterial and immunomodulatory micropore-forming bioink offers an effective strategy for the inhibition of bacterial-induced infections as well as the ability of immune-regulation, which is a promising candidate for broadened tissue bioprinting applications.

Recent advances in the local antibiotics delivery systems for management of osteomyelitis

Chronic osteomyelitis is a challenging disease due to its serious rates of mortality and morbidity while the currently available treatment strategies are suboptimal. In contrast to the adopted systemic treatment approaches after surgical debridement in chronic osteomyelitis, local drug delivery systems are receiving great attention in the recent decades. Local drug delivery systems using special carriers have the pros of enhancing the feasibility of penetration of antimicrobial agents to bone tissues, providing sustained release and localized concentrations of the antimicrobial agents in the infected area while avoiding the systemic side effects and toxicity. Most important, the incorporation of osteoinductive and osteoconductive materials in these systems assists bones proliferation and differentiation, hence the generation of new bone materials is enhanced. Some of these systems can also provide mechanical support for the long bones during the healing process. Most important, if the local systems are designed to be injectable to the affected site and biodegradable, they will reduce the level of invasion required for implantation and can win the patients’ compliance and reduce the healing period. They will also allow multiple injections during the course of therapy to guard against the side effect of the long-term systemic therapy. The current review presents different available approaches for delivering antimicrobial agents for the treatment of osteomyelitis focusing on the recent advances in researches for local delivery of antibiotics.

HIGHLIGHTS

Chronic osteomyelitis is a challenging disease due to its serious mortality and morbidity rates and limited effective treatment options.

Local drug delivery systems are receiving great attention in the recent decades.

Osteoinductive and osteoconductive materials in the local systems assists bones proliferation and differentiation

Local systems can be designed to provide mechanical support for the long bones during the healing process.

Designing the local system to be injectable to the affected site and biodegradable will reduces the level of invasion and win the patients’ compliance.

Comparative efficacy of resorbable fiber wraps loaded with gentamicin sulfate or gallium maltolate in the treatment of osteomyelitis

The high incidence of osteomyelitis associated with critical-sized bone defects raises clinical challenges in fracture healing. Clinical use of antibiotic-loaded bone cement as an adjunct therapy is limited by incompatibility with many antimicrobials, sub-optimal release kinetics, and requirement of surgical removal. Furthermore, overuse of antibiotics can lead to bacterial modifications that increase efflux, decrease binding, or cause inactivation of the antibiotics. Herein, we compared the efficacy of gallium maltolate, a new metal-based antimicrobial, to gentamicin sulfate released from electrospun poly(lactic-co-glycolic) acid (PLGA) wraps in the treatment of osteomyelitis. In vitro evaluation demonstrated sustained release of each antimicrobial up to 14 days. A Kirby Bauer assay indicated that the gentamicin sulfate-loaded wrap inhibited the growth of osteomyelitis-derived isolates, comparable to the gentamicin sulfate powder control. In contrast, the gallium maltolate-loaded wrap did not inhibit bacteria growth. Subsequent microdilution assays indicated a lower than expected sensitivity of the osteomyelitis strain to the gallium maltolate with release concentrations below the threshold for bactericidal activity. A comparison of the selectivity indices indicated that gentamicin sulfate was less toxic and more efficacious than gallium maltolate. A pilot study in a contaminated femoral defect model confirmed that the sustained release of gentamicin sulfate from the electrospun wrap resulted in bacteria density reduction on the surrounding bone, muscle, and hardware below the threshold that impedes healing. Overall, these findings demonstrate the efficacy of a resorbable, antimicrobial wrap that can be used as an adjunct or stand-alone therapy for controlled release of antimicrobials in the treatment of osteomyelitis.

Titania Nanotube Architectures Synthesized on 3D-Printed Ti-6Al-4V Implant and Assessing Vancomycin Release Protocols

The aim of this study is to synthesize Titania nanotubes (TNTs) on the 3D-printed Ti-6Al-4V surface and investigate the loading of antibacterial vancomycin drug dose of 200 ppm for local drug treatment application for 24 h. The antibacterial drug release from synthesized nanotubes evaluated via the chemical surface measurement and the linear fitting of Korsmeyer–Peppas model was also assessed. The TNTs were synthesized on the Ti-6Al-4V surface through the anodization process at different anodization time. The TNTs morphology was characterized using field emission scanning electron microscope (FESEM). The wettability and the chemical composition of the Ti-6Al-4V surface and the TNTs were assessed using the contact angle meter, Fourier transform infrared spectrophotometer (FTIR) and the X-ray photoelectron spectroscopy (XPS). The vancomycin of 200 ppm release behavior under controlled atmosphere was measured by the high-performance liquid chromatography (HPLC) and hence, the position for retention time at 2.5 min was ascertained. The FESEM analysis confirmed the formation of nanostructured TNTs with vertically oriented, closely packed, smooth and unperforated walls. The maximum cumulative vancomycin release of 34.7% (69.5 ppm) was recorded at 24 h. The wetting angle of both Ti-6Al-4V implant and the TNTs were found below 90 degrees. This confirmed their excellent wettability.

