Z-form extracellular DNA is a structural component of the bacterial biofilm matrix.

Biofilms are community architectures adopted by bacteria inclusive of a self-formed extracellular matrix that protects resident bacteria from diverse environmental stresses and, in many species, incorporates extracellular DNA (eDNA) and DNABII proteins for structural integrity throughout biofilm development. Here, we present evidence that this eDNA-based architecture relies on the rare Z-form. Z-form DNA accumulates as biofilms mature and, through stabilization by the DNABII proteins, confers structural integrity to the biofilm matrix. Indeed, substances known to drive B-DNA into Z-DNA promoted biofilm formation whereas those that drive Z-DNA into B-DNA disrupted extant biofilms. Importantly, we demonstrated that the universal bacterial DNABII family of proteins stabilizes both bacterial- and host-eDNA in the Z-form in situ. A model is proposed that incorporates the role of Z-DNA in biofilm pathogenesis, innate immune response, and immune evasion.

Editorial Commentary: Low-Grade Infections May Contribute to Anterior Cruciate Ligament Reconstruction Graft Failure.

The etiology of anterior cruciate ligament (ACL) reconstruction failure is often multifactorial, and the role of subclinical bacterial colonization in ACL reconstruction failure has not been fully elucidated. Although the presence of bacterial metabolism in and of itself does not indicate true clinical infection, low-grade infections may contribute to ACL reconstruction graft failure. Bacterial biofilms on soft tissue grafts are shown to change the crimp patterns of collagen and lower graft load to failure. In addition, bacterial DNA has been reported in 80-87% of failed ACL grafts during revision surgery compared to only 20% of primary ACL grafts. Also, higher bacterial DNA concentration is associated with tibial tunnel widening. Further study is needed to establish if any causal relationship between bacterial colonization and ACL graft failure exists. But it does seem that the circumstantial evidence is pointing to such a relationship.

In Vitro Staphylococcal Aggregate Morphology and Protection from Antibiotics Are Dependent on Distinct Mechanisms Arising from Postsurgical Joint Components and Fluid Motion.

Considerable progress has been made toward elucidating the mechanism of Staphylococcus aureus aggregation in synovial fluid. In this study, aggregate morphology was assessed following incubation under several simulated postsurgical joint conditions. Using fluorescently labeled synovial fluid polymers, we show that aggregation occurs through two distinct mechanisms: (i) direct bridging between S. aureus cells and host fibrinogen and (ii) an entropy-driven depletion mechanism facilitated by hyaluronic acid and albumin. By screening surface adhesin-deficient mutants (clfA, clfB, fnbB, and fnbA), we identified the primary genetic determinant of aggregation in synovial fluid to be clumping factor A. To characterize this bridging interaction, we employed an atomic force microscopy-based approach to quantify the binding affinity of either wild-type S. aureus or the adhesin mutant to immobilized fibrinogen. Surprisingly, we found there to be cell-to-cell variability in the binding strength of the bacteria for immobilized fibrinogen. Superhigh-resolution microscopy imaging revealed that fibrinogen binding to the cell wall is heterogeneously distributed at both the single cell and population levels. Finally, we assessed the antibiotic tolerance of various aggregate morphologies arising from newly deciphered mechanisms of polymer-mediated synovial fluid-induced aggregation. The formation of macroscopic aggregates under shear was highly tolerant of gentamicin, while smaller aggregates, formed under static conditions, were susceptible. We hypothesize that aggregate formation in the joint cavity, in combination with shear, is mediated by both polymer-mediated aggregation mechanisms, with depletion forces enhancing the stability of essential bridging interactions. IMPORTANCE The formation of a bacterial biofilm in the postsurgical joint environment significantly complicates the resolution of an infection. To form a resilient biofilm, incoming bacteria must first survive the initial invasion of the joint space. We previously found that synovial fluid induces the formation of Staphylococcus aureus aggregates, which may provide rapid protection during the early stages of infection. The state of the host joint environment, including the presence of fluid flow and fluctuating abundance of synovial fluid polymers, determines the rate and size of aggregate formation. By expanding on our knowledge of the mechanism and pathogenic implications of synovial fluid-induced aggregation, we hope to contribute insights for the development of novel methods of prevention and therapeutic intervention.

