Adherent bacterial colonization in the pathogenesis of osteomyelitis

Beyond antibiotics: CRISPR/Cas9 triumph over biofilm-associated antibiotic resistance infections

A complex structure known as a biofilm is formed when a variety of bacterial colonies or a single type of cell in a group sticks to a surface. The extracellular polymeric compounds that encase these cells, often consisting of proteins, eDNA, and polysaccharides, exhibit strong antibiotic resistance. Concerns about biofilm in the pharmaceutical industry, public health, and medical fields have sparked a lot of interest, as antibiotic resistance is a unique capacity exhibited by these biofilm-producing bacteria, which increases morbidity and death. Biofilm formation is a complicated process that is controlled by several variables. Insights into the processes to target for the therapy have been gained from multiple attempts to dissect the biofilm formation process. Targeting pathogens within a biofilm is profitable because the bacterial pathogens become considerably more resistant to drugs in the biofilm state. Although biofilm-mediated infections can be lessened using the currently available medications, there has been a lot of focus on the development of new approaches, such as bioinformatics tools, for both treating and preventing the production of biofilms. Technologies such as transcriptomics, metabolomics, nanotherapeutics and proteomics are also used to develop novel anti-biofilm agents. These techniques help to identify small compounds that can be used to inhibit important biofilm regulators. The field of appropriate control strategies to avoid biofilm formation is expanding quickly because of this spurred study. As a result, the current article addresses our current knowledge of how biofilms form, the mechanisms by which bacteria in biofilms resist antibiotics, and cutting-edge treatment approaches for infections caused by biofilms. Furthermore, we have showcased current ongoing research utilizing the CRISPR/Cas9 gene editing system to combat bacterial biofilm infections, particularly those brought on by lethal drug-resistant pathogens, concluded the article with a novel hypothesis and aspirations, and acknowledged certain limitations.

Bacterial biofilms in the human body: prevalence and impacts on health and disease

Bacterial biofilms can be found in most environments on our planet, and the human body is no exception. Consisting of microbial cells encased in a matrix of extracellular polymers, biofilms enable bacteria to sequester themselves in favorable niches, while also increasing their ability to resist numerous stresses and survive under hostile circumstances. In recent decades, biofilms have increasingly been recognized as a major contributor to the pathogenesis of chronic infections. However, biofilms also occur in or on certain tissues in healthy individuals, and their constituent species are not restricted to canonical pathogens. In this review, we discuss the evidence for where, when, and what types of biofilms occur in the human body, as well as the diverse ways in which they can impact host health under homeostatic and dysbiotic states.

Quantifiable Relationship Between Antibacterial Efficacy and Electro-Mechanical Intervention on Nanowire Arrays

Physical disruption is an important antibacterial means as it is lethal to bacteria without spurring antimicrobial resistance. However, it is very challenging to establish a quantifiable relationship between antibacterial efficacy and physical interactions such as mechanical and electrical forces. Herein, titanium nitride (TN) nanowires with adjustable orientations and capacitances are prepared to exert gradient electro-mechanical forces on bacteria. While vertical nanowires show the strongest mechanical force resulting in an antibacterial efficiency of 0.62 log reduction (vs 0.22 for tiled and 0.36 for inclined nanowires, respectively), the addition of electrical charges maximizes the electro-mechanical interactions and elevates the antibacterial efficacy to more than 3 log reduction. Biophysical and biochemical analyses indicate that electrostatic attraction by electrical charge narrows the interface. The electro-mechanical intervention more easily stiffens and rips the bacteria membrane, disturbing the electron balance and generating intracellular oxidative stress. The antibacterial ability is maintained in vivo and bacteria-challenged rats are protected from serious infection. The physical bacteria-killing process demonstrated here can be controlled by adjusting the electro-mechanical interactions. Overall, these results revealed important principles for rationally designing high-performance antibacterial interfaces for clinical applications.

In Situ Coatings of Silver Nanoparticles for Biofilm Treatment in Implant-Retention Surgeries: Antimicrobial Activities in Monoculture and Coculture

Bacterial biofilms are indicated in most medical device-associated infections. Treating these biofilms is challenging yet critically important for applications such as in device-retention surgeries, which can have reinfection rates of up to 80%. This in vitro study centered around our new method of treating biofilm and preventing reinfection. Ionic silver (Ag, in the form of silver nitrate) combined with dopamine and a biofilm-lysing enzyme (α-amylase) were applied to model 4-day-old Staphylococcus aureus biofilms on titanium substrates to degrade the extracellular matrix of the biofilm and kill the biofilm bacteria. In this process, the oxidative self-polymerization of dopamine converted Ag ions into Ag nanoparticles that, together with the resultant self-adhering polydopamine (PDA), formed coatings that strongly bound to the treated substrates. Surprisingly, although these Ag/PDA coatings significantly reduced S. aureus growth in standard bacterial monoculture, they showed much lower antimicrobial activity in coculture of the bacteria and osteoblastic MC3T3-E1 cells in which the bacteria were also found attached to the osteoblasts. This S. aureus- osteoblast interaction was also linked to bacterial survival against gentamicin treatment observed in coculture. Our study thus provided clear evidence suggesting that bacteria's interactions with tissue cells surrounding implants may significantly contribute to their resistance to antimicrobial treatment.

Impact of the Host-Microbiome on Osteomyelitis Pathogenesis

The microbiome is a collection of genomes from microbiota, including all microorganisms in a niche, through direct and indirect interactions with the host. Certain microorganisms can exist in areas conventionally considered to be sterile, such as the bone matrix. Osseous microbiota dysbiosis caused by host-microbiome perturbation or external infections may ultimately lead to osteomyelitis, a bone inflammatory disorder. Our review covers the current discoveries on the impact of host-microbiome on osteomyelitis and some common osseous diseases. Some studies suggest that the microbiotas from both osseous and non-osseous tissues (e.g., blood or gut) impact the pathogenicity of osteomyelitis and other osseous diseases (e.g., rheumatoid arthritis). We believe that this review will provide readers with a better understanding on the role of the microbiome to the host’s bone health.