Delayed Presentation of Seymour Fractures: A Single Institution Experience and Management Recommendations

Background: Seymour fractures in children are prone to complications without prompt and appropriate treatment. This study investigated outcomes of Seymour fractures with delayed presentations; specifically, if deep infection predisposed to operative treatment, if antibiotic administration improved fracture healing, and if oral clindamycin had fewer treatment failures than oral cephalexin. Methods: A single-institution retrospective cohort study was performed of patients with delayed Seymour fracture presentations (defined as greater than 24 hours post-injury) between 2009 and 2017. Data collected included demographics, time to presentation, infection on presentation, operative treatment, antibiotic use and duration, fracture union, and complications. Statistical testing used logistic regression and Fisher's exact test, with results reported as P-values (P), odds ratios (ORs), and 95% confidence intervals (CIs). Results: There were 73 patients with delayed Seymour fracture presentations, with mean age of 11.1 years (standard deviation: 2.9), with 56 (77%) males, and median time to presentation of 7 days (interquartile range: 3-17). Deep infection on presentation was a risk factor for operative intervention (OR = 34.4, P = .0001, CI, 5.5-217.2). Antibiotic administration protected against the development of a nonunion or delayed union (OR = 0.11, P = .008, CI, 0.021-0.57). Time to antibiotics did not protect against nonunion or delayed union (OR = 0.77, P = .306, CI, 0.37-1.3). Clindamycin had fewer treatment failures than cephalexin (P = .039). Conclusions: Deep infection is a risk factor for operative treatment of Seymour fractures with delayed presentations. Clindamycin is a better antibiotic choice for Seymour fractures that present in delayed fashion.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members.As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Review on Surface Treatment for Implant Infection via Gentamicin and Antibiotic Releasing Coatings

Surface treatment of metallic implants plays a crucial role in orthopedics and orthodontics. Metallic implants produce side-effects such as physical, chemical/electro-chemical irritations, oligodynamic/catalytic and carcinogenic effects. These effects cause bacterial infections and account for huge medical expenses. Treatment for these infections comprises repeated radical debridement, replacement of the implant device and intravenous or oral injection antibiotics. Infection is due to the presence of bacteria in the patient or the surrounding environment. The antibiotic-based medication prevents prophylaxis against bacterial colonization, which is an emphatic method that may otherwise be catastrophic to a patient. Therefore, preventive measures are essential. A coating process was developed with its drug infusion and effect opposing biofilms. Modification in the medical implant surface reduces the adhesion of bacterial and biofilms, the reason behind bacterial attachment. Other polymer-based and nanoparticle-based carriers are used to resolve implant infections. Therefore, using an implant coating is a better approach to prevent infection due to biofilm.

Practical Gram-Scale Synthesis of Iboxamycin, a Potent Antibiotic Candidate

A gram-scale synthesis of iboxamycin, an antibiotic candidate bearing a fused bicyclic amino acid residue, is presented. A pivotal transformation in the route involves an intramolecular hydrosilylation-oxidation sequence to set the ring-fusion stereocenters of the bicyclic scaffold. Other notable features of the synthesis include a high-yielding, highly diastereoselective alkylation of a pseudoephenamine amide, a convergent sp³-sp² Negishi coupling, and a one-pot transacetalization-reduction reaction to form the target compound's oxepane ring. Implementation of this synthetic strategy has provided ample quantities of iboxamycin to allow for its in vivo profiling in murine models of infection.

Bisphosphonates in dentistry: Historical perspectives, adverse effects, and novel applications

Studies of the potential role of bisphosphonates in dentistry date back to physical chemical research in the 1960s, and the genesis of the discovery of bisphosphonate pharmacology in part can be linked to some of this work. Since that time, parallel research on the effects of bisphosphonates on bone metabolism continued, while efforts in the dental field included studies of bisphosphonate effects on dental calculus, caries, and alveolar bone loss. While some utility of this drug class in the dental field was identified, leading to their experimental use in various dentrifice formulations and in some dental applications clinically, adverse effects of bisphosphonates in the jaws have also received attention. Most recently, certain bisphosphonates, particularly those with strong bone targeting properties, but limited biochemical effects (low potency bisphosphonates), are being studied as a local remedy for the concerns of adverse effects associated with other more potent members of this drug class. Additionally, low potency bisphosphonate analogs are under study as vectors to target active drugs to the mineral surfaces of the jawbones. These latter efforts have been devised for the prevention and treatment of oral problems, such as infections associated with oral surgery and implants. Advances in the utility and mechanistic understanding of the bisphosphonate class may enable additional oral therapeutic options for the management of multiple aspects of dental health.