Effects of biofilm heterogeneity on the apparent mechanical properties obtained by shear rheometry.

Rheometry is an experimental technique widely used to determine the mechanical properties of biofilms. However, it characterizes the bulk mechanical behavior of the whole biofilm. The effects of biofilm mechanical heterogeneity on rheometry measurements are not known. We used laboratory experiments and computer modeling to explore the effects of biofilm mechanical heterogeneity on the results obtained by rheometry. A synthetic biofilm with layered mechanical properties was studied, and a viscoelastic biofilm theory was employed using the Kelvin-Voigt model. Agar gels with different concentrations were used to prepare the layered, heterogeneous biofilm, which was characterized for mechanical properties in shear mode with a rheometer. Both experiments and simulations indicated that the biofilm properties from rheometry were strongly biased by the weakest portion of the biofilm. The simulation results using linearly stratified mechanical properties from a previous study also showed that the weaker portions of the biofilm dominated the mechanical properties in creep tests. We note that the model can be used as a predictive tool to explore the mechanical behavior of complex biofilm structures beyond those accessible to experiments. Since most biofilms display some degree of mechanical heterogeneity, our results suggest caution should be used in the interpretation of rheometry data. It does not necessarily provide the "average" mechanical properties of the entire biofilm if the mechanical properties are stratified.

Surface properties influence marine biofilm rheology, with implications for ship drag.

Marine biofilms on ship hulls increase frictional drag, which has economic and environmental consequences. It is hypothesised that biofilm mechanics, such as viscoelasticity, play a critical role in biofilm-associated drag, yet is a poorly studied area. The current study aimed to rheologically characterise ship-relevant marine biofilms. To combat marine biofilms on ship hulls, fouling-control coatings are often applied; therefore, the effect of different surfaces on marine biofilm mechanics was also investigated. Three surfaces were tested: a non-biocidal, chemically inert foul-release coating (FRC), an inert primer (ACP) and inert PVC. Physical properties of biofilms were explored using Optical Coherence Tomography (OCT) and a parallel-plate rheometer was used for rheological testing. Image analysis revealed differences in the thickness, roughness, and percent coverage between the different biofilms. Rheological testing showed that marine biofilms, grown on FRC and ACP acted as viscoelastic materials, although there were differences. FRC biofilms had a lower shear modulus, a higher viscosity, and a higher yield stress than the ACP biofilms, suggesting that the FRC biofilms were more readily deformable but potentially more robust. The results confirmed that surface treatment influences the structural and mechanical properties of ship-relevant marine biofilms, which could have implications for drag. A better understanding of how different surface treatments affect marine biofilm rheology is required to improve our knowledge on biofilm fluid-structure interactions and to better inform the coating industry of strategies to control biofilm formation and reduce drag.

Exploration of the Pharmacodynamics for Pseudomonas aeruginosa Biofilm Eradication by Tobramycin.

Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen which is involved in numerous infections. It is of growing concern within the field of antibiotic resistance and tolerance and often exhibits multidrug resistance. Previous studies have shown the emergence of antibiotic-resistant and -tolerant variants within the zone of clearance of a biofilm lawn after exposure to aminoglycosides. As concerning as the tolerant variant emergence is, there was also a zone of killing (ZOK) immediately surrounding the antibiotic source from which no detectable bacteria emerged or were cultured. In this study, the ZOK was analyzed using both in vitro and in silico methods to determine if there was a consistent antibiotic concentration versus time constraint (area under the curve [AUC]) which is able to completely kill all bacteria in the lawn biofilms in our in vitro model. Our studies revealed that by achieving an average AUC of 4,372.5 µg·h/mL, complete eradication of biofilms grown on both agar and hydroxyapatite was possible. These findings show that appropriate antibiotic concentrations and treatment duration may be able to treat antibiotic-resistant and -tolerant biofilm infections.

The Influence of Patterned Surface Features on the Accumulation of Bovine Synovial Fluid-Induced Aggregates of Staphylococcus aureus.