Gallium Porphyrin and Gallium Nitrate Reduce the High Vancomycin Tolerance of MRSA Biofilms by Promoting Extracellular DNA-Dependent Biofilm Dispersion

Biofilms, structured communities of bacterial cells embedded in a self-produced extracellular matrix (ECM) which consists of proteins, polysaccharide intercellular adhesins (PIAs), and extracellular DNA (eDNA), play a key role in clinical infections and are associated with an increased morbidity and mortality by protecting the embedded bacteria against drug and immune response. The high levels of antibiotic tolerance render classical antibiotic therapies impractical for biofilm-related infections. Thus, novel drugs and strategies are required to reduce biofilm tolerance and eliminate biofilm-protected bacteria. Here, we showed that gallium, an iron mimetic metal, can lead to nutritional iron starvation and act as dispersal agent triggering the reconstruction and dispersion of mature methicillin-resistant Staphylococcus aureus (MRSA) biofilms in an eDNA-dependent manner. The extracellular matrix, along with the integral bacteria themselves, establishes the integrated three-dimensional structure of the mature biofilm. The structures and compositions of gallium-treated mature biofilms differed from those of natural or antibiotic-survived mature biofilms but were similar to those of immature biofilms. Similar to immature biofilms, gallium-treated biofilms had lower levels of antibiotic tolerance, and our in vitro tests showed that treatment with gallium agents reduced the antibiotic tolerance of mature MRSA biofilms. Thus, the sequential administration of gallium agents (gallium porphyrin and gallium nitrate) and relatively low concentrations of vancomycin (16 mg/L) effectively eliminated mature MRSA biofilms and eradicated biofilm-enclosed bacteria within 1 week. Our results suggested that gallium agents may represent a potential treatment for refractory biofilm-related infections, such as prosthetic joint infections (PJI) and osteomyelitis, and provide a novel basis for future biofilm treatments based on the disruption of normal biofilm-development processes.

Merlin functions as a critical regulator in Staphylococcus aureus-induced osteomyelitis

Merlin is known as a tumor suppressor, while its role in osteomyelitis remains unclear. This study aimed to investigate the role of Merlin in Staphylococcus aureus-induced osteomyelitis and its underlying mechanisms. S. aureus-induced osteomyelitis mouse model was established in Merlin^fl/fl Lyz2^cre/+ and Merlin^fl/fl Lyz2^+/+ mice. Bone marrow-derived macrophages (BMDMs) were isolated and stimulated by lipopolysaccharide (LPS). Bioassays, including quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blot analysis, and enzyme-linked immunosorbent assays, were conducted to determine the levels of target genes or proteins. Immunoprecipitation was applied to determine the interactions between proteins. DCAF1^fl/fl mice were further crossed with Lyz2-Cre mice to establish myeloid cell conditional knockout mice (DCAF1^fl/fl Lyz2^cre/+ ). It was found that the level of Merlin was elevated in patients with osteomyelitis and S. aureus-infected BMDMs. Merlin deficiency in macrophages suppressed the production of inflammatory cytokines and ameliorated the symptoms of osteomyelitis induced by S. aureus. Merlin deficiency in macrophages also suppressed the production of proinflammatory cytokines in BMDMs induced by LPS. The inhibitory effects of Merlin deficiency on the inflammatory response were associated with DDB1-Cul4-associated factor 1 (DCAF1). In summary, Merlin deficiency ameliorates S. aureus-induced osteomyelitis through the regulation of DCAF1.

Histopathologic findings in culture-positive secondary osteomyelitis

As peripheral vascular disease and diabetes mellitus are increasingly common, chronic wounds are often seen. Bone biopsies, with imaging and microbial cultures, are often obtained to evaluate for osteomyelitis. Because much of the historical literature describing the histology of osteomyelitis pertains to primary osteomyelitis, this study characterizes the histologic findings and provides correlation with culture results in secondary osteomyelitis. The histologic features of bone biopsies were assessed over a 5 year period. Concurrent laboratory and radiographic data were obtained and these data were compared with culture results. This study included 163 cases, of which 104 were culture-positive osteomyelitis. All culture-positive cases had been present longer than 28 days and had at least one of the following histologic features: neutrophilic inflammation, plasmacytic inflammation, or eosinophilic fibrosis. However, none of these findings were restricted to culture-positive cases. Overall, plasmacytic and neutrophilic inflammation provided similar specificity, and positive predictive values for osteomyelitis. Medullary fibrosis gave a sensitivity of 95%, the highest for any single feature, and the combination of fibrosis and neutrophilic inflammation had the greatest specificity of 96%. Additionally, neutrophilic inflammation correlated often with isolation of Staphylococcus aureus, while plasma cell predominance was found more frequently with other infectious agents. This study describes histologic features in secondary osteomyelitis, which may challenge the widespread inclination to equate a neutrophilic inflammation with 'acute osteomyelitis' and 'chronic osteomyelitis' with one rich in plasma cells. We report an early correlation between common histopathologic findings and specific culture isolates, which can be further refined with additional research.

Surgical Site Infections after glioblastoma surgery: results of a multicentric retrospective study

BACKGROUND

The effects of surgical site infections (SSI) after glioblastoma surgery on patient outcomes are understudied. The aim of this retrospective multicenter study was to evaluate the impact of SSI on the survival of glioblastoma patients.

METHODS

Data from SSI cases after glioblastoma surgeries between 2009 and 2016 were collected from 14 French neurosurgical centers. Collected data included patient demographics, previous medical history, risk factors, details of the surgical procedure, radiotherapy/chemotherapy, infection characteristics, and infection management. Similar data were collected from gender- and age-paired control individuals.

RESULTS

We used the medical records of 77 SSI patients and 58 control individuals. 13 were excluded. Our analyses included data from 64 SSI cases and 58 non-infected glioblastoma patients. Infections occurred after surgery for primary tumors in 38 cases (group I) and after surgery for a recurrent tumor in 26 cases (group II). Median survival was 381, 633, and 547 days in patients of group I, group II, and the control group, respectively. Patients in group I had significantly shorter survival compared to the other two groups (p < 0.05). The one-year survival rate of patients who developed infections after surgery for primary tumors was 50%. Additionally, we found that SSIs led to postoperative treatment discontinuation in 30% of the patients.

DISCUSSION

Our findings highlighted the severity of SSIs after glioblastoma surgery, as they significantly affect patient survival. The establishment of preventive measures, as well as guidelines for the management of SSIs, is of high clinical importance.

Biofilm and Foreign Body Infection the Significance to Capd-Associated Peritonitis

Microbial colonization of indwelling and implantable medical devices and prostheses is known to precede the formation of an adherent biofilm, such as is found on peritoneal catheters during CAPD. Micro-organismderived exopolysaccharides within the biofilm matrix seem to confer unique biological properties on this material, such as enhanced resistance to host defenses and antimicrobial agents. It has been proposed that an adherent biofilm is a major contributing factor in the development of foreign-body infections, including CAPD peritonitis. The source of organisms which lead to biofilm formation on peritoneal catheters is unknown but may include “seeding” at the time of surgical placement and migration from the subcutaneous tunnel via the inner cuff.