Elution Profiles of Synthetic CaSO4 Hemihydrate Beads Loaded with Vancomycin and Tobramycin

Backgrounds and Objectives

The use of local antibiotic delivery vehicles is common in the management of biofilm-related infections as they provide high concentrations of local antibiotics while simultaneously avoiding complications from systemic toxicity. We present a 100% pure synthetic calcium sulfate hemi-hydrate mixed with 240 mg tobramycin and 500 mg vancomycin per 10 cc mixture for use in revision surgeries of periprosthetic joint infections (PJIs). The purified carrier demonstrates bioabsorbablity, promotion of bone growth, a physiologically favorable pH, and hydrophilicity. These unique properties may alleviate persistent postoperative wound drainage seen in patients with PJI. Our questions consist of two parts: (1) does the novel calcium sulfate carrier provide therapeutic concentrations of antibiotic locally that can kill biofilm related infections? (2) Are serum concentrations of antibiotic significant to cause concern for systemic toxicity?

Methods

To address these questions, we assayed the elution of antibiotic concentrations obtained from surgical drains and serum among 50 patients in the first 5 postoperative days.

Results

The elution of vancomycin and tobramycin was greatest on day 1 compared with those concentrations obtained on days 2, 3, 4, and 5; serum concentrations were largely undetectable. Our findings demonstrate that this calcium sulfate preparation provides therapeutic delivery of vancomycin and tobramycin locally at log 2–3 above the minimum inhibitory concentration (MIC), while avoiding toxic serum concentrations.

Conclusions

When used in one-stage revision arthroplasties, the bioabsorbable, purified carrier delivers high concentrations of antibiotic while avoiding systemic toxicity.

Bisphosphonates for delivering drugs to bone

Advances in the design of potential bone-selective drugs for the treatment of various bone-related diseases are creating exciting new directions for multiple unmet medical needs. For bone-related cancers, off-target/non-bone toxicities with current drugs represent a significant barrier to the quality of life of affected patients. For bone infections and osteomyelitis, bacterial biofilms on infected bones limit the efficacy of antibiotics because it is hard to access the bacteria with current approaches. Promising new experimental approaches to therapy, based on bone-targeting of drugs, have been used in animal models of these conditions and demonstrate improved efficacy and safety. The success of these drug-design strategies bodes well for the development of therapies with improved efficacy for the treatment of diseases affecting the skeleton. LINKED ARTICLES: This article is part of a themed issue on The molecular pharmacology of bone and cancer-related bone diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.9/issuetoc.

Inhibitory properties of Chinese Herbal Formula SanHuang decoction on biofilm formation by antibiotic-resistant Staphylococcal strains

The aim of this study was to explore the effect of Chinese herbal SanHuang decoction (SH) on biofilm formation of antibiotic-resistant Staphylococci on titanium surface, and to explore its mechanism. Biofilm-forming ATCC 35984, ATCC 43300 and MRSE 287 were used in this study. The MICs of SH and vancomycin against Staphylococci were determined by the broth microdilution method. Six groups were designed, namely control group (bacteria cultured with medium), 1/8MIC SH group (1MIC SH was diluted by 1/8 using TSB or saline), 1/4MIC SH group, 1/2MIC SH group, 1MIC SH group and vancomycin group (bacteria cultured with 1MIC vancomycin). The inhibitory effect on bacterial adhesion and biofilm formation were observed by the spread plate method, CV staining, SEM, and CLSM. Real-time PCR was performed to determine the effect of SH on the expression levels of ica AD and ica R gene in ATCC 35984 during the biofilm formation. The strains were found to be susceptible to SH and vancomycin with MIC of 38.75 mg/ml and 2.5 μg/ml, respectively. SH with 1 MIC and 1/2 MIC could inhibit the bacteria adhesion, showing only scattered adhesion from SEM. CLSM showed that SH with 1 MIC and 1/2 MIC inhibited the biofilm formation. The quantitative results of the spread plate method and CV staining showed that there was significant differences between the SH groups (P < 0.05). Further, with an increase in SH concentration, the inhibitory effect became more obvious when compared with control group. Among the groups, vancomycin had the strongest inhibitory effect on bacterial adhesion and biofilm formation (P < 0.01). With an increase in SH concentration, the expression levels of ica AD decreased, and the expression of ica R increased correspondingly (P < 0.05). In conclusions, SH can inhibit the biofilm formation of antibiotic-resistant Staphylococci. Its probable mechanistic activity may be through the inhibition of polysaccharide intercellular adhesin synthesis by down-regulating the expression of ica AD gene.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Concentration of Penicillin G in Jawbone Affected by Antiresorptive Agent-Related Osteonecrosis Following a Single Preoperative Dose