Periprosthetic joint infection (PJI) after joint replacement is a major clinical issue requiring multiple surgeries and antibiotic interventions. Recent in vitro research has shown that PJI staphylococcal strains rapidly form antibiotic-resistant free-floating aggregates in the presence of bovine synovial fluid (BSF). Staphylococcal aggregates are also present in human PJI joint fluid. However, the influence of surface roughness and fluid shear on the attachment and retention of such aggregates on surfaces is not known. Our aim was to assess how surface roughness and fluid shear stress influenced the attachment and retention of Staphylococcus aureus BSF-mediated aggregates on smooth- and rough-patterned titanium in flow cells compared to nonaggregated cells. The attachment of S. aureus aggregates was significantly greater than that of single cells but was independent of surface roughness; however, on the patterned surfaces, aggregates preferentially accumulated in the grooves. Fibrous components in the BSF were also colocalized with the grooves. After a 24-h attachment-and-incubation period, different shear stresses were applied. There was significant detachment from flat surfaces at a flow rate of 1 mL/min (τw = 0.0012 Pa) but minimal detachment from the patterned surfaces, even at flow rates as high as 13.9 mL/min (τw = 0.0169 Pa). The retention of bacterial aggregates and biofilms on rough surfaces exposed to shear might be an important consideration for the location of colonization on orthopedic implants, which can have wide ranges of roughness and surface features and can influence the efficacy of shear-based debridement methods such as pulse lavage. IMPORTANCE Periprosthetic joint infections occurring after joint replacement are a major clinical problem requiring repeated surgeries and antibiotic interventions. Staphylococcus aureus is the most prominent bacterium causing most implant-related infections. S. aureus can form a biofilm, which is defined as a group of attached bacteria with the formation of an envelope that is resistant to antibiotics. The attachment and retention of these bacteria on implant surfaces are not clearly understood. Recent in vitro research investigations have shown that staphylococcal strains rapidly form aggregates in the presence of bovine synovial fluid (BSF) in the joints, which allows bacteria time to attach to the implant surface, leading to biofilm formation. Thus, in this study, we examined the attachment of aggregates on titanium surfaces with varying roughnesses and found robust bacterial attachment and retention along the ridges and grooves, which colocalized with the deposition of fibrous components present in the BSF.

Coupled CFD-DEM modeling to predict how EPS affects bacterial biofilm deformation, recovery and detachment under flow conditions.

The deformation and detachment of bacterial biofilm are related to the structural and mechanical properties of the biofilm itself. Extracellular polymeric substances (EPS) play an important role on keeping the mechanical stability of biofilms. The understanding of biofilm mechanics and detachment can help to reveal biofilm survival mechanisms under fluid shear and provide insight about what flows might be needed to remove biofilm in a cleaning cycle or for a ship to remove biofilms. However, how the EPS may affect biofilm mechanics and its deformation in flow conditions remains elusive. To address this, a coupled computational fluid dynamic- discrete element method (CFD-DEM) model was developed. The mechanisms of biofilm detachment, such as erosion and sloughing have been revealed by imposing hydrodynamic fluid flow at different velocities and loading rates. The model, which also allows adjustment of the proportion of different functional groups of microorganisms in the biofilm, enables the study of the contribution of EPS toward biofilm resistance to fluid shear stress. Furthermore, the stress-strain curves during biofilm deformation have been captured by loading and unloading fluid shear stress to study the viscoelastic properties of the biofilm. Our predicted emergent viscoelastic properties of biofilms were consistent with relevant experimental measurements.

A commercial SnF2 toothpaste formulation reduces simulated human plaque biofilm in a dynamic typodont model.

