Periprosthetic bacterial biofilm and quorum sensing

Comparison of antimicrobial efficacy and therapeutic index properties for common wound cleansing solutions, focusing on solutions containing PHMB

Background

Surgical site infections (SSIs) have been shown to increase patient morbidity and mortality, impact on quality of life and place a significant economic burden on healthcare systems worldwide. Irrigation using wound cleansing and antiseptic effective solutions during surgical procedures is a key part of SSI prevention. The optimal solution would have minimal cytotoxicity to the patient while maintaining a minimum concentration required for antimicrobial activity necessary to prevent opportunistic pathogens and biofilm formation.

Method

A variety of common wound irrigation products, including polyhexanide in various concentrations and compositions, iodine and hypochlorous acid-based solutions, were tested and compared for their activity against pathogens according to the ESKAPE group of nosocomial relevant microbes. The antimicrobial efficacy of the solutions was tested against planktonic cells using a time-kill assay. Its minimal bactericidal concentration (MBC) and its cytotoxicity against mouse fibroblast cells were determined. Finally, the Therapeutic Index (TI) was compared and the biofilm activity of a selected solution containing 0.1% polyhexanide (PHMB) was tested.

Results

Irrigation solutions containing 0.1% PHMB demonstrated rapid inactivation against planktonic cultures, achieving >4 lg reduction within 60 seconds. When comparing the TI of all irrigation solutions tested, the combination of 0.1% PHMB and poloxamer as an additive showed the best results in killing nosocomial pathogens and also to be less cytotoxic to mammalian fibroblasts, as demonstrated for PREVENTIA® Surgical Irrigation. When exposed to five single-species biofilms, PREVENTIA® Surgical Irrigation showed a 3 lg reduction (average) after 60 minutes; this was supported by microscopy showing significant biofilm disruption and an abundance of non-viable microcolony formations.

Conclusion

This study highlights the impact of irrigation solutions containing PHMB. It also demonstrated the effect of using different concentrations of PHMB in combination with surfactants as additives. The combination of 0.1% PHMB and poloxamer as a surfactant demonstrated effective benefits in eradicating established biofilm combined with a relatively high Therapeutic Index (TI), indicating low cytotoxicity and high bactericidal activity.

Identification of preoperative predictive markers of periprosthetic joint infection in presumed aseptic revisions of total hip arthroplasty: a retrospective observational study

INTRODUCTION

Periprosthetic joint infections (PJIs) occur at a rate of 1-2% in primary arthroplasties and 4% in revisions, posing a significant healthcare challenge. PJI diagnosis is hindered by absence of a universally accepted diagnostic standard. The primary outcome was to develop a predictive model to identify patients at risk of developing unforeseen PJI subsequent to presumed aseptic revision of total hip arthroplasty (THA). The secondary aim was to determine the reintervention-free survival rate among aseptic patients and those presenting unexpected positive cultures.

METHODS

This study included all ascertained septic and presumed aseptic patients without mechanical causes of THA failure and with sufficient clinical and laboratory data. Patients with incomplete anamnestic data, mechanical loosening related causes, rheumatologic conditions, or immunosuppression were excluded. Univariable and multivariable logistic regression analyses identified preoperative predictive markers for unexpected hip PJI.

RESULTS

283 inpatients from a high volume referral center were recruited from 2016 to 2019. The predictive preoperative parameters related with hip PJI were: presence of comorbidities (OR: 0.28; 95% CI 0.10-0.78), erythrocyte sedimentation rate (OR: 1.02; 95% CI 1.00-1.03), leukocyte count (OR: 1.18; 95% CI 1.02-1.36) and prothrombin time (OR: 1.42; 95% CI 1.02-1.98). Gender, age, body mass index (BMI) and previous surgery were not significantly related with unexpected PJI. Overall, the Kaplan-Meier analysis estimated a reoperation-free survival rate at 36 months of 96% (CI 95%) for the aseptic and 98% (CI 95%) for the unexpected group; however, the relation between the two survival curves was not significant (p = 0.086).

CONCLUSIONS

Erythrocyte sedimentation rate, leukocyte count, and increased prothrombin time were risk factors for PJI, whereas comorbidities were associated with a lower risk. Further research is needed to understand this association fully. Larger datasets are recommended to explore the complex interplay between risk factors and PJI development.

Brazilian red propolis reduces the adhesion of oral biofilm cells and the Toxoplasma gondii intracellular proliferation

Infectious diseases remain as a significant cause of thousands of deaths annually worldwide. Therefore, this study aimed to investigate the antimicrobial and antiparasitic activity of the crude hydroalcoholic extract and compounds isolated from Brazilian Red Propolis (BRP) against oral pathogens and Toxoplasma gondii, using in vitro, in vivo and in silico approaches. Antimicrobial and synergistic activities were determined using the broth dilution method and the checkerboard assay, respectively. Antibiofilm activity was evaluated by staining with 2 % crystal violet and counting microorganisms. In vivo infection was carried out in Caenorhabditis elegans AU37 larvae and in silico analysis was performed using molecular docking simulations. The effect on growth modulation of T. gondii was evaluated through a β-galactosidase colorimetric assay. Minimum Inhibitory Concentration values ranged from 3.12 to 400 µg/mL. Biofilm Minimum Inhibitory Concentration (MICB50) values ranged from 6.25 to 375 µg/mL, with a significant reduction in the number of viable cells. Furthermore, Guttiferone E and the crude extract reduced cell aggregation and caused damage to the biofilm cell wall. The highest concentrations of the crude extract and Guttiferone E increased the survival and reduced the risk of death of infected and treated larvae. Guttiferone E and Oblongifolin B inhibited the intracellular proliferation of T. gondii and demonstrated several targets of action against bacteria and T. gondii through in silico analysis. These data demonstrate that BRP has antimicrobial and antiparasitic activity against pathogens of clinical relevance, and can be used in the future as phytomedicines.