Strategies to inhibit biofilm development in industrial systems usually involve physical destruction of the biofilm and the use of biocides. Clinical success has been achieved by antimicrobial agents impregnated into or coated onto susceptible devices. Microbial adhesion to inanimate surfaces is a complex and multifaceted event. Continued research in this area, however, should increase our understanding of the factors involved underlying foreignbody infection.

Understanding dental plaque; biofilm dynamics

A biofilm is a well organized community of cooperating microorganisms. Biofilms predictably form in nature, in artificial environments, and on medically implanted prostheses and indwelling venous catheters. They also form on tooth surfaces in the form of dental plaque. The intent of this article is to aid in the understanding of dental plaque by exploring biofilm structure, nature and dynamics. Understanding plaque facilitates its treatment and control.

Design, synthesis and valued properties of surfactin oversimplified analogues

Surfactins are important lipopeptides produced by Bacillus subtilis that present strong surface activity. These biosurfactants find applications in various fields, from environmental remediation to medicine. The use of surfactins in remediation is hampered by production costs; the medical applications are also reframed because of the hemolytic activity of the cyclic peptide. To reduce costs and working time, the present work focused on the design, chemical synthesis and characterization of simple linear variants of surfactins having only L-amino acids and lauric acid at the N-terminal. Carboxyl-free and amidated analogues with negative, null and positive net charges at physiological pH were successfully obtained. The synthetic isoforms of surfactins showed high surface activity and ability to inhibit both growth and adhesion of Streptococcus mutans cells. Therefore, these properties make these low-cost synthetic peptides relevant and promising new compounds for science, industry and, mainly, dental care.

High-resolution bimodal imaging and potent antibiotic/photodynamic synergistic therapy for osteomyelitis with a bacterial inflammation-specific versatile agent

Unsatisfactory diagnosis and therapy of osteomyelitis are still common but challenging issues for clinicians. To overcome these problems, a bacterial inflammation-specific multifunctional agent, denoted bovine serum albumin-manganese dioxide-ubiquicidin_29-41-indocyanine green (ICG) -gentamicin (BMUIG), was synthesized for combined high-resolution bimodal imaging and antibiotic/photodynamic therapy for osteomyelitis. BMUIG binding affinity and antibacterial ability were assessed by using Staphylococcus aureus (S. aureus). Photoacoustic/magnetic resonance imaging was performed on a mouse model of acute osteomyelitis after intravenous injection of BMUIG. Then, myelitis-bearing mice were treated with antibiotic/photodynamic combination therapy. BMUIG specifically targeted S. aureus in comparison with non-targeted agents. In the osteomyelitis model, the infection area was identified accurately and quickly through ICG-based photoacoustic imaging and Mn²⁺-based T₁ magnetic resonance imaging after injection of BMUIG. Furthermore, the manganese dioxide in BMUIG reacted with the locally produced hydrogen peroxide under acidic inflammatory conditions, continuously generating oxygen for enhanced photodynamic therapy. In combination with low-dose gentamicin, a synergistic antibacterial effect was observed and bone infection was resolved. In summary, a non-invasive accurate diagnosis and effective synergistic therapy for osteomyelitis was successfully developed using a bacterial inflammation-specific versatile agent, which would provide a sound theranostic strategy for common infectious diseases. STATEMENT OF SIGNIFICANCE: Osteomyelitis is one of the most serious consequences in orthopedics. However, its inaccurate diagnosis and low-effective antibiotic treatment are still common but challenging issues for clinicians. To overcome these problems, we uniquely designed a bacterial inflammation-specific multifunctional nanoagent, bovine serum albumin-manganese dioxide-ubiquicidin_29-41-indocyanine green-gentamicin (BMUIG), for high-resolution bimodal imaging and antibiotic/photodynamic combined therapy of osteomyelitis. Herein, high-resolution imaging technologies refer to classic magnetic resonance imaging and emerging photoacoustic imaging. Photodynamic therapy is subtly introduced because of its safe and effective killing mechanism, which can synergize the bactericidal effect of antibiotics. As a result, we successfully realize non-invasive accurate diagnosis and effective synergistic therapy for osteomyelitis by virtue of the bacterial inflammation-specific versatile agent, which will serve as a promising candidate for sound theranostics in common infectious diseases.

Bifocal Bone Transport over a Preexisting Nail to Treat a Septic Femoral Shaft Nonunion

Intramedullary nailing is the method of choice for the treatment of most femoral shaft fractures. However, it is not always an easy procedure with predictable results as leg length discrepancy as well as rotational and angular malunion may occur. Lengthening over an intramedullary nail (IMN) has become very common as it allows early removal of the external fixator. This report presents a case of an open femoral shaft fracture initially treated with an IMN and subsequently complicated by a septic nonunion. Union was obtained by bifocal bone transport with a circular external fixator over the preexisting nail without exchange or removal of the previously inserted IMN. In conclusion, the presence of an IMN supports osteotomy and regenerates bone during bone healing, prevents fracture and/or deformation of the regenerated bone, and reduces the time needed for the external fixator.

Bone transport with a unilateral external fixator for femoral infected nonunion after intramedullary nailing fixation: A case control study

This is a therapeutic study to evaluate the results of femoral infected nonunion using bone transport with an external fixator after debridement and irrigation. We retrospectively reviewed 15 patients with femoral infected nonunion after intramedullary nailing fixation of fractures from October 1999 to January 2010 in our institute. There were 7 males and 8 females with an average age of 32.5 years. First, the infection was eradicated completely, and the medullary canals were continuous irrigated for 2-3 weeks. After eradicating the infection tissues, the mean amount of bone defect was 8.7 cm (range, 4.0-16.0 cm). The unilateral consecutive distraction-compression osteosynthesis technique was applied after long-time medullary cavity-wound exclusion surgery. Enumeration data was described by frequency and measurement data by mean. Bone infections were controlled in all patients except 1 patient after the first debridement and irrigation. All patients have achieved bony union without recurrence of infection during the follow-up period, the mean external fixation index was 43.4 day/cm. According to the criteria recommended by Paley, the bone results were graded as excellent in 13 (86.7%) cases and good in 2 (13.3%) cases; the functional results were graded as excellent in 6 (40.0%) cases, good in 6 (40.0%) cases and fair in 3 (20.0%) cases. In management of femoral infectious nonunion which caused by intramedullary nailing fixation, the surgery of consecutive compression-distraction osteogenesis with unilateral external fixator achieves a highly effective treatment, and the method of debridement and irrigation is a compatible choice on the phase of infection-elimination.