The aim of this study was to evaluate the concentration of penicillin G in bone affected by antiresorptive agent-related osteonecrosis of the jaw (ARONJ) following a single preoperative dose of 10 million international units (6000 mg). ARONJ is a major concern in patients administered antiresorptive agents for conditions associated with pathologically increased bone resorption. Antibiotic therapy is a key component of most treatment approaches for ARONJ and penicillin based regimens, providing a cost effective therapy option with a favorable side effect profile, are administered most frequently. In this study, high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) was applied to evaluate penicillin G concentration in serum and bone samples of 19 patients suffering from ARONJ and undergoing surgical treatment under perioperative intravenous (IV) antibiotic therapy. Penicillin G bone concentrations were above the limit of detection (0.1 μg/g bone tissue) in 16 out of 19 samples, with a median concentration of 2.7 μg/g (range 0.1–8.8 μg/g). Penicillin G concentrations in intraoperative serum samples were above the limit of detection in all serum samples, with a median concentration of 116 μg/mL (range 1–232 μg/mL). Thus, considering bacteria frequently found in ARONJ lesions, penicillin G at levels providing adequate antimicrobial activity was detected in the serum and 16 out of 19 osteonecrotic lesions of patients suffering from ARONJ.

Biphasic composite of calcium phosphate-based mesoporous silica as a novel bone drug delivery system

We reported the new biphasic composites of calcium phosphate and mesoporous silica material (CaP@MSi) in the form of powders and pellets as a potential bone drug delivery system for doxycycline hydrochloride (DOX). The CaP@MSi powders were synthesized by cationic surfactant-templating method. The effects of 10, 20, and 30% CaP content in the CaP@MSi powders on the molecular surface structure, the cytotoxicity against osteoblast cells in vitro, and the mineralization potential in simulated body fluid were investigated. The CaP@MSi characterized by the highest mineralization potential (30% CaP content) were used for DOX adsorption and pelletization process. The CaP which precipitated in the CaP@MSi composites was characterized as calcium-deficient with the Ca:P molar ratio between 1.0 and 1.2. The cytotoxicity assays demonstrated that the CaP content in MSi increases osteoblasts viability indicating the CaP@MSi (30% CaP content) as the most biocompatible. The combination of CaP and MSi was an effective strategy to improve the mineralization potential of parent material. Upon immersion in simulated body fluid, the CaP of composite converted into the bone-like apatite. The obtained pellets preserved the mineralization potential of CaP@MSi and provided the prolonged 5-day DOX release. The obtained biphasic CaP@MSi composites seem to have an application potential as bone-specific drug delivery system.

An Antibiotic-Releasing Bone Void Filling (ABVF) Putty for the Treatment of Osteomyelitis

The number of total joint replacements (TJR) is on the rise with a corresponding increase in the number of infected TJR, which necessitates revision surgeries. Current treatments with either non-biodegradable, antibiotic-releasing polymethylmethacrylate (PMMA) based bone cement, or systemic antibiotic after surgical debridement do not provide effective treatment due to fluctuating antibiotic levels at the site of infection. Here, we report a biodegradable, easy-to-use "press-fitting" antibiotic-releasing bone void filling (ABVF) putty that not only provides efficient antibiotic release kinetics at the site of infection but also allows efficient osseointegration. The ABVF formulation was prepared using poly (D,L-lactide-co-glycolide) (PLGA), polyethylene glycol (PEG), and polycaprolactone (PCL) as the polymer matrix, antibiotic vancomycin, and osseointegrating synthetic bone PRO OSTEON for bone-growth support. ABVF was homogenous, had a porous structure, was moldable, and showed putty-like mechanical properties. The ABVF putty released vancomycin for 6 weeks at therapeutic level. Furthermore, the released vancomycin showed in vitro antibacterial activity against Staphylococcus aureus for 6 weeks. Vancomycin was not toxic to osteoblasts. Finally, ABVF was biodegradable in vivo and showed an effective infection control with the treatment group showing significantly higher bone growth (p < 0.001) compared to the control group. The potential of infection treatment and osseointegration makes the ABVF putty a promising treatment option for osteomyelitis after TJR.

Susceptibility of Mature Staphylococcus Biofilms to Chinese Herbal Decoction Sanhuang Jiedu: An In Vitro Study

BACKGROUND

External socking and washing with the Chinese herbal Sanhuang Jiedu decoction (SHJD) can effectively control local limb infections with bone and implant exposure. However, the antibiofilm activities of this decoction in vitro have not yet been investigated. Therefore, the aim of this study was to examine the effects and characteristics of SHJD on the mature biofilms of multidrug-resistant staphylococci on a titanium surface.

METHODS

Biofilm-forming methicillin-resistant Staphylococcus epidermidis ATCC 35984 and S. aureus ATCC 43330, and non-biofilm-forming S. epidermidis ATCC 12228 were selected as the experimental strains. The mature biofilms were prepared on titanium surfaces. The five experimental groups were based on dilution concentrations (DC) of SHJD: the control group (biofilm incubated with 0.85% NaCl solution), the SHJD (DC:1/8) group (initial SHJD solution was diluted 1/8), the SHJD (DC:1/4) group, the SHJD (DC:1/2) group, and the SHJD (DC:1/1) group (initial SHJD solution). The effects of SHJD on the mature biofilms were observed with the bacterial spread plate method, crystal violet (CV) staining, scanning electron microscopy, and confocal laser scanning microscopy.