Feasibility of mNGS in joint replacement patients exhibiting elevated ESR and CRP levels without an underlying diagnosis

OBJECTIVE

The aim of this study is to investigate the viability of performing initial artificial joint replacement surgery in patients presenting with unexplained elevations in erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels.

METHODS

A cohort of 22 patients, comprising 11 cases each for knee and hip joint replacements, who underwent initial artificial joint replacement surgery between November 2020 and January 2022, was recruited. All patients exhibited elevated levels of ESR and CRP prior to surgery, the etiology of which remained undetermined. Intraoperatively, joint effusion and periarticular tissues were preserved for subsequent bacterial culture and metagenomic next-generation sequencing (mNGS). Postoperatively, a combination of intravenous and local antibiotics was administered for anti-infective management. In cases where bacterial culture and/or mNGS yielded positive results, patients were diagnosed with periprosthetic joint infections (PJI) and underwent one-stage revision; conversely, negative findings led to the discontinuation of intravenous and local antibiotics therapy.

RESULTS

Among the cohort of 22 patients, bacterial cultures yielded negative results, while mNGS identified bacterial infection in 14 patients (63.63%), viral infection in 1 patient (4.55%), and yielded negative results in 7 patients (31.82%). All surgical incisions achieved per primam. Subsequent follow-up assessments conducted for more than 1 year postoperatively revealed absence of PJI among the patients, all of whom exhibited satisfactory progress in their rehabilitation exercises. Notably, the Knee Society Score (KSS) for knee joint patients significantly improved from a preoperative mean of 48.7 ± 3.3 points to 84.3 ± 2.2 points postoperatively, whereas the Harris Hip Score for hip joint patients increased significantly from preoperative mean of 50.6 ± 3.6 points to 87.1 ± 1.6 points (P < 0.01).

CONCLUSION

In cases where patients present with unexplained elevations in ESR and CRP levels, primary artificial joint replacement can be undertaken following a one-stage revision approach for PJI.

The Antibacterial Potential of Brazilian Red Propolis against the Formation and Eradication of Biofilm of Helicobacter pylori

Helicobacter pylori is associated with gastrointestinal diseases, and its treatment is challenging due to antibiotic-resistant strains, necessitating alternative therapies. Brazilian red propolis (BRP), known for its diverse bioactive compounds with pharmaceutical properties, was investigated for its anti-H. pylori activity, focusing on biofilm formation inhibition and eradication. BRP was tested against H. pylori (ATCC 43526) using several assays: time-kill, nucleotide leakage, biofilm formation inhibition (determining the minimum inhibitory concentration of biofilm of 50%-MICB50, and cell viability), and biofilm eradication (determining the minimum eradication concentration of biofilm of 99.9%-MBEC). Standardization of H. pylori biofilm formation was also conducted. In the time-kill assay, BRP at 50 µg/mL eliminated all H. pylori cells after 24 h. The nucleotide leakage assay showed no significant differences between control groups and BRP-treated groups at 25 µg/mL and 50 µg/mL. H. pylori formed biofilms in vitro at 109 CFU/mL after 72 h. The MICB50 of BRP was 15.6 µg/mL, and at 500, 1000, and 2000 µg/mL, BRP eradicated all bacterial cells. The MBEC was 2000 µg/mL. These findings suggest that BRP has promising anti-H. pylori activity, effectively inhibiting and eradicating biofilms. Further studies are necessary to elucidate BRP's mechanisms of action against H. pylori.

Implant Mechanics, Biological Milieu, and Peri-Implantitis: A Narrative Review

Dental implants constitute an important treatment modality for rehabilitating edentulous and partially edentulous arches. With more implant systems in the market, understanding the mechanical aspects of implants is crucial in understanding this indispensable therapy. However, microflora-related factors i.e. biological factors are also crucial. Despite the tremendous success rate of dental implants, it is not averse to failure. Both mechanical and microbial aspects in seclusion or together predispose to implant failure. Newer technological advances have paved the way for advanced techniques to identify the not-so-common flora causing implant failure. This review focuses on detailed mechanical and biological aspects and the sealing agent used to seal the implant-abutment interface. It also focuses on advanced molecular techniques like metagenomics and transcriptomics. A thorough literature search was performed with selected articles from electronic databases. A combination of in-vivo and in-vitro studies were considered to provide comprehensive information on the subject. Both the biomechanical aspects like micro gap, and microleakage, as well as microbial movements play confluent roles in implant failure. The focus should be on the different aspects through which microflora can penetrate the inner parts of the implant. Also, newer culture-independent techniques of detecting previously undetected oral flora should be included in future studies.