AIMS: We present a dynamic typodont biofilm model (DTBM) incorporating (1) human dentition anatomy, (2) fluid flow over intermittently fluid bathed tooth surfaces and (3) an oxic headspace to allow aerobic and anaerobic niches to develop naturally, as a screening tool to assess the effect of stannous fluoride (SnF2 ) toothpaste against a simulated human plaque biofilm (SPB). METHODS AND RESULTS: First, hydroxyapatite (HA) coupons were inoculated with human saliva/plaque and cultured at 37°C under air. Selected species representative of common commensal and anaerobic pathogens were quantified for relative abundance changes over 4 days by PCR densitometry to confirm the culture conditions allowed the proliferation of these species. A continuous culture DTBM reactor on a rocker table was inoculated with saliva/plaque and incubated at 37°C for 24 h. Tooth shear stress was estimated by particle tracking. A SnF2 toothpaste solution, or a sham rise was administered twice daily for 3 days to mimic routine oral hygiene. SPB biomass was assessed by total bacterial DNA and methylene blue (MB) staining. Early colonizer aerobes and late colonizer anaerobes species were detected in the HA and DTBM, and the trends in changing abundance were consistent with those seen clinically. CONCLUSIONS: Treatment with the SnF2 solution showed significant reductions of 53.05% and 54.4% in the SPB by MB staining and DNA, respectively. SIGNIFICANCE AND IMPACT OF STUDY: The model has potential for assessing dentition anatomy and fluid flow on the efficacy of antimicrobial efficacy against localized SPB and may be amenable to the plaque index clinical evaluation.

Development of a professional competency framework for Australian sonographers-perspectives for developing competencies using a Delphi methodology.

BACKGROUND: Professional competencies are important for enhancing alignment between the needs of education, industry and health consumers, whilst describing public expectations around health professionals. The development of competency standards for the sonography profession defines the behaviours, skills and knowledge sonographers should demonstrate for each learning and experience level. OBJECTIVE: The objective of this project was to develop a set of professional competency standards for the sonography profession which described in depth the behaviours, skills and knowledge sonographers should demonstrate across multiple learning and experience levels. METHODS: Representatives of three Australian ultrasound professional associations and seven tertiary institutions involved in entry-level sonographer education in Australia formed a research team (RT). The RT recruited an expert panel that responded to six survey rounds. Using a Delphi methodology, the results and free-text comments from each previous round were fed back to participants in the subsequent survey rounds to achieve a consensus. RESULTS: The project developed a professional competency framework for sonographers, which included four major domains: detailed competency standards, sonographer knowledge, sonographer attitudes and a holistic competency matrix [https://doi.org/10.6084/m9.figshare.17148035.v2.]. CONCLUSION: The Delphi methodology is an effective way to develop professional competency standards. This paper describes the methods and challenges in developing such standards for sonographers which could be translated to other health professionals.

The extracellular DNA lattice of bacterial biofilms is structurally related to Holliday junction recombination intermediates.

Extracellular DNA (eDNA) is a critical component of the extracellular matrix of bacterial biofilms that protects the resident bacteria from environmental hazards, which includes imparting significantly greater resistance to antibiotics and host immune effectors. eDNA is organized into a lattice-like structure, stabilized by the DNABII family of proteins, known to have high affinity and specificity for Holliday junctions (HJs). Accordingly, we demonstrated that the branched eDNA structures present within the biofilms formed by NTHI in the middle ear of the chinchilla in an experimental otitis media model, and in sputum samples recovered from cystic fibrosis patients that contain multiple mixed bacterial species, possess an HJ-like configuration. Next, we showed that the prototypic Escherichia coli HJ-specific DNA-binding protein RuvA could be functionally exchanged for DNABII proteins in the stabilization of biofilms formed by 3 diverse human pathogens, uropathogenic E. coli, nontypeable Haemophilus influenzae, and Staphylococcus epidermidis Importantly, while replacement of DNABII proteins within the NTHI biofilm matrix with RuvA was shown to retain similar mechanical properties when compared to the control NTHI biofilm structure, we also demonstrated that biofilm eDNA matrices stabilized by RuvA could be subsequently undermined upon addition of the HJ resolvase complex, RuvABC, which resulted in significant biofilm disruption. Collectively, our data suggested that nature has recapitulated a functional equivalent of the HJ recombination intermediate to maintain the structural integrity of bacterial biofilms.

Implant surface culture may be a useful adjunct to standard tissue sampling culture for identification of pathogens accounting for fracture-device-related infection: a within-person randomized agreement study of 42 patients.