RESULTS

After culture in tryptic soy broth for 72 h, ATCC 43300 and ATCC 35984 produced mature biofilms and ATCC 12228 did not. The optical density value of ATCC 12228 was 0.11 ± 0.02, significantly lower than that of ATCC 35984 (0.42 ± 0.05) or ATCC 43300 (0.41 ± 0.03) (P < 0.05). The mature biofilms of ATCC 43300 and ATCC 35984 clearly disintegrated when incubated for 12-24 h with SHJD (DC:1/1) or SHJD (DC:1/2), showing only scattered bacterial adhesion. In the SHJD (DC:1/4) group, although many residual bacterial colonies still clustered together, presenting a biofilm structure, it was very looser than that in the SHJD (DC:1/8) group in which the biofilm was similar to that in the control group. For ATCC 12228, only colony adhesion was observed, and the number of colonies decreased as the concentration of SHJD or the culture period increased. The quantitative results for the bacterial spread plate and CV staining showed significant differences between the SHJD groups (P < 0.05).

CONCLUSION

SHJD has antibiofilm activity against multidrug-resistant Staphylococcus strains. It weakens or disrupts already-formed mature biofilms on titanium surfaces in a concentration- and incubation time-dependent manner.

Mesoporous silica pellets as bifunctional bone drug delivery system for cefazolin

For decades, bone drug delivery systems dedicated for osteomyelitis treatment have been investigated as bifunctional materials that exhibit prolonged drug release and mineralization potential. Herein, composite-type pellets based on cefazolin-loaded amino-modified mesoporous silica SBA-15 and microwave-assisted hydroxyapatite were investigated as potential bone drug delivery system in vitro. Pellets were obtained by granulation, extrusion and spheronization methods in laboratory scale and studied in terms of physical properties, drug release, mineralization potential, antimicrobial activity and cytotoxicity towards human osteoblasts. The obtained pellets were characterized for hardness and friability which indicated the pellets durability during further investigations. Prolonged (5-day) release of cefazolin from pellets was observed. The pellets exhibited mineralization potential in simulated body fluid, i.e., a continuous layer of bone-like apatite was formed on the surface of pellets after 28 days of incubation. An antimicrobial assay of pellets revealed an antibacterial effect against Staphylococcus aureus strain during 6 days. No cytotoxic effects of pellets towards human osteoblasts were observed. The obtained results proved that proposed pellets appear to have potential applications as bone drug delivery systems.

Emphysematous osteomyelitis of the clavicle: a pleural process?

Emphysematous osteomyelitis (EO) is a rare infection associated with intraosseous gas. EO is an often fatal disease with an estimated 34% mortality. We present a case of a 63-year-old man with sternoclavicular EO with pleural involvement and significant subcutaneous emphysema diagnosed by CT. Extension of intraosseous gas into the pleural cavity is an extremely interesting presentation that has not been previously reported. The patient underwent a multidisciplinary treatment approach with surgical debridement and an extended antibiotic course. Intraoperative cultures of the pectoralis muscle and bone biopsy grew pan-sensitive Escherichia coli Prompt recognition and treatment are paramount to avoid a potentially fatal outcome. A review of the literature of the previous 46 cases of EO is presented for associated risk factors, the role of surgical management and antibiotic therapy.

Lipid-based nanosystems for targeting bone implant-associated infections: current approaches and future endeavors

Bone infections caused by Staphylococcus aureus are a major concern in medical care, particularly when associated with orthopedic-implant devices. The ability of the bacteria to form biofilms and their capacity to invade and persist within osteoblasts turn the infection eradication into a huge challenge. The reduction of antibiotic penetration through bacterial biofilms associated with the presence of persistent cells, ability to survive in the host, and high tolerance to antibiotics are some of the reasons for the difficult treatment of these infections. Effective therapeutic approaches are urgently needed. In this sense, lipid-based nanosystems, such as liposomes, have been investigated as an innovative and alternative strategy for the treatment of implant-associated S. aureus infections, due to their preferential accumulation at infected sites and interaction with S. aureus. This review highlights the recent advances on antibiotic-loaded liposome formulations both in vitro and in vivo and how the interaction with S. aureus biofilms may be improved by modulating the liposomal external surface. Graphical Abstract.