Current Status of In Vitro Models and Assays for Susceptibility Testing for Wound Biofilm Infections

Biofilm infections have gained recognition as an important therapeutic challenge in the last several decades due to their relationship with the chronicity of infectious diseases. Studies of novel therapeutic treatments targeting infections require the development and use of models to mimic the formation and characteristics of biofilms within host tissues. Due to the diversity of reported in vitro models and lack of consensus, this review aims to provide a summary of in vitro models currently used in research. In particular, we review the various reported in vitro models of Pseudomonas aeruginosa biofilms due to its high clinical impact in chronic wounds and in other chronic infections. We assess advances in in vitro models that incorporate relevant multispecies biofilms found in infected wounds, such as P. aeruginosa with Staphylococcus aureus, and additional elements such as mammalian cells, simulating fluids, and tissue explants in an attempt to better represent the physiological conditions found at an infection site. It is hoped this review will aid researchers in the field to make appropriate choices in their proposed studies with regards to in vitro models and methods.

Sonication versus Tissue Sampling for Diagnosis of Prosthetic Joint and Other Orthopedic Device-Related Infections

Current guidelines recommend collection of multiple tissue samples for diagnosis of prosthetic joint infections (PJI). Sonication of explanted devices has been proposed as a potentially simpler alternative; however, reported microbiological yield varies. We evaluated sonication for diagnosis of PJI and other orthopedic device-related infections (DRI) at the Oxford Bone Infection Unit between October 2012 and August 2016. We compared the performance of paired tissue and sonication cultures against a "gold standard" of published clinical and composite clinical and microbiological definitions of infection. We analyzed explanted devices and a median of five tissue specimens from 505 procedures. Among clinically infected cases the sensitivity of tissue and sonication culture was 69% (95% confidence interval, 63 to 75) and 57% (50 to 63), respectively (P < 0.0001). Tissue culture was more sensitive than sonication for both PJI and other DRI, irrespective of the infection definition used. Tissue culture yield was higher for all subgroups except less virulent infections, among which tissue and sonication culture yield were similar. The combined sensitivity of tissue and sonication culture was 76% (70 to 81) and increased with the number of tissue specimens obtained. Tissue culture specificity was 97% (94 to 99), compared with 94% (90 to 97) for sonication (P = 0.052) and 93% (89 to 96) for the two methods combined. Tissue culture is more sensitive and may be more specific than sonication for diagnosis of orthopedic DRI in our setting. Variable methodology and case mix may explain reported differences between centers in the relative yield of tissue and sonication culture. Culture yield was highest for both methods combined.

pH-responsive and porous vancomycin-loaded PLGA microspheres: evidence of controlled and sustained release for localized inflammation inhibition in vitro

Adequate delivery of antibiotics to infected sites is crucial for the effective treatment of bacterial infections. A controlled and sustained release system based on porous and pH-responsive poly(lactic-co-glycolic acid) (PLGA)-vancomycin (Van) microspheres was developed. In this system, drug release is triggered by the weakly acidic environment, like local inflamed tissues. The microspheres, developed through the W1/O/W2 double-emulsion evaporation method, comprised a PLGA-based shell and a core containing Van and the bubble-generating agent of NaHCO3. The optimized preparation conditions for PLGA-NaHCO3-Van microspheres were investigated and characterized. The PLGA-NaHCO3-Van microspheres exhibited porous microstructures with regular shape and uniform size and the characteristic of controlled drug release, which could be attributed to the incorporation of NaHCO3. The results of the Kirby-Bauer assay confirmed that released Van retained effective antibacterial activity towards standard Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) infected clinical samples, suggesting their further promising application in local anti-infection.

Presurgical localization of infected avascular bone segments in chronic complicated posttraumatic osteomyelitis in the lower extremity using dual-tracer PET/CT

Background

Localizing and removing the infected sequestrum in long-standing trauma-related chronic osteomyelitis remains a clinical challenge. PET/CT with 18F-fluorodeoxyglucose (FDG-PET) has a high sensitivity for chronic osteomyelitis and 18F-sodium-fluoride PET/CT (NaF-PET) has a high specificity for identifying non-viable bone. Combining both, high signal on FDG-PET in the bone without signal on NaF-PET could potentially guide surgery to become more precise with curative intent.

Eight patients with long-standing (average 22 years) posttraumatic (n = 7) or postoperative (n = 1) chronic osteomyelitis in the lower extremity and with multiple futile attempts for curative surgery were recruited in this prospective pilot study. FDG-PET and NaF-PET were performed within a week in between using standard scanning protocols. The most likely location of the culprit sequestrum was identified and was surgically removed. Based on perioperative tissue cultures, antibiotics were given for 6–8 months. Dual-tracer (FDG- and NaF-PET/CT) was performed again after 12 months to rule out persisting signs of infection.

Results

A likely culprit sequestrum could preoperatively be identified by dual-tracer PET in all eight cases and in four cases an additional sequestrum was identified at a location with no clinical sign of infection. The infected necrotic tissue was removed during surgery. Follow-up dual-tracer PET revealed no signs of persistent infection. All patients recovered with no clinical signs of recurrence for a follow-up of mean 4.5 (SD 1.3) years.

Conclusions

Dual-tracer PET/CT with FDG and NaF allows successful precise surgery with curative intent in patients with long-standing complicated posttraumatic chronic osteomyelitis with severely deranged anatomy.

Practical Measures to Control Device-Related Bacterial Infections

Direct examination of medical devices that have been foci of chronic device-related bacterial infections has shown that the causative organisms grow predominantly in slime-enclosed biofilms. These adherent biofilms are inherently resistant to host defences (antibodies, phagocytes) and to conventional antibiotic therapy. Device-related infections can be prevented by careful cleaning and sterilization of the device, and by the avoidance of any manipulations that would allow the formation of even the most rudimentary biofilm prior to implantation. Once a device-related infection has become established, both the Minimum Inhibitory Concentration (MIC) and the Biofilm Eliminating Concentration (BEC) of the causative organism must be determined and therapeutic strategy must aim at the use of the MIC to control the acute phase caused by planktonic bacteria and of the BEC to eliminate the biofilm nidus of infection. The removal of the colonized device should be considered early in the course of treatment if the BEC cannot be delivered to the colonized device. We describe a new bioelectric technology presently in the in vitro stage of development which, if it can be reproduced in vivo, will be very effective in the prevention and control of device-related bacterial infections.