BACKGROUND AND PURPOSE: Identification of pathogens causing fracture-device-related infection (FDRI) is always a challenge as the positive rate of standard tissue sampling culture (TSC) remains unsatisfactory. This study evaluates the efficiency of implant surface culture (ISC) as an adjunct to standard TSC for identification of FDRI-associated microorganisms. PATIENTS AND METHODS: Between November 2020 and March 2022, patients diagnosed with FDRI defined by the International Fracture-Related Infection (FRI) Consensus Group, and indicated for implant removal, underwent both methods for bacteria detection. The test order of ISC and TSC was randomly selected for each patient included, as a within-person randomized design. For ISC, the recovered implants were gently covered with tryptic soy agar after rinsing with normal saline twice, and then incubated at 37℃ 5% CO2 for up to 14 days. For TSC, 5 specimens were sampled and sent to the Clinical Laboratory of Southern Medical University Nanfang Hospital, Guangzhou, for culture and identification. RESULTS: 42 consecutive patients were included, with a mean age of 46 years. The most frequent infection site and implant type were the tibia (21 cases) and plates with screws (30 cases), respectively. Altogether 21 patients were found with positive outcomes by both methods, and the identified pathogens were consistent. ISC found an additional 15 patients showing positive results, which were negative by TSC. Furthermore, the mean culture time of ISC was shorter than that of TSC (1.5 days vs. 3.2 days). INTERPRETATION: ISC may be a useful adjunct to TSC for detection of bacteria causing FDRI, with a relatively higher positive rate and a shorter culture time.

A rapid benchtop method to assess biofilm on marine fouling control coatings.

A rapid benchtop method to measure the torque associated with minidiscs rotating in water using a sensitive analytical rheometer has been used to monitor the drag caused by marine fouling on coated discs. The method was calibrated using sandpaper surfaces of known roughness. Minidiscs coated with commercial fouling control coatings, plus an inactive control, were exposed in an estuarine harbour. After 176 days the drag on the fouling control-coated discs, expressed as a moment coefficient, was between 73% and 90% less than the drag on the control coating. The method has potential use as a screen for novel antifouling and drag reducing coatings and surfaces. Roughness functions derived using Granville's indirect similarity law are similar to patterns found in the general hydrodynamics literature, and so rotational minidisc results can be considered with reference to other fouling drag datasets.Supplemental data for this article is available online at https://doi.org/10.1080/08927014.2021.1929937 .

Synovial Fluid Mediated Aggregation of Clinical Strains of Four Enterobacterial Species.

Septic arthritis and prosthetic joint infection (PJI) are conditions commonly associated with Gram-positive cocci, however, a drastic increase in cases derived from enterobacterial species has been observed. Recently it has been reported by multiple groups that staphylococci rapidly form free-floating aggregates in the presence of synovial fluid. These aggregates are comparatively more resistant to antimicrobial challenge than their planktonic counterparts, and thus may play a role in the pathogenesis of joint infection. While staphylococcal aggregates have been the primary focus of interest in the field, it is unclear just how widespread synovial fluid mediated aggregation (SFMA) is in Gram negative enterobacteria (GNE). Through this work we have evaluated SFMA in clinical GNE isolated from PJIs. Two PJI clinical strains each of Enterobacter cloacae, Escherichia coli, Klebsiella pneumonia and Proteus mirabilis strains representing a range of antibiotic susceptibilities were exposed to 10% bovine synovial fluid supernatant (BSF) using a relatively simple, quick semi-quantitative method using an imaging plate reader. BSF stimulated aggregation within 0.5 h both strains of E. cloacae and P. mirabilis and one strain of E.coli. In one strain of P. mirabilis and E.coli, the size of the aggregates significantly increased from 0.5 to 2 h exposure. In contrast, neither K. pneumoniae strain aggregated in BSF. These preliminary findings show that aggregation can occur quickly in GNE, but the extent appears strain and species specific. Further work is required to assess the impact of SFMA on antibiotic tolerance, host innate immunity and the establishment of biofilms.

Laser tongue debridement for oral malodor-A novel approach to halitosis.