Antibiofilm Strategies in Neonatal and Pediatric Infections

Biofilm-related infections pose significant challenges in neonatal and pediatric care, contributing to increased morbidity and mortality rates. These complex microbial communities, comprising bacteria and fungi, exhibit resilience against antibiotics and host immune responses. Bacterial species such as Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis commonly form biofilms on medical devices, exacerbating infection risks. Neonates and children, particularly those in intensive care units, are highly susceptible to biofilm-associated infections due to the prolonged use of invasive devices, such as central lines and endotracheal tubes. Enteral feeding tubes, crucial for neonatal nutritional support, also serve as potential sites for biofilm formation, contributing to recurrent microbial contamination. Moreover, Candida species, including Candida pelliculosa, present emerging challenges in neonatal care, with multi-drug resistant strains posing treatment complexities. Current antimicrobial therapies, while important in managing infections, often fall short in eradicating biofilms, necessitating alternative strategies. The aim of this review is to summarize current knowledge regarding antibiofilm strategies in neonates and in children. Novel approaches focusing on biofilm inhibition and dispersal show promise, including surface modifications, matrix-degrading enzymes, and quorum-sensing inhibitors. Prudent use of medical devices and exploration of innovative antibiofilm therapies are imperative in mitigating neonatal and pediatric biofilm infections.

A review of recent advances in the use of complex metal nanostructures for biomedical applications from diagnosis to treatment

Complex metal nanostructures represent an exceptional category of materials characterized by distinct morphologies and physicochemical properties. Nanostructures with shape anisotropies, such as nanorods, nanostars, nanocages, and nanoprisms, are particularly appealing due to their tunable surface plasmon resonances, controllable surface chemistries, and effective targeting capabilities. These complex nanostructures can absorb light in the near-infrared, enabling noteworthy applications in nanomedicine, molecular imaging, and biology. The engineering of targeting abilities through surface modifications involving ligands, antibodies, peptides, and other agents potentiates their effects. Recent years have witnessed the development of innovative structures with diverse compositions, expanding their applications in biomedicine. These applications encompass targeted imaging, surface-enhanced Raman spectroscopy, near-infrared II imaging, catalytic therapy, photothermal therapy, and cancer treatment. This review seeks to provide the nanomedicine community with a thorough and informative overview of the evolving landscape of complex metal nanoparticle research, with a specific emphasis on their roles in imaging, cancer therapy, infectious diseases, and biofilm treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Diagnostic Tools > Diagnostic Nanodevices.

Neutrophil to Lymphocyte Ratio and Periprosthetic Joint Infection: A Systematic Review and Meta-Analysis

BACKGROUND

The neutrophil-to-lymphocyte ratio (NLR) has shown promising results as a diagnostic tool for periprosthetic joint infection (PJI) after total joint arthroplasty. We conducted a systematic review and meta-analysis to determine the utility of NLR in the diagnosis of PJI.

METHODS

We searched PubMed, Scopus, and Web of Science from inception up to 2022 and evaluated the quality of the included literature.

RESULTS

Based on the 12 eligible studies, NLR levels were significantly higher in patients who had PJI compared to those who had aseptic loosening (standard mean difference (SMD) = 1.05, 95% Confidence Interval (CI) = 0.71 to 1.40, P < .001). In the subgroup analysis according to type of PJI, NLR levels were significantly higher in patients who had either acute (SMD = 1.04, 95% CI = 0.05 to 2.03, P < .001) or chronic PJI (SMD = 1.08, 95% CI = 0.55 to 1.61, P < .001), compared to those who had aseptic loosening. According to type of arthroplasty, NLR levels were significantly higher in patients who had either total knee arthroplasty (SMD = 1.81, 95% CI = 1.48 to 2.13, P < .001) or total hip arthroplasty (SMD = 1.76, 95% CI = 1.54 to 1.98, P < .001) compared to aseptic loosening. The pooled sensitivity of the 12 studies was 0.73 (95% CI, 0.65 to 0.79), and the pooled specificity was 0.75 (95% CI, 0.71 to 0.78). The pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of NLR were 2.94 (95% CI = 2.44 to 3.54), 0.35 (95% CI = 0.27 to 0.46), and 8.26 (95% CI = 5.42 to 12.58), respectively.

CONCLUSION

In summary, this meta-analysis indicates that NLR is a reliable marker in the diagnosis of PJI.

Host and microbial characteristics associated with recurrent prosthetic joint infections

Approximately 20% of patients after resection arthroplasty and antibiotic spacer placement for prosthetic joint infection develop repeat infections, requiring an additional antibiotic spacer before definitive reimplantation. The host and bacterial characteristics associated with the development of recurrent infection is poorly understood. A case-control study was conducted for 106 patients with intention to treat by two-stage revision arthroplasty for prosthetic joint infection at a single institution between 2009 and 2020. Infection was defined according to the 2018 Musculoskeletal Infection Society criteria. Thirty-nine cases ("recurrent-periprosthetic joint infection [PJI]") received at least two antibiotic spacers before clinical resolution of their infection, and 67 controls ("single-PJI") received a single antibiotic cement spacer before infection-free prosthesis reimplantation. Patient demographics, McPherson host grade, and culture results including antibiotic susceptibilities were compared. Fifty-two (78%) single-PJI and 32 (82%) recurrent-PJI patients had positive intraoperative cultures at the time of their initial spacer procedure. The odds of polymicrobial infections were 11-fold higher among recurrent-PJI patients, and the odds of significant systemic compromise (McPherson host-grade C) were more than double. Recurrent-PJI patients were significantly more likely to harbor Staphylococcus aureus. We found no differences between cases and controls in pathogen resistance to the six most tested antibiotics. Among recurrent-PJI patients, erythromycin-resistant infections were more prevalent at the final than initial spacer, despite no erythromycin exposure. Our findings suggest that McPherson host grade, polymicrobial infection, and S. aureus infection are key indicators of secondary or persistent joint infection following resection arthroplasty and antibiotic spacer placement, while bacterial resistance does not predict infection-related arthroplasty failure.