Cell Biology and Molecular Mechanisms in Artificial Device Infections

Biomaterials are being used with increasing frequency for tissue substitution. Complex devices such as total joint replacement and the total artificial heart represent combinations of polymers and metal alloys for system and organ replacement. The major barrier to the extended use of these devices is bacterial adhesion to biomaterials, which causes biomaterial-centered infection, and the lack of successful tissue integration or compatibility with biomaterial surfaces. Adhesion-mediated infections are extremely resistant to antibiotics and host defenses and frequently persist until the biomaterial or foreign body is removed. The pathogenesis of adhesive infections is related, in part, to preferential colonization of “inert” substrata whose surfaces are not integrated with healthy tissues composed of living cells and intact extracellular polymers. Tissue integration is an interesting parallel to microbial adhesion and is a desired phenomenon for the biocompatibility of certain implants and biomaterials. Tissue integration requires a form of eukaryocytic adhesion or compatibility with possible chemical integration to an implant surface. Many of the fundamental principles of interfacial science apply to both microbial adhesion and to tissue integration and are general to and independent of the substratum materials involved. Interactions of biomaterials with bacteria and tissue cells are directed not only by specific receptors and outer membrane molecules on the cell surface, but also by the atomic geometry and electronic state of the biomaterial surface. An understanding of these mechanisms is important to all fields of medicine and is derived from and relevant to studies in microbiology, biochemistry, and physics. Modifications of biomaterial surfaces at an atomic level will allow the programming of cell-to-substratum events, thereby diminishing infection by enhancing tissue compatibility or integration, or by directly inhibiting bacterial adhesion.

Multifunctional pH sensitive 3D scaffolds for treatment and prevention of bone infection

Multifunctional-therapeutic three-dimensional (3D) scaffolds have been prepared. These biomaterials are able to destroy the S. aureus bacterial biofilm and to allow bone regeneration at the same time. The present study is focused on the design of pH sensitive 3D hierarchical meso-macroporous 3D scaffolds based on MGHA nanocomposite formed by a mesostructured glassy network with embedded hydroxyapatite nanoparticles, whose mesopores have been loaded with levofloxacin (Levo) as antibacterial agent. These 3D platforms exhibit controlled and pH-dependent Levo release, sustained over time at physiological pH (7.4) and notably increased at infection pH (6.7 and 5.5), which is due to the different interaction rate between diverse Levo species and the silica matrix. These 3D systems are able to inhibit the S. aureus growth and to destroy the bacterial biofilm without cytotoxic effects on human osteoblasts and allowing an adequate colonization and differentiation of preosteoblastic cells on their surface. These findings suggest promising applications of these hierarchical MGHA nanocomposite 3D scaffolds for the treatment and prevention of bone infection.

STATEMENT OF SIGNIFICANCE

Multifunctional 3D nanocomposite scaffolds with the ability for loading and sustained delivery of an antimicrobial agent, to eliminate and prevent bone infection and at the same time to contribute to bone regeneration process without cytotoxic effects on the surrounding tissue has been proposed. These 3D scaffolds exhibit a sustained levofloxacin delivery at physiological pH (pH 7.4), which increasing notably when pH decreases to characteristic values of bone infection process (pH 6.7 and pH 5.5). In vitro competitive assays between preosteoblastic and bacteria onto the 3D scaffold surface demonstrated an adequate osteoblast colonization in entire scaffold surface together with the ability to eliminate bacteria contamination.

Intensity of 18F-FDG PET Uptake in Culture-Negative and Culture-Positive Cases of Chronic Osteomyelitis

Microbiologic cultures are not infrequently negative in patients with a histopathologic diagnosis of chronic osteomyelitis. Culture-negative cases may represent low-grade infections with a lower metabolic activity than culture-positive cases. ¹⁸F-FDG PET could potentially detect such a difference. We determined whether the level of ¹⁸F-FDG PET uptake differs in patients with culture-negative and culture-positive osteomyelitis. We reviewed the clinical charts of 40 consecutive patients, who had diagnostic ¹⁸F-FDG PET for a suspected bone infection. Twenty-six patients were eligible with a confirmed diagnosis based on microbiologic cultures and/or histopathologic examination. Sixteen of 26 patients had chronic osteomyelitis. Eight of them had positive cultures, seven had negative cultures, and one patient had no cultures of the biopsy specimen. The patients with histologically and/or microbiologically proven osteomyelitis were correctly interpreted as true positive in the routine clinical reading of ¹⁸F-FDG PET images. There was no relationship between the level of ¹⁸F-FDG PET uptake and the presence of positive or negative bacterial cultures. The result favors the concept that that culture-negative cases of osteomyelitis are false-negative infections due to nonculturable microbes. ¹⁸F-FDG PET may help to confirm the presence of metabolically active infection in these patients and guide their appropriate treatment.

pH dependent silver nanoparticles releasing titanium implant: A novel therapeutic approach to control peri-implant infection

Peri-implant infection control is crucial for implant fixation and durability. Antimicrobial administration approaches to control peri-implant infection are far from satisfactory. During bacterial infection, pH level around the peri-implant surface decreases as low as pH 5.5. This change of pH can be used as a switch to control antimicrobial drug release from the implant surface. Silver nanoparticles (AgNPs) have broad-spectrum antimicrobial properties. In this study, we aimed to design a pH-dependent AgNPs releasing titania nanotube arrays (TNT) implant for peri-implant infection control. The nanotube arrays were fabricated on the surface of titanium implant as containers; AgNPs were grafted on TNT implant surface via a low pH-sensitive acetal linker (TNT-AL-AgNPs). SEM, TEM, AFM, FTIR as well as XPS data showed that AgNPs have been successfully linked to TNT via acetal linker without affecting the physicochemical characteristics of TNT. The pH 5.5 enhanced AgNPs release from TNT-AL-AgNPs implant compared with pH 7.4. AgNPs released at pH 5.5 robustly increased antimicrobial activities against gram-positive and gram-negative bacteria compared with AgNPs released at pH 7.4. TNT-AL-AgNPs implant enhanced osteoblast proliferation, differentiation, and did not affect osteoblast morphology in vitro. In conclusion, incorporation of AgNPs in TNT via acetal linker maintained the surface characteristics of TNT. TNT-AL-AgNPs implant was biocompatible to osteoblasts and showed osteoinductive properties. AgNPs were released from TNT-AL-AgNPs implant in high dose at pH 5.5, and this release showed strong antimicrobial properties in vitro. Therefore, this novel design of low pH-triggered AgNPs releasing TNT-AL-AgNPs could be an infection-triggered antimicrobial releasing implant model to control peri-implant infection.