STUDY OBJECTIVE: Malodor is a multifactorial condition with oral pathology representing the main culprit and the tongue being the first to second contributor to the malodor. Bacterial load can represent a quantifiable measure regardless of the original pathology. We hypothesize that reduction in malodor can be represented by tongue changes both in appearance, bacterial and biofilm load reduction (measured by CFU and volatile gases measurement), organoleptic measurement and subjective improvement. METHODS: A randomized controlled prospective study under IRB approval. Diagnostic criteria for enrollment and follow up were organoleptic test by 2 judges, Halimeter reading, tongue colors changes HALT questionnaire and direct aerobic and anaerobic tongue cultures measured by CFU. Patients were treated with laser tongue debridement (LTD) with an Er,Cr:YSGG solid state laser has been shown to be effective in biofilm reduction. RESULTS: 54 patients recruited with 35 available for follow up. Improvement was observed on all objective and QOL subjective parameters. Treatment was tolerated well with minimal discomfort. CONCLUSIONS: The tongue is proven to be a major contributor to oral malodor and must be addressed in treatment protocol. LTD significantly reduces malodor by subjective and objective criteria. While impossible to determine whether the tongue serves as a bacterial reservoir or is the origin for oral bacteria it is clear that LTD improves oral hygiene and reduces malodor. LTD is safe and easy to perform. We encourage LTD to be a crucial part of any oral malodor treatment protocol. TRIAL REGISTRATION: clinical trials, NCT04120948. Registered 25 September 2019 - Retrospectively registered, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S00098SX&selectaction=Edit&uid=U0000W0Y&ts=51&cx=-elnx7e.

Novel Aminoglycoside-Tolerant Phoenix Colony Variants of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is an opportunistic bacterial pathogen and is known to produce biofilms. We previously showed the emergence of colony variants in the presence of tobramycin-loaded calcium sulfate beads. In this study, we characterized the variant colonies, which survived the antibiotic treatment, and identified three distinct phenotypes-classically resistant colonies, viable but nonculturable colonies (VBNC), and phoenix colonies. Phoenix colonies, described here for the first time, grow out of the zone of clearance of antibiotic-loaded beads from lawn biofilms while there are still very high concentrations of antibiotic present, suggesting an antibiotic-resistant phenotype. However, upon subculturing of these isolates, phoenix colonies return to wild-type levels of antibiotic susceptibility. Compared with the wild type, phoenix colonies are morphologically similar aside from a deficiency in green pigmentation. Phoenix colonies do not recapitulate the phenotype of any previously described mechanisms of resistance, tolerance, or persistence and, thus, form a novel group with their own phenotype. Growth under anaerobic conditions suggests that an alternative metabolism could lead to the formation of phoenix colonies. These findings suggest that phoenix colonies could emerge in response to antibiotic therapies and lead to recurrent or persistent infections, particularly within biofilms where microaerobic or anaerobic environments are present.

Staphylococcus aureus Aggregates on Orthopedic Materials under Varying Levels of Shear Stress.

Periprosthetic joint infection (PJI) occurring after artificial joint replacement is a major clinical issue requiring multiple surgeries and antibiotic interventions. Staphylococcus aureus is the bacterium most commonly responsible for PJI. Recent in vitro research has shown that staphylococcal strains rapidly form aggregates in the presence of synovial fluid (SF). We hypothesize that these aggregates provide early protection to bacteria entering the wound site, allowing them time to attach to the implant surface, leading to biofilm formation. Thus, understanding the attachment kinetics of these aggregates is critical in understanding their adhesion to various biomaterial surfaces. In this study, the number, size, and surface area coverage of aggregates as well as of single cells of S. aureus were quantified under various conditions on different orthopedic materials relevant to orthopedic surgery: stainless steel (316L), titanium (Ti), hydroxyapatite (HA), and polyethylene (PE). It was observed that, regardless of the material type, SF-induced aggregation resulted in reduced aggregate surface attachment and greater aggregate size than the single-cell populations under various shear stresses. Additionally, the surface area coverage of bacterial aggregates on PE was relatively high compared to that on other materials, which could potentially be due to the rougher surface of PE. Furthermore, increasing shear stress to 78 mPa decreased aggregate attachment to Ti and HA while increasing the aggregates' average size. Therefore, this study demonstrates that SF induced inhibition of aggregate attachment to all materials, suggesting that biofilm formation is initiated by lodging of aggregates on the surface features of implants and host tissues.IMPORTANCE Periprosthetic joint infection occurring after artificial joint replacement is a major clinical issue that require repeated surgeries and antibiotic interventions. Unfortunately, 26% of patients die within 5 years of developing these infections. Staphylococcus aureus is the bacterium most commonly responsible for this problem and can form biofilms to provide protection from antibiotics as well as the immune system. Although biofilms are evident on the infected implants, it is unclear how these are attached to the surface in the first place. Recent in vitro investigations have shown that staphylococcal strains rapidly form aggregates in the presence of synovial fluid and provide protection to bacteria, thus allowing them time to attach to the implant surface, leading to biofilm formation. In this study, we investigated the attachment kinetics of Staphylococcus aureus aggregates on different orthopedic materials. The information presented in this article will be useful in surgical management and implant design.