Dogs can detect an odor profile associated with Staphylococcus aureus biofilms in cultures and biological samples

Introduction

The study investigated the utilization of odor detection dogs to identify the odor profile of Staphylococcus aureus (S. aureus) biofilms in pure in vitro samples and in in vivo biosamples from animals and humans with S. aureus periprosthetic joint infection (PJI). Biofilms form when bacterial communities aggregate on orthopedic implants leading to recalcitrant infections that are difficult to treat. Identifying PJI biofilm infections is challenging, and traditional microbiological cultures may yield negative results even in the presence of clinical signs.

Methods

Dogs were trained on pure in vitro S. aureus biofilms and tested on lacrimal fluid samples from an in vivo animal model (rabbits) and human patients with confirmed S. aureus PJI.

Results

The results demonstrated that dogs achieved a high degree of sensitivity and specificity in detecting the odor profile associated with S. aureus biofilms in rabbit samples. Preliminary results suggest that dogs can recognize S. aureus volatile organic compounds (VOCs) in human lacrimal fluid samples.

Discussion

Training odor detection dogs on in vitro S. aureus, may provide an alternative to obtaining clinical samples for training and mitigates biosecurity hazards. The findings hold promise for culture-independent diagnostics, enabling early disease detection, and improved antimicrobial stewardship. In conclusion, this research demonstrates that dogs trained on in vitro S. aureus samples can identify the consistent VOC profile of PJI S. aureus biofilm infections. The study opens avenues for further investigations into a retained VOC profile of S. aureus biofilm infection. These advancements could revolutionize infectious disease diagnosis and treatment, leading to better patient outcomes and addressing the global challenge of antimicrobial resistance.

Exploiting phage-antibiotic synergies to disrupt Pseudomonas aeruginosa PAO1 biofilms in the context of orthopedic infections

IMPORTANCE

Biofilm-related infections are among the most difficult-to-treat infections in all fields of medicine due to their antibiotic tolerance and persistent character. In the field of orthopedics, these biofilms often lead to therapeutic failure of medical implantable devices and urgently need novel treatment strategies. This forthcoming article aims to explore the dynamic interplay between newly isolated bacteriophages and routinely used antibiotics and clearly indicates synergetic patterns when used as a dual treatment modality. Biofilms were drastically more reduced when both active agents were combined, thereby providing additional evidence that phage-antibiotic combinations lead to synergism and could potentially improve clinical outcome for affected patients.

Genome features of a novel hydrocarbonoclastic Chryseobacterium oranimense strain and its comparison to bacterial oil-degraders and to other C. oranimense strains

For the first time, we report the whole genome sequence of a hydrocarbonoclastic Chryseobacterium oranimense strain isolated from Trinidad and Tobago (COTT) and its genes involved in the biotransformation of hydrocarbons and xenobiotics through functional annotation. The assembly consisted of 11 contigs with 2,794 predicted protein-coding genes which included a diverse group of gene families involved in aliphatic and polycyclic hydrocarbon degradation. Comparative genomic analyses with 18 crude-oil degrading bacteria in addition to two C. oranimense strains not associated with oil were carried out. The data revealed important differences in terms of annotated genes involved in the hydrocarbon degradation process that may explain the molecular mechanisms of hydrocarbon and xenobiotic biotransformation. Notably, many gene families were expanded to explain COTT's competitive ability to manage habitat-specific stressors. Gene-based evidence of the metabolic potential of COTT supports the application of indigenous microbes for the remediation of polluted terrestrial environments and provides a genomic resource for improving our understanding of how to optimize these characteristics for more effective bioremediation.

Polyalthic Acid from Copaifera lucens Demonstrates Anticariogenic and Antiparasitic Properties for Safe Use

This study aimed at evaluating the potential of Copaifera lucens, specifically its oleoresin (CLO), extract (CECL), and the compound ent-polyalthic acid (PA), in combating caries and toxoplasmosis, while also assessing its toxicity. The study involved multiple assessments, including determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against cariogenic bacteria. CLO and PA exhibited MIC and MBC values ranging from 25 to 50 μg/mL, whereas CECL showed values equal to or exceeding 400 μg/mL. PA also displayed antibiofilm activity with minimum inhibitory concentration of biofilm (MICB50) values spanning from 62.5 to 1000 μg/mL. Moreover, PA effectively hindered the intracellular proliferation of Toxoplasma gondii at 64 μg/mL, even after 24 h without treatment. Toxicological evaluations included in vitro tests on V79 cells, where concentrations ranged from 78.1 to 1250 μg/mL of PA reduced colony formation. Additionally, using the Caenorhabditis elegans model, the lethal concentration (LC50) of PA was determined as 1000 μg/mL after 48 h of incubation. Notably, no significant differences in micronucleus induction and the NDI were observed in cultures treated with 10, 20, or 40 μg/mL of CLO. These findings underscore the safety profile of CLO and PA, highlighting their potential as alternative treatments for caries and toxoplasmosis.