Hyperoside inhibits biofilm formation of Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa) is a common pathogen in hospital-acquired infection and is readily able to form biofilms. Due to its high antibiotic resistance, traditional antibacterial treatments exert a limited effect on P. aeruginosa biofilm infections. It has been indicated that hyperoside inhibits P. aeruginosa PAO1 (PAO1) biofilm formation without affecting growth. Therefore, the current study examined the biofilm formation and quorum sensing (QS) system of PAO1 in the presence of hyperoside. Confocal laser scanning microscopy analysis demonstrated that hyperoside significantly inhibited biofilm formation. It was also observed that hyperoside inhibited twitching motility in addition to adhesion. Data from reverse transcription-quantitative polymerase chain reaction indicated that hyperoside inhibited the expression of lasR, lasI, rhlR and rhlI genes. These results suggest that the QS-inhibiting effect of hyperoside may lead to a reduction in biofilm formation. However, the precise mechanism of hyperoside on P. aeruginosa pathogenicity remains unclear and requires elucidation in additional studies.

Treatment of chronic orthopaedic infection

Chronic infections are one of the major challenges in orthopaedic surgery, both for surgeons and patients. They are characterised by obstinate persistency of the causing microorganisms and resulting long-term disablement of the patients, associated with remarkable costs for the health care system.

Difficulties derive from the biofilm-mode of living of pathogens with resistances against immunological defence and antimicrobial substances, and osseous defects resulting from the disease itself and surgical interventions.

Established techniques usually require multiple costly operations with extended periods of disablement and impairment of the patients, sometimes making the therapy worse than the disease.

Better understanding of the backgrounds of the conditions has led to new surgical techniques and differentiated application of antibiotics, aiming in improved quality of life for our patients.

Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160063. Originally published online at www.efortopenreviews.org

Halloysite clay nanotubes as effective nanocarriers for the adsorption and loading of vancomycin for sustained release

A simple and effective local drug delivery system with halloysite clay nanotubes as nanocarriers for vancomycin was prepared for the bacterial infection treatment.

Allograft Bone as Antibiotic Carrier

The treatment of chronic bone and joint infections is characterized by obstinate persistency of the causing microorganisms and resulting long term disability to patients, associated with remarkable costs for the health care system. Difficulties derive from biofilm formed on dead bone and eventual implants, with resistance against immunological defences and antimicrobial substances. Biofilm embedded bacteria require up to 1000 times the antibiotic concentration of planktonic bacteria for elimination. Systemic antibiotic treatment alone cannot provide the concentrations required and surgical intervention is always prerequisite for potentially providing a cure. A second issue is that osseous defects are almost always present after surgical debridement, and it is difficult to address their reconstruction. One option is to use bone grafts, either from the patient´s own body or from foreign donors (allografts). Grafts are usually unvascularized and are prone to colonization with bacteria. Loading of allografts with antibiotics may not only protect grafts from bacterial adhesion but, using appropriate processing methods, may also provide high local antibiotic concentrations that may eliminate remaining sessile pathogens. For efficient action as antibiotic carriers, the release of antibiotics should be above the minimum biofilm eradication concentration (MBEC) for a prolonged period of time. Cleaning the bone from bone marrow opens a large reservoir for storage of antimicrobial substances that, after implantation, may be released to the surrounding in a sustained mode, possibly eliminating remaining biofilm remnants. Removal of bone marrow, leaving a pure matrix, provides increased safety and improved revascularization of the graft. Local provision of antibiotic concentrations above the MBEC may enable simultaneous internal fixation with osteosynthetic material and single stage exchange of infected endoprostheses, resulting in shorter hospital stays with reduced pain and faster rehabilitation of patients.

Extracellular Bacterial Proteases in Chronic Wounds: A Potential Therapeutic Target?

Significance: Bacterial biofilms are considered to be responsible for over 80% of persistent infections, including chronic lung infections, osteomyelitis, periodontitis, endocarditis, and chronic wounds. Over 60% of chronic wounds are colonized with bacteria that reside within a biofilm. The exaggerated proteolytic environment of chronic wounds, more specifically elevated matrix metalloproteinases, is thought to be one of the possible reasons as to why chronic wounds fail to heal. However, the role of bacterial proteases within chronic wounds is not fully understood. Recent Advances: Recent research has shown that bacterial proteases can enable colonization and facilitate bacterial immune evasion. The inhibition of bacterial proteases such as Pseudomonas aeruginosa elastase B (LasB) has resulted in the disruption of the bacterial biofilm in vitro. P. aeruginosa is thought to be a key pathogen in chronic wound infection, and therefore, the disruption of these biofilms, potentially through the targeting of P. aeruginosa bacterial proteases, is an attractive therapeutic endeavor. Critical Issues: Disrupting biofilm formation through the inhibition of bacterial proteases may lead to the dissemination of bacteria from the biofilm, allowing planktonic cells to colonize new sites within the wound. Future Directions: Despite a plethora of evidence supporting the role of bacterial proteases as virulence factors in infection, there remains a distinct lack of research into the effect of bacterial proteases in chronic wounds. To assess the viability of targeting bacterial proteases, future research should aim to understand the role of these proteases in a variety of chronic wound subtypes.

Modeling and Re-Engineering of Azotobacter vinelandii Alginate Lyase to Enhance Its Catalytic Efficiency for Accelerating Biofilm Degradation

Alginate is known to prevent elimination of Pseudomonas aeruginosa biofilms. Alginate lyase (AlgL) might therefore facilitate treatment of Pseudomonas aeruginosa-infected cystic fibrosis patients. However, the catalytic activity of wild-type AlgL is not sufficiently high. Therefore, molecular modeling and site-directed mutagenesis of AlgL might assist in enzyme engineering for therapeutic development. AlgL, isolated from Azotobacter vinelandii, catalyzes depolymerization of alginate via a β-elimination reaction. AlgL was modeled based on the crystal structure template of Sphingomonas AlgL species A1-III. Based on this computational analysis, AlgL was subjected to site-directed mutagenesis to improve its catalytic activity. The kcat/Km of the K194E mutant showed a nearly 5-fold increase against the acetylated alginate substrate, as compared to the wild-type. Double and triple mutants (K194E/K245D, K245D/K319A, K194E/K245D/E312D, and K194E/K245D/K319A) were also prepared. The most potent mutant was observed to be K194E/K245D/K319A, which has a 10-fold improved kcat value (against acetylated alginate) compared to the wild-type enzyme. The antibiofilm effect of both AlgL forms was identified in combination with piperacillin/tazobactam (PT) and the disruption effect was significantly higher in mutant AlgL combined with PT than wild-type AlgL. However, for both the wild-type and K194E/K245D/K319A mutant, the use of the AlgL enzyme alone did not show significant antibiofilm effect.