Printed Electroceutical Dressings for the Inhibition of Biofilms and Treatment of Chronic Wounds.

We report on an innovative, fabric-based conformable, and easily fabricated electroceutical wound dressing that inhibits bacterial biofilm infections and shows significant promise for healing chronic wounds. Cyclic voltammetry demonstrates the ability of the electroceutical to produce reactive oxygen species, primarily HOCl that is responsible for bacterial inhibition. In vitro investigation with the lawn biofilm grown on a soft tissue mimic assay shows the efficacy of the dressing against both gram-positive and gram-negative bacteria in the biofilm form. In vivo, the printed electroceutical dressing was utilized as an intervention treatment for a canine subject with a non-healing wound due to a year-long persistent polymicrobial infection. The clinical case study with the canine subject exhibited the applicability in a clinical setting with the results showing infection inhibition within 11 days of initial treatment. This printed electroceutical dressing was integrated with a Bluetooth® enabled circuit allowing remote monitoring of the current flow within the wound bed. The potential to monitor wounds remotely in real-time with a Bluetooth® enabled circuit proposes a new physical biomarker for management of infected, chronic wounds.

Infection in Arthroplasty: The Basic Science of Bacterial Biofilms in Its Pathogenesis, Diagnosis, Treatment, and Prevention.

In the past, the diagnosis and treatment of periprosthetic joint infection (PJI) in joint arthroplasty has often been frustrating for orthopaedic surgeons. The application of certain diagnostic criteria and different treatment strategies can be better directed if these infections are placed in the context of microbial biofilms. An understanding of this biofilm mode of microbial infection can help to explain the phenomenon of culture-negative infection as well as provide an understanding of why certain treatment modalities often fail. Continued basic research into the role of biofilms in infection will likely provide improved strategies for the clinical diagnosis and treatment of PJI. This is a review of the current preclinical knowledge of biofilm in relation to PJI with an overview of current practices applied in the diagnosis, treatment, and prevention of biofilm formation in this setting.

Use of an oxygen planar optode to assess the effect of high velocity microsprays on oxygen penetration in a human dental biofilms in-vitro.

BACKGROUND: Dental plaque biofilms are the causative agents of caries, gingivitis and periodontitis. Both mechanical and chemical strategies are used in routine oral hygiene strategies to reduce plaque build-up. If allowed to mature biofilms can create anoxic microenvironments leading to communities which harbor pathogenic Gram-negative anaerobes. When subjected to high velocity fluid jets and sprays biofilms can be fluidized which disrupts the biofilm structure and allows the more efficient delivery of antimicrobial agents. METHODS: To investigate how such jets may disrupt anoxic niches in the biofilm, we used planar optodes to measure the dissolved oxygen (DO) concentration at the base of in-vitro biofilms grown from human saliva and dental plaque. These biofilms were subject to "shooting" treatments with a commercial high velocity microspray (HVM) device. RESULTS: HVM treatment resulted in removal of much of the biofilm and a concurrent rapid shift from anoxic to oxic conditions at the base of the surrounding biofilm. We also assessed the impact of HVM treatment on the microbial community by tracking 7 target species by qPCR. There was a general reduction in copy numbers of the universal 16S RNA by approximately 95%, and changes of individual species in the target region ranged from approximately 1 to 4 log reductions. CONCLUSION: We concluded that high velocity microsprays removed a sufficient amount of biofilm to disrupt the anoxic region at the biofilm-surface interface.