Biofilm's Impact on Inflammatory Bowel Diseases

The colon has a large surface area covered with a thick mucus coating. Colon's biomass consists of about 1,012 colony-forming units per gram of feces and 500-1,000 distinct bacterial species. The term inflammatory bowel disease (IBD) indicates the collection of intestinal illnesses in which the digestive system (esophagus, large intestine, mouth, stomach, and small intestine) experiences persistent inflammation. IBD development is influenced by environmental (infections, stress, and nutrition) and genetic factors. The microbes present in gut microbiota help maintain intestinal homeostasis and support immune and epithelial cell growth, differentiation, as well as proliferation. It has been discovered that a variety of variables and microorganisms are crucial for the development of biofilms and mucosal colonization during IBD. An extracellular matrix formed by bacteria supports biofilm production in our digestive system and harms the host's immunological response. Irritable bowel syndrome (IBS) and IBD considerably affect human socioeconomic well-being and the standard of living. IBD is a serious public health issue, affecting millions of people across the globe. The gut microbiome may significantly influence IBS pathogenesis, even though few diagnostic and treatment options are available. As a result, current research focuses more on disrupting biofilm in IBD patients and stresses primarily on drugs that help improve the quality of life for human well-being. We evaluate studies on IBD and bacterial biofilm to add fresh insights into the existing state of knowledge of biofilm formation in IBD, incidence of IBD patients, molecular level of investigations, bacteria that are involved in the formation of biofilm, and present and down the line regimens and probiotics. Planning advanced ways to control and eradicate bacteria in biofilms should be the primary goal to add fresh insights into generating innovative diagnostic and alternative therapy options for IBD.

How effective is diluted povidone-iodine in preventing periprosthetic joint infection in total joint arthroplasty (TJA)? An updated systematic review and meta-analysis

PURPOSE

Periprosthetic joint infection (PJI) is a serious complication with total joint arthroplasty (TJA), that necessitates reoperation. Pre-closure irrigation with dilute povidone-iodine (PI) is among the preventive measures, but its efficiency is still controversial. As a result, the focus of this systematic review and meta-analysis is on the effect of dilute PI wound irrigation in the prevention of PJI following TJA.

METHODS

We systematically reviewed and analyzed articles that compared PI with other agents in terms of PJI rate after TJA, searching Medline, Scopus, Web of science, and Cochrane databases. A number of 13 papers including 63,950 patients in total, were finally considered in qualitative and quantitative assessments. We have also further assessed review articles.

RESULTS

In comparison with normal saline (NS), PI reduced post-operative infection rate (OR: 0.44; CI 95%: 0.34-0.56). However, there was no difference between PI and chlorhexidine (CHG) (OR: 1.61; CI 95%: 0.83-3.09)) or undetermined comparators (OR: 1.08; CI 95%: 0.67-1.76).

CONCLUSION

PI irrigation seems an efficient preventive measure for post-operative PJI and would seem to be the most feasible for TJA protocol.

Biofilms and Benign Colonic Diseases

The colon has a very large surface area that is covered by a dense mucus layer. The biomass in the colon includes 500-1000 bacterial species at concentrations of ~10¹² colony-forming units per gram of feces. The intestinal epithelial cells and the commensal bacteria in the colon have a symbiotic relationship that results in nutritional support for the epithelial cells by the bacteria and maintenance of the optimal commensal bacterial population by colonic host defenses. Bacteria can form biofilms in the colon, but the exact frequency is uncertain because routine methods to undertake colonoscopy (i.e., bowel preparation) may dislodge these biofilms. Bacteria in biofilms represent a complex community that includes living and dead bacteria and an extracellular matrix composed of polysaccharides, proteins, DNA, and exogenous debris in the colon. The formation of biofilms occurs in benign colonic diseases, such as inflammatory bowel disease and irritable bowel syndrome. The development of a biofilm might serve as a marker for ongoing colonic inflammation. Alternatively, the development of biofilms could contribute to the pathogenesis of these disorders by providing sanctuaries for pathogenic bacteria and reducing the commensal bacterial population. Therapeutic approaches to patients with benign colonic diseases could include the elimination of biofilms and restoration of normal commensal bacteria populations. However, these studies will be extremely difficult unless investigators can develop noninvasive methods for measuring and identifying biofilms. These methods that might include the measurement of quorum sensing molecules, measurement of bile acids, and identification of bacteria uniquely associated with biofilms in the colon.

Antibacterial Adhesion Strategy for Dental Titanium Implant Surfaces: From Mechanisms to Application

Dental implants are widely used to restore missing teeth because of their stability and comfort characteristics. Peri-implant infection may lead to implant failure and other profound consequences. It is believed that peri-implantitis is closely related to the formation of biofilms, which are difficult to remove once formed. Therefore, endowing titanium implants with anti-adhesion properties is an effective method to prevent peri-implant infection. Moreover, anti-adhesion strategies for titanium implant surfaces are critical steps for resisting bacterial adherence. This article reviews the process of bacterial adhesion, the material properties that may affect the process, and the anti-adhesion strategies that have been proven effective and promising in practice. This article intends to be a reference for further improvement of the antibacterial adhesion strategy in clinical application and for related research on titanium implant surfaces.

Diagnosis and Treatment of Culture-Negative Periprosthetic Joint Infection

Identification of the causative organism(s) in periprosthetic joint infection (PJI) is a challenging task. The shortcomings of traditional cultures have been emphasized in recent literature, culminating in a clinical entity known as "culture-negative PJI." Amidst the growing burden of biofilm infections that are inherently difficult to culture, the field of clinical microbiology has seen a paradigm shift from culture-based to molecular-based methods. These novel techniques hold much promise in the demystification of culture-negative PJI and revolutionization of the microbiology laboratory. This article outlines the clinical implications of culture-negative PJI, common causes of this diagnostic conundrum, established strategies to improve culture yield, and newer molecular techniques to detect infectious organisms.