Co-delivery of nitric oxide and antibiotic using polymeric nanoparticles

The rise of hospital-acquired infections, also known as nosocomial infections, is a growing concern in intensive healthcare, causing the death of hundreds of thousands of patients and costing billions of dollars worldwide every year. In addition, a decrease in the effectiveness of antibiotics caused by the emergence of drug resistance in pathogens living in biofilm communities poses a significant threat to our health system. The development of new therapeutic agents is urgently needed to overcome this challenge. We have developed new dual action polymeric nanoparticles capable of storing nitric oxide, which can provoke dispersal of biofilms into an antibiotic susceptible planktonic form, together with the aminoglycoside gentamicin, capable of killing the bacteria. The novelty of this work lies in the attachment of NO-releasing moiety to an existing clinically used drug, gentamicin. The nanoparticles were found to release both agents simultaneously and demonstrated synergistic effects, reducing the viability of Pseudomonas aeruginosa biofilm and planktonic cultures by more than 90% and 95%, respectively, while treatments with antibiotic or nitric oxide alone resulted in less than 20% decrease in biofilm viability.

Nanoparticles highly loaded with gentamicin sulfate by a combination of polyhydroxylated macromonomers and ROMP for the synthesis of bioactive biomaterials

Nanoparticles highly loaded with gentamicin sulfate were synthesized by ring-opening metathesis copolymerization in a dispersion of norbornene with modified polyhydroxylated macromonomers.

Infection in Orthopaedics

Infection in orthopaedic trauma patients is a common problem associated with significant financial and psychosocial costs, and increased morbidity. This review outlines technologies to diagnose and prevent orthopaedic infection, examines implant-related infection and its management, and discusses the treatment of post-traumatic osteomyelitis. The gold standard for diagnosing infection has a number of disadvantages, and thus new technologies to diagnose infection are being explored, including multilocus polymerase chain reaction with electrospray ionization-mass spectrometry and optical imaging. Numerous strategies have been employed to prevent orthopaedic infection, including use of antibiotic-impregnated implant coatings and cement; however, further research is required to optimize these technologies. Biofilm formation on orthopaedic implants is attributed to the glycocalyx-mediated surface mode of bacterial growth and is usually treated through a secondary surgery involving irrigation, debridement and the appropriate use of antibiotics, or complete removal of the infected implant. Research into the treatment of post-traumatic osteomyelitis has focused on developing an optimal local antibiotic delivery vehicle, such as antibiotic-impregnated polymethylmethacrylate (PMMA) cement beads or bioabsorbable bone substitute (BBS) delivery systems. As these new technologies to diagnose, prevent and treat orthopaedic infection advance, the incidence of infection will decrease and patient care will be optimized.

Biocompatibility of antibacterial Ti-Cu sintered alloy: in vivo bone response

Ti-10Cu sintered alloy has shown very strong in vitro and in vivo antibacterial property and in vitro cell compatibility. In this paper, Ti-10Cu implant (Ti-Cu group) and commercial pure Ti implant (cp-Ti group) were implanted in rabbit femurs to investigate in vivo bone response to the Ti-10Cu alloy. X-ray photo, fluorescent microscopy, routine pathological examination and immunohistochemistry have been used to analyze bone growth, mineral apposition rate (MAR), bone implant contact (BIC), BMP-2 expression and TGF-β1 expression. In both Ti-Cu and cp-Ti groups, new bone tissue was found at bone/implant interfaces 4 weeks postimplantation and completely filled the interfaces gap bone 12 weeks postimplantation. A significant MOD value in BMP-2 expression was observed at week 1 and week 4 in the Ti-Cu group with lower values of week 2 and 3 in both groups, which indicated strong positive activity. MOD value in TGF-β1 expression decreased with the extension of implantation. However, no difference can be found in MAR, BIC and TGF-β1 expression between the two groups at all intervals. It was deduced that Ti-Cu alloy exhibited as good bone response as cp-Ti. The good bone compatibility suggests that Ti-10Cu alloy might have potential application in orthopedic surgery and dental implant.

Can Near-infrared Spectroscopy Detect and Differentiate Implant-associated Biofilms?

BACKGROUND

Established bacterial diagnostic techniques for orthopaedic-related infections rely on a combination of imperfect tests that often can lead to negative culture results. Spectroscopy is a tool that potentially could aid in rapid detection and differentiation of bacteria in implant-associated infections.

QUESTIONS/PURPOSES

We asked: (1) Can principal component analysis explain variation in spectral curves for biofilm obtained from Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa? (2) What is the accuracy of Fourier transformed-near infrared (FT-NIR)/multivariate data analysis in identifying the specific species associated with biofilm?

METHODS

Three clinical isolates, S aureus, S epidermidis, and P aeruginosa were cultured to create biofilm on surgical grade stainless steel. At least 52 samples were analyzed per group using a FT-NIR spectrometer. Multivariate and principal component analyses were performed on the spectral data to allow for modeling and identification of the bacterial species.

RESULTS

Spectral analysis was able to correctly identify 86% (37/43) of S aureus, 89% (16/18) of S epidermidis, and 70% (28/40) of P aeruginosa samples with minimal error. Overall, models developed using spectral data preprocessed using a combination of standard normal variant and first-derivative transformations performed much better than models developed with the raw spectral data in discriminating between the three classes of bacteria because of its low Type 1 error and large intermodel distinction.

CONCLUSIONS

The use of spectroscopic methods to identify and classify bacterial biofilms on orthopaedic implant material is possible and improves with advanced modeling that can be obtained rapidly with little error. The sensitivity for identification was 97% for S aureus (95% CI, 88-99%), 100% for S epidermidis (95% CI, 95-100%), and 77% for P aeruginosa (95% CI, 65-86%). The specificity of the S aureus was 86% (95% CI, 3-93%), S epidermidis was 89% (95% CI, 67-97%), and P aeruginosa was 70% (95% CI, 55-82%).