Extended Release Combination Antibiotic Therapy from a Bone Void Filling Putty for Treatment of Osteomyelitis

In spite of advances in Total Joint Replacements (TJR), infection remains a major concern and a primary causative factor for revision surgery. Current clinical standards treat these osteomyelitis infections with antibiotic-laden poly(methyl methacrylate) (PMMA)-based cement, which has several disadvantages, including inadequate local drug release kinetics, antibiotic leaching for a prolonged period and additional surgical interventions to remove it, etc. Moreover, not all antibiotics (e.g., rifampicin, a potent antibiofilm antibiotic) are compatible with PMMA. For this reason, treatment of TJR-associated infections and related complications remains a significant concern. The objective of this study was to develop a polymer-controlled dual antibiotic-releasing bone void filler (ABVF) with an underlying osseointegrating substrate to treat TJR implant-associated biofilm infections. An ABVF putty was designed to provide sustained vancomycin and rifampicin antibiotic release for 6 weeks while concurrently providing an osseointegrating support for regrowth of lost bone. The reported ABVF showed efficient antibacterial and antibiofilm activity both in vitro and in a rat infection model where the ABVF both showed complete bacterial elimination and supported bone growth. Furthermore, in an in vivo k-wire-based biofilm infection model, the ABVF putty was also able to eliminate the biofilm infection while supporting osseointegration. The retrieved k-wire implants were also free from biofilm and bacterial burden. The ABVF putty delivering combination antibiotics demonstrated that it can be a viable treatment option for implant-related osteomyelitis and may lead to retention of the hardware while enabling single-stage surgery.

What Are the Effects of Irreversible Electroporation on a Staphylococcus aureus Rabbit Model of Osteomyelitis?

BACKGROUND

The treatment of osteomyelitis can be challenging because of poor antibiotic penetration into the infected bone and toxicities associated with prolonged antibiotic regimens to control infection. Irreversible electroporation (IRE), a percutaneous image-guided ablation technology in which the targeted delivery of high-voltage electrical pulses permanently damages the cell membrane, has been shown to effectively control bacterial growth in various settings. However, IRE for the management of bone infections has yet to be evaluated.

QUESTIONS/PURPOSES

We aimed to evaluate IRE for treating osteomyelitis by assessing (1) the efficacy of IRE to suppress the in vitro growth of a clinical isolate of S. aureus, alone or combined with cefazolin; and (2) the effects of IRE on the in vivo treatment of a rabbit model of osteomyelitis.

METHODS

S. aureus strain UAMS-1 expanded in vitro to the log phase was subjected to an electric field of 2700 V/cm, which was delivered in increasing numbers of pulses. Immediately after electroporation, bacteria were plated on agar plates with or without cefazolin. The number of colony-forming units (CFUs) was scored the following day. ANOVA tests were used to analyze in vitro data. In a rabbit osteomyelitis model, we inoculated the same bacterial strain into the radius of adult male New Zealand White rabbits. Three weeks after inoculation, all animals (n = 32) underwent irrigation and débridement, as well as wound culture of the infected forelimb. Then, they were randomly assigned to one of four treatment groups (n = eight per group): untreated control, cefazolin only, IRE only, or combined IRE + cefazolin. Serial radiography was performed to assess disease progression using a semiquantitative grading scale. Bone and soft-tissue specimens from the infected and contralateral forelimbs were collected at 4 weeks after treatment for bacterial isolation and histologic assessment using a semiquantitative scale.

RESULTS

The in vitro growth of S. aureus UAMS-1 was impaired by IRE in a pulse-dependent fashion; the number of CFUs/mL was different among seven pulse levels, namely 0, 10, 30, 60, 90, 120, and 150 pulses. With the number of CFUs/mL observed in untreated controls set as 100%, 10 pulses rendered a median of 50.2% (range 47.1% to 58.2%), 30 pulses rendered a median of 2.7% (range 2.5% to 2.8%), 60 pulses rendered a median of 0.014% (range 0.012% to 0.015%), 90 pulses rendered a median of 0.004% (range 0.002% to 0.004%), 120 pulses rendered a median of 0.001% (range 0.001% to 0.001%), and 150 pulses rendered a median of 0.001% (range 0.000% to 0.001%) (Kruskal-Wallis test: p = 0.003). There was an interaction between the effect of the number of pulses and the concentration of cefazolin (two-way ANOVA: F [8, 30] = 17.24; p < 0.001), indicating that combining IRE with cefazolin is more effective than either treatment alone at suppressing the growth of S. aureus UAMS-1. Likewise, the clinical response in the rabbit model (the percentage of animals without detectable residual bacteria in the bone and surrounding soft tissue after treatment) was better in the combination group than in the other groups: control, 12.5% (one of eight animals); IRE only, 12.5% (one of eight animals); cefazolin only, 25% (two of eight animals); and IRE + cefazolin, 75% (six of eight animals) (two-sided Fisher's exact test: p = 0.030).

CONCLUSIONS

IRE effectively suppressed the growth of S. aureus UAMS-1 and enhanced the antibacterial effect of cefazolin in in vitro studies. When translated to a rabbit osteomyelitis model, the addition of IRE to conventional parenteral antibiotic treatment produced the strongest response, which supports the in vitro findings.