Exploring the role of microbial biofilm for industrial effluents treatment

Biofilm formation on biotic or abiotic surfaces is caused by microbial cells of a single or heterogeneous species. Biofilm protects microbes from stressful environmental conditions, toxic action of chemicals, and antimicrobial substances. Quorum sensing (QS) is the generation of autoinducers (AIs) by bacteria in a biofilm to communicate with one other. QS is responsible for the growth of biofilm, synthesis of exopolysaccharides (EPS), and bioremediation of environmental pollutants. EPS is used for wastewater treatment due to its three-dimensional matrix which is composed of proteins, polysaccharides, humic-like substances, and nucleic acids. Autoinducers mediate significantly the degradation of environmental pollutants. Acyl-homoserine lactone (AHL) producing bacteria as well as quorum quenching enzyme or bacteria can effectively improve the performance of wastewater treatment. Biofilms-based reactors due to their economic and ecofriendly nature are used for the treatment of industrial wastewaters. Electrodes coated with electro-active biofilm (EAB) which are obtained from sewage sludge, activated sludge, or industrial and domestic effluents are getting popularity in bioremediation. Microbial fuel cells are involved in wastewater treatment and production of energy from wastewater. Synthetic biological systems such as genome editing by CRISPR-Cas can be used for the advanced bioremediation process through modification of metabolic pathways in quorum sensing within microbial communities. This narrative review discusses the impacts of QS regulatory approaches on biofilm formation, extracellular polymeric substance synthesis, and role of microbial community in bioremediation of pollutants from industrial effluents.

Enhanced Antibacterial and Osteogenic Properties of Graphene Oxide Loaded with Berberine on Biomedical Titanium

Internal implants are widely used in most orthopedic surgeries, of which titanium and its alloys are most widely used owing to the excellent corrosiveness resistance, low elastic modulus and good biocompatibility. However, implant failure still occurs for that titanium and its alloys themselves do not own antibacterial and osteogenic properties. In this work, we successfully fabricated berberine-loaded graphene oxide (GO) on the surface of biomedical titanium and systematically investigated its capabilities of antibacteria and osteogenesis. In vitro results showed that berberine had low antibacterial activity, but GO loaded with berberine on titanium (Ber&GO@Ti) exhibited superior antibacterial activity against Staphylococcus aureus (S. aureus) with the synergistic effect of GO and berberine. Meanwhile, Ber&GO@Ti performed satisfactory cytocompatibility and was capable of promoting osteogenic differentiation of MC3T3-E1 cells. In the vivo experiment, Ber&GO@Ti showed excellent antibacterial properties and inflammatory cells e.g., neutrophils had seldom been found. No visceral toxicity had been found. This multifunctional coating showed great potential in orthopedic implants.

Cryptococcus liquefaciens isolated from the hand of a healthcare professional in a neonatal intensive care unit

Fungal infections are responsible for high morbidity and mortality in neonatal patients, especially in premature newborns. Infections in neonates caused by Cryptococcus spp. are rare, but it has occurred in an immunocompromised population. This study aims to describe the isolation of Cryptococcus liquefaciens from the hands of a health professional in a neonatal intensive care unit, and to evaluate the production of biofilm and virulence factors and susceptibility to antifungals. Antifungal susceptibility tests were performed according to Clinical and Laboratory Standard Institute document M27-A3. Thermotolerance virulence factors and DNase, phospholipase, proteinase, and hemolytic activities were verified through phenotypic tests; biofilm was evaluated by determining the metabolic activity and biomass. The isolate did not produce any of the tested enzymes and was susceptible to all antifungals (amphotericin B, fluconazole, and micafungin). The growth at 37 °C was very weak; however, the isolate showed a strong biomass production and low metabolic activity. This is the first report of C. liquefaciens isolated from the hands of a health professional. The isolate did not express any of the studied virulence factors in vitro, except for the low growth at 37 °C in the first 48 h, and the strong production of biofilm biomass. Cryptococcus liquefaciens can remain in the environment for a long time and is a human pathogen because it tolerates temperature variations. This report draws attention to the circulation of rare species in critical locations, information that may help in a fast and correct diagnosis and, consequently, implementation of an appropriate treatment.

Effectiveness of diluted povidone-iodine lavage for preventing periprosthetic joint infection: an updated systematic review and meta-analysis

Background

Of the several methods used to prevent surgical site infection (SSI), diluted povidone-iodine (PI) lavage is used widely. However, the clinical utility of PI for preventing periprosthetic joint infection (PJI) remains controversial. The aim of this study was to perform a systematic review and meta-analysis of the utility of dilute PI lavage for preventing PJI in primary and revision surgery.

Methods

This study was conducted in accordance with the PRISMA checklist for systematic reviews and meta-analyses. A comprehensive literature search of PubMed, CINAHL, ClinicalTrials.gov, and Cochrane Library databases was performed. The results are summarized qualitatively and as a meta-analysis of pooled odds ratios with 95% confidence intervals (95% CIs). Heterogeneity of treatment effects among studies was classified as low, moderate, or high, corresponding to I² values of < 25%, 25–50%, and > 50%. A random effects model was applied in cases of high heterogeneity; otherwise, the fixed effects model was applied. Subgroup analyses were conducted to identify potential sources of heterogeneity.

Results

After the screening and eligibility assessment process, eight studies were finally extracted for analysis. Overall, the results showed that PI had no significant effect on PJI with ununified control group. However, subgroup analysis of studies with a saline control group revealed an odds ratio of 0.33 (95% CI, 0.16–0.71) for the PI group, suggesting a significant effect for preventing PJI.