CLINICAL RELEVANCE

This technique of spectral data acquisition and advanced modeling should continue to be explored as a method for bacterial biofilm identification. A spectral databank of bacterial and potentially contaminating tissues should be acquired initially through an in vivo animal model and quickly transition to explanted devices and the clinical arena.

Hierarchical micro/nanostructured titanium with balanced actions to bacterial and mammalian cells for dental implants

A versatile strategy to endow dental implants with long-term antibacterial ability without compromising the cytocompatibility is highly desirable to combat implant-related infection. Silver nanoparticles (Ag NPs) have been utilized as a highly effective and broad-spectrum antibacterial agent for surface modification of biomedical devices. However, the high mobility and subsequent hazardous effects of the particles on mammalian cells may limit its practical applications. Thus, Ag NPs were immobilized on the surface of sand-blasted, large grit, and acid-etched (SLA) titanium by manipulating the atomic-scale heating effect of silver plasma immersion ion implantation. The silver plasma immersion ion implantation-treated SLA surface gave rise to both good antibacterial activity and excellent compatibility with mammalian cells. The antibacterial activity rendered by the immobilized Ag NPs was assessed using Fusobacterium nucleatum and Staphylococcus aureus, commonly suspected pathogens for peri-implant disease. The immobilized Ag NPs offered a good defense against multiple cycles of bacteria attack in both F. nucleatum and S. aureus, and the mechanism was independent of silver release. F. nucleatum showed a higher susceptibility to Ag NPs than S. aureus, which might be explained by the presence of different wall structures. Moreover, the immobilized Ag NPs had no apparent toxic influence on the viability, proliferation, and differentiation of rat bone marrow mesenchymal stem cells. These results demonstrated that good bactericidal activity could be obtained with very small quantities of immobilized Ag NPs, which were not detrimental to the mammalian cells involved in the osseointegration process, and promising for titanium-based dental implants with commercial SLA surfaces.

A review of telavancin activity in in vitro biofilms and animal models of biofilm-associated infections

ABSTRACT 

Tissue- and device-associated biofilm infections are important medical problems. These infections are difficult to treat due to a high-level of tolerance to antibiotics. Telavancin has been studied in several in vitro biofilm models and has demonstrated efficacy against staphylococcal and enterococcal-associated biofilm infections, including those formed by methicillin-resistant Staphylococcus aureus. Telavancin was effective against the difficult-to-treat vancomycin- and glycopeptide-intermediate strains of S. aureus in these models. Furthermore, the efficacy of telavancin has been evaluated in several biofilm-related in vivo models, including osteomyelitis, endocarditis and device-associated infections in rabbits. Overall, telavancin exhibited similar or greater efficacy than vancomycin and other comparators in these animal models and maintained activity against vancomycin-intermediate and daptomycin nonsusceptible strains of S. aureus.

Antimicrobial and osteogenic properties of silver-ion-implanted stainless steel

Prevention of implant loosening and infection is crucial to orthopedic and dental surgeries. In this work, the surface of stainless steel (SS) was modified by silver-sourced plasma immersion ion implantation (Ag-PIII). Metallic silver nanoparticles with various diameters and distributions were fabricated on the SS surfaces after treatment with Ag-PIII for 0.5 and 1.5 h, respectively. The osteogenic activity and antimicrobial properties of SS before and after Ag-PIII treatment were evaluated using in vitro and in vivo tests. The results demonstrated that Ag-PIII treatment not only promoted the antibacterial activity of SS but also enhanced the osteogenic differentiation of human bone marrow stromal cells.

Antimicrobial resistance, respiratory tract infections and role of biofilms in lung infections in cystic fibrosis patients

Lung infection is the main cause of morbidity and mortality in patients with cystic fibrosis and is mainly dominated by Pseudomonas aeruginosa. The biofilm mode of growth makes eradication of the infection impossible, and it causes a chronic inflammation in the airways. The general mechanisms of biofilm formation and antimicrobial tolerance and resistance are reviewed. Potential anti-biofilm therapeutic targets such as weakening of biofilms by quorum-sensing inhibitors or antibiotic killing guided by pharmacokinetics and pharmacodynamics of antibiotics are presented. The vicious circle of adaptive evolution of the persisting bacteria imposes important therapeutic challenges and requires development of new drug delivery systems able to reach the different niches occupied by the bacteria in the lung of cystic fibrosis patients.

Anti-biofilm properties of magnesium metal via alkaline pH

Mg prevents bacteria biofilm formationviahigh alkalinity at its surface rather than by high Mg ion concentration.

Bacillus amyloliquefaciens-secreted cyclic dipeptide – cyclo(l-leucyl-l-prolyl) inhibits biofilm and virulence production in methicillin-resistant Staphylococcus aureus

The current study explores the inhibitory efficacy of cyclo(l-leucyl-l-prolyl) (CLP), a cyclic dipeptide fromBacillus amyloliquefacienson the biofilm and virulence production of methicillin-resistantStaphylococcus aureus(MRSA).

High complication rate after septic orthopaedic implant removal of the lower leg

INTRODUCTION

The aim of the study was to determine predictive risk factors for revision surgery in patients with septic orthopaedic implant removal of the lower leg.

MATERIALS AND METHODS

A total of 196 patients with septic removal of orthopaedic implants after primary trauma of the lower leg between 2008 and 2012 were evaluated. Patients with endoprosthesis infection were excluded from this study.

RESULTS

Thirteen patients (22.4 %) had infectious complications with revision surgery. We found 14 patients with soft tissue infections, 10 patients with osteomyelitis, 19 patients with wound-healing problems, 10 patients with pin track infections and two patients with fistulas. High complication rates were associated with severity of the initial trauma, localisation, and the state of union or non-union. Patients with peripheral arterial disease, anaemia and smoking showed a significantly higher risk for revision surgery; whereas patients with diabetes and arterial hypertension did not. A total of 22.6 % had open fractures as an initial trauma. In 76 %, bacteria could be detected. The complication rate was 41.2 % after initial open fractures and 19.6 % after initial closed fractures. A higher grade of soft tissue damage showed no increasing complication rate (p > 0.05).

CONCLUSIONS

In this study, complications after septic implant removal of the lower leg were evaluated and risk factors were determined. The awareness of the risks for complications after septic orthopaedic implant removal can lead to a better treatment for patients. Decision-making can be based on scientific results to prevent patients suffering from further severe disease progression.