CLINICAL RELEVANCE

Our results show that IRE may improve the results of standard parenteral antibiotic treatment, thus setting the stage for models with larger animals and perhaps trials in humans for validation.

Exebacase in Addition to Daptomycin Is More Active than Daptomycin or Exebacase Alone in Methicillin-Resistant Staphylococcus aureus Osteomyelitis in Rats

Bacteriophage-derived lysins are being developed as anti-infective agents. In an acute osteomyelitis methicillin-resistant Staphylococcus aureus (MRSA) model, rats receiving no treatment or treatment with daptomycin, exebacase (CF-301), or daptomycin plus exebacase had means of 5.13, 4.09, 4.65, and 3.57 log₁₀ CFU/gram of bone, respectively. All treated animals had fewer bacteria than did untreated animals (P ≤ 0.0001), with daptomycin plus exebacase being more active than daptomycin (P = 0.0042) or exebacase (P < 0.001) alone.

Oral versus intravenous antibiotics for bone and joint infections: the OVIVA non-inferiority RCT

BACKGROUND

Management of bone and joint infection commonly includes 4-6 weeks of intravenous (IV) antibiotics, but there is little evidence to suggest that oral (PO) therapy results in worse outcomes.

OBJECTIVE

To determine whether or not PO antibiotics are non-inferior to IV antibiotics in treating bone and joint infection.

DESIGN

Parallel-group, randomised (1 : 1), open-label, non-inferiority trial. The non-inferiority margin was 7.5%.

SETTING

Twenty-six NHS hospitals.

PARTICIPANTS

Adults with a clinical diagnosis of bone, joint or orthopaedic metalware-associated infection who would ordinarily receive at least 6 weeks of antibiotics, and who had received ≤ 7 days of IV therapy from definitive surgery (or start of planned curative treatment in patients managed non-operatively).

INTERVENTIONS

Participants were centrally computer-randomised to PO or IV antibiotics to complete the first 6 weeks of therapy. Follow-on PO therapy was permitted in either arm.

MAIN OUTCOME MEASURE

The primary outcome was the proportion of participants experiencing treatment failure within 1 year. An associated cost-effectiveness evaluation assessed health resource use and quality-of-life data.

RESULTS

Out of 1054 participants (527 in each arm), end-point data were available for 1015 (96.30%) participants. Treatment failure was identified in 141 out of 1015 (13.89%) participants: 74 out of 506 (14.62%) and 67 out of 509 (13.16%) of those participants randomised to IV and PO therapy, respectively. In the intention-to-treat analysis, using multiple imputation to include all participants, the imputed risk difference between PO and IV therapy for definitive treatment failure was -1.38% (90% confidence interval -4.94% to 2.19%), thus meeting the non-inferiority criterion. A complete-case analysis, a per-protocol analysis and sensitivity analyses for missing data each confirmed this result. With the exception of IV catheter complications [49/523 (9.37%) in the IV arm vs. 5/523 (0.96%) in the PO arm)], there was no significant difference between the two arms in the incidence of serious adverse events. PO therapy was highly cost-effective, yielding a saving of £2740 per patient without any significant difference in quality-adjusted life-years between the two arms of the trial.

LIMITATIONS

The OVIVA (Oral Versus IntraVenous Antibiotics) trial was an open-label trial, but bias was limited by assessing all potential end points by a blinded adjudication committee. The population was heterogenous, which facilitated generalisability but limited the statistical power of subgroup analyses. Participants were only followed up for 1 year so differences in late recurrence cannot be excluded.

CONCLUSIONS

PO antibiotic therapy is non-inferior to IV therapy when used during the first 6 weeks in the treatment for bone and joint infection, as assessed by definitive treatment failure within 1 year of randomisation. These findings challenge the current standard of care and provide an opportunity to realise significant benefits for patients, antimicrobial stewardship and the health economy.

FUTURE WORK

Further work is required to define the optimal total duration of therapy for bone and joint infection in the context of specific surgical interventions. Currently, wide variation in clinical practice suggests significant redundancy that likely contributes to the excess and unnecessary use of antibiotics.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN91566927.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 38. See the NIHR Journals Library website for further project information.

Antibiotic penetration into bone and joints: An updated review

Treatment of bone and joint infections can be challenging as antibiotics should penetrate through the rigid bone structure and into the synovial space. Several pharmacokinetic studies measured the extent of penetration of different antibiotics into bone and joint tissues. This review discusses the results of these studies and compares them with minimum inhibitory concentrations (MIC) of common pathogens implicated in bone and joint infections in order to determine which antibiotics may have a greater potential in the treatment of such infections. Clinical outcomes were also evaluated as data were available. More than 30 antibiotics were evaluated. Overall, most antibiotics, including amoxicillin, piperacillin/tazobactam, cloxacillin, cephalosporins, carbapenems, aztreonam, aminoglycosides, fluoroquinolones, doxycycline, vancomycin, linezolid, daptomycin, clindamycin, trimethoprim/sulfamethoxazole, fosfomycin, rifampin, dalbavancin, and oritavancin, showed good penetration into bone and joint tissues reaching concentrations exceeding the MIC₉₀ and/or MIC breakpoints of common bone and joint infections pathogens. Few exceptions include penicillin and metronidazole which showed a lower than optimum penetration into bones, and the latter as well as flucloxacillin had poor profiles in terms of joint space penetration. Of note, studies on joint space penetration were fewer than studies on bone tissue penetration. Although clinical studies in osteomyelitis and septic arthritis are not available for all of the evaluated antibiotics, these pharmacokinetic results indicate that agents with good penetration profiles would have a potential utilization in such infections.