Conclusion

The systematic review and meta-analysis of the current literature demonstrates that diluted PI lavage is significantly better than saline solution lavage for preventing PJI.

Level of evidence

Level I, Systematic review and meta-analysis.

Biomaterials and technologies in the management of periprosthetic infection after total hip arthroplasty: An updated review

Although total hip arthroplasty (THA) is considered one of the most efficacious procedures for managing various hip conditions, failures due to different mechanisms are still being reported. Periprosthetic joint infection (PJI) is one of the devastating causes of failure and revision of THA. PJI carries a burden on the patient, the surgeon, and the health-care system. The diagnosis and management of PJIs carry many morbidities and increased treatment costs. The development of PJI is multifactorial, including issues related to the patient’s general condition, the surgeon’s efficiency, surgical technique, and the implants used. Recent advances in the area of diagnosis and predicting PJI as well as introducing new technologies and biomaterials update for the prevention and treatment of PJI. Local implant coatings, advancement in the bearing surfaces technologies, and new technologies such as immunotherapy and bacteriophage therapy were introduced and suggested as contemporary PJI eradication solutions. In this review, we aimed at discussing some of the newly introduced materials and technologies for the sake of PJI control.

Is Negative Pressure Wound Therapy with Instillation Suitable for the Treatment of Acute Periprosthetic Hip Joint Infection?

Background: Periprosthetic joint infection (PJI) can be devastating for the patient and demanding for the surgeon. In acute PJI, attempts are made to retain the prosthesis by debridement of the infected tissue, targeted antibiotic therapy and an exchange of modular components with implant retention (DAIR). There has been sparse research with adjunctive negative pressure wound treatment with wound irrigation (NPWTI) on the treatment outcome. Questions/purposes: The goal was to assess the efficacy of our protocol of DAIR with adjunctive NPWTI in acute PJI and to reduce the need for later additional DAIR and Irrigation and Debridement (I and D). Patients and Methods: Our cohort of 30 patients (31 hips) with acute PJI was divided into two groups based on symptom presentation up to 6 weeks or >6 weeks from prior (index) surgery (acute early or acute late groups, respectively). All received DAIR with an exchange of modular components and NPWTI with polyhexanide instillation, with the goal of bacterial elimination and biofilm elimination. Postoperatively, the patients were followed up clinically and radiographically for a mean of 4.3 years. Results: Of the 31 PJI hips, 19 were early acute and 12 were late acute. In total, 21 hips had no evidence of residual infection, 10 required further surgical revision: 1 due to dislocation and 9 due to infection. Of these nine, seven had a removal of all the components and two were treated with irrigation and debridement (I and D), with the demise of one patient from pneumonia shortly after the procedure. The Kaplan–Meier 60-month revision free implant survival from infection was 73.2% (CI: 58.9–91.0%) and at the final follow up, the mean Harris Hip Score (HHS) was 81.1 ± 11.8 and the mean WOMAC score was 33.3 ± 20.1. Conclusions: Our results are in line with those reported in prior studies. However, the utility of our protocol is inconclusive and needs further evaluation based on our small cohort and the lack of a control group. Level of Evidence: IV.

Engineering a Bifunctional ComQXPA-PsrfA Quorum-Sensing Circuit for Dynamic Control of Gene Expression in Corynebacterium glutamicum

Corynebacterium glutamicum is an important industrial workhorse for the production of amino acids and other chemicals. However, the engineering of C. glutamicum is inflexible due to the lack of dynamic regulation tools. In this study, a quorum sensing (QS) circuit and its modulated hfq-sRNA cassette were constructed, and the dynamic control of gene expression by these bifunctional circuits was researched. First, the ComQXPA-P_srfA QS system of Bacillus subtilis was harnessed and modified to create an upregulating QS circuit, in which the transcription of genes controlled by the P_srfA promoter may be promoted at high cell density. This QS circuit successfully activated the expression of green fluorescent protein (GFP) to 6.35-fold in a cell density-dependent manner in C. glutamicum. Next, the hfq-sRNA-mediated downregulating circuit under the control of the ComQXPA-P_srfA QS system was established, and the expression of GFP was autonomously repressed by 96.1%. Next, to fine-tune these two QS circuits, a library of synthetic P_srfA based promoters was constructed, and a series of mutant P_srfAM promoters with 0.4-1.5-fold strength of native P_srfA were selected. Subsequently, the ComQXPA-P_srfAM QS circuit was utilized to upregulate the expression of red fluorescent protein, and the same QS-based hfq-sRNA system was utilized to downregulate the expression of GFP simultaneously. Last, this bifunctional ComQXPA-P_srfAM QS circuit was verified again by fine-tuning the expression of α-amylase. Therefore, the engineered ComQXPA-P_srfAM QS cassette can be applied as a novel bifunctional QS circuit to flexibly control gene expression in C. glutamicum.

The Staphylococcus aureus toxin-antitoxin system YefM-YoeB is associated with antibiotic tolerance and extracellular dependent biofilm formation

The high antibiotic tolerance of Staphylococcus aureus biofilms is associated with challenges for treating periprosthetic joint infection. The toxin–antitoxin system, YefM–YoeB, is thought to be a regulator for antibiotic tolerance, but its physiological role is unknown. The objective of this study was to determine the biofilm and antibiotic susceptibility phenotypes associated with S. aureus yoeB homologs. We hypothesized the toxin–antitoxin yoeB homologs contribute to biofilm formation and antibiotic susceptibility. Disruption of yoeB1 and yoeB2 resulted in decreased biofilm formation in comparison to Newman and JE2 wild-type (WT) S. aureus strains. In comparison to yoeB mutants, both Newman and JE2 WT strains had higher polysaccharide intercellular adhesin (PIA) production. Treatment with sodium metaperiodate increased biofilm formation in Newman WT, indicating biofilm formation may be increased under conditions of oxidative stress. DNase I treatment decreased biofilm formation in Newman WT but not in the absence of yoeB1 or yoeB2. Additionally, WT strains had a higher extracellular DNA (eDNA) content in comparison to yoeB mutants but no differences in biofilm protein content. Moreover, loss of yoeB1 and yoeB2 decreased biofilm survival in both Newman and JE2 strains. Finally, in a neutropenic mouse abscess model, deletion of yoeB1 and yoeB2 resulted in reduced bacterial burden. In conclusion, our data suggest that yoeB1 and yoeB2 are associated with S. aureus planktonic growth, extracellular dependent biofilm formation, antibiotic tolerance, and virulence.

Tolerant Small-colony Variants Form Prior to Resistance Within a Staphylococcus aureus Biofilm Based on Antibiotic Selective Pressure

BACKGROUND

The treatment of periprosthetic joint infection (PJI) is focused on the surgical or chemical removal of biofilm. Antibiotics in isolation are typically ineffective against PJI. Bacteria survive after antibiotic administration because of antibiotic tolerance, resistance, and persistence that arise in the resident bacteria of a biofilm. Small-colony variants are typically slow-growing bacterial subpopulations that arise after antibiotic exposure and are associated with persistent and chronic infections such as PJI. The role of biofilm-mediated antibiotic tolerance in the emergence of antibiotic resistance remains poorly defined experimentally.

QUESTIONS/PURPOSES

We asked: (1) Does prior antibiotic exposure affect how Staphylococcus aureus survives within a developing biofilm when exposed to an antibiotic that penetrates biofilm, like rifampicin? (2) Does exposure to an antibiotic with poor biofilm penetration, such as vancomycin, affect how S. aureus survives within a developing biofilm? (3) Do small-colony variants emerge from antibiotic-tolerant or -resistant bacteria in a S. aureus biofilm?

METHODS

We used a porous membrane as an in vitro implant model to grow luminescent S. aureus biofilms and simultaneously track microcolony expansion. We evaluated the impact of tolerance on the development of resistance by comparing rifampicin (an antibiotic that penetrates S. aureus biofilm) with vancomycin (an antibiotic that penetrates biofilm poorly). We performed viability counting after membrane dissociation to discriminate among tolerant, resistant, and persistent bacteria. Biofilm quantification and small-colony morphologies were confirmed using scanning electron microscopy. Because of experimental variability induced by the starting bacterial inoculum, relative changes were compared since absolute values may not have been statistically comparable.

RESULTS

Antibiotic-naïve S. aureus placed under the selective pressure of rifampicin initially survived within an emerging biofilm by using tolerance given that biofilm resident cell viability revealed 1.0 x 108 CFU, of which 7.5 x 106 CFU were attributed to the emergence of resistance and 9.3 x 107 CFU of which were attributed to the development of tolerance. Previous exposure of S. aureus to rifampicin obviated tolerance-mediate survival when rifampicin resistance was present, since the number of viable biofilm resident cells (9.5 x 109 CFU) nearly equaled the number of rifampicin-resistant bacteria (1.1 x 1010 CFU). Bacteria exposed to an antibiotic with poor biofilm penetration, like vancomycin, survive within an emerging biofilm by using tolerance as well because the biofilm resident cell viability for vancomycin-naïve (1.6 x 1010 CFU) and vancomycin-resistant (1.0 x 1010 CFU) S. aureus could not be accounted for by emergence of resistance. Adding rifampicin to vancomycin resulted in a nearly 500-fold reduction in vancomycin-tolerant bacteria from 1.5 x 1010 CFU to 3.3 x 107 CFU. Small-colony variant S. aureus emerged within the tolerant bacterial population within 24 hours of biofilm-penetrating antibiotic administration. Scanning electron microscopy before membrane dissociation confirmed the presence of small, uniform cells with biofilm-related microstructures when unexposed to rifampicin as well as large, misshapen, lysed cells with a small-colony variant morphology [29, 41, 42, 63] and a lack of biofilm-related microstructures when exposed to rifampicin. This visually confirmed the rapid emergence of small-colony variants within the sessile niche of a developing biofilm when exposed to an antibiotic that exerted selective pressure.

CONCLUSION

Tolerance explains why surgical and nonsurgical modalities that rely on antibiotics to "treat" residual microscopic biofilm may fail over time. The differential emergence of resistance based on biofilm penetration may explain why some suppressive antibiotic therapies that do not penetrate biofilm well may rely on bacterial control while limiting the emergence of resistance. However, this strategy fails to address the tolerant bacterial niche that harbors persistent bacteria with a small-colony variant morphology.

CLINICAL RELEVANCE

Our work establishes biofilm-mediated antibiotic tolerance as a neglected feature of bacterial communities that prevents the effective treatment of PJI.

Nanotechnology as an Anti-Infection Strategy in Periprosthetic Joint Infections (PJI)

Background: Periprosthetic joint infection (PJI) represents a devastating consequence of total joint arthroplasty (TJA) because of its high morbidity and its high impact on patient quality of life. The lack of standardized preventive and treatment strategies is a major challenge for arthroplasty surgeons. The