Selection of an appropriate empiric antibiotic regimen in hematogenous vertebral osteomyelitis

Background

Empiric antibiotic therapy for suspected hematogenous vertebral osteomyelitis (HVO) should be initiated immediately in seriously ill patients and may be required in those with negative microbiological results. The aim of this study was to inform the appropriate selection of empiric antibiotic regimens for the treatment of suspected HVO by analyzing antimicrobial susceptibility of isolated bacteria from microbiologically proven HVO.

Method

We conducted a retrospective chart review of adult patients with microbiologically proven HVO in five tertiary-care hospitals over a 7-year period. The appropriateness of empiric antibiotic regimens was assessed based on the antibiotic susceptibility profiles of isolated bacteria.

Results

In total, 358 cases of microbiologically proven HVO were identified. The main causative pathogens identified were methicillin-susceptible Staphylococcus aureus (33.5%), followed by methicillin-resistant S. aureus (MRSA) (24.9%), Enterobacteriaceae (19.3%), and Streptococcus species (11.7%). Extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and anaerobes accounted for only 1.7% and 1.4%, respectively, of the causative pathogens. Overall, 73.5% of isolated pathogens were susceptible to levofloxacin plus rifampicin, 71.2% to levofloxacin plus clindamycin, and 64.5% to amoxicillin-clavulanate plus ciprofloxacin. The susceptibility to these oral combinations was lower in cases of healthcare-associated HVO (52.6%, 49.6%, and 37.6%, respectively) than in cases of community-acquired HVO (85.8%, 84.0%, and 80.4%, respectively). Vancomycin combined with ciprofloxacin, ceftriaxone, ceftazidime, or cefepime was similarly appropriate (susceptibility rates of 93.0%, 94.1%, 95.8%, and 95.8%, respectively).

Conclusions

Based on our susceptibility data, vancomycin combined with a broad-spectrum cephalosporin or fluoroquinolone may be appropriate for empiric treatment of HVO. Fluoroquinolone-based oral combinations may be not appropriate due to frequent resistance to these agents, especially in cases of healthcare-associated HVO.

The synergistic therapeutic efficacy of vancomycin and omega-3 fatty acids alleviates Staphylococcus aureus-induced osteomyelitis in rats

Our study evaluated the synergistic impact of vancomycin and omega-3 fatty acids against osteomyelitis in a Staphylococcus aureus-induced rat model of osteomyelitis. The animals were grouped as follows: sham (group I), osteomyelitis (group II, control), vancomycin (20 mg/kg body weight, group III), omega-3 fatty acids (20 mg/kg body weight, group IV) and vancomycin (20 mg/kg body weight) + omega-3 fatty acids (20 mg/kg body weight) (group V). Lipid peroxidation, superoxide dismutase (SOD), glutathione peroxidase (Gpx), catalase, reduced glutathione (GSH), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were measured. The determination of bacterial growth and histopathological analyses were carried out. The lipid peroxidation, GSH, SOD, catalase and Gpx levels recovered to near-normal levels following combined treatment with vancomycin and omega-3 fatty acids. The TNF-α and IL-6 levels were reduced to near-normal levels. Combined supplementation with vancomycin and omega-3 fatty acids significantly reduced bacterial growth in bone and the implanted wire. Furthermore, the bone infection levels and histopathological score were reduced. In summary, combined treatment with vancomycin and omega-3 fatty acids was effective against bacterial growth and bone infection compared to monotherapy with vancomycin or omega-3 fatty acids.

Antibacterial surface modification of titanium implants in orthopaedics

The use of biomaterials in orthopaedics for joint replacement, fracture healing and bone regeneration is a rapidly expanding field. Infection of these biomaterials is a major healthcare burden, leading to significant morbidity and mortality. Furthermore, the cost to healthcare systems is increasing dramatically. With advances in implant design and production, research has predominately focussed on osseointegration; however, modification of implant material, surface topography and chemistry can also provide antibacterial activity. With the increasing burden of infection, it is vitally important that we consider the bacterial interaction with the biomaterial and the host when designing and manufacturing future implants. During this review, we will elucidate the interaction between patient, biomaterial surface and bacteria. We aim to review current and developing surface modifications with a view towards antibacterial orthopaedic implants for clinical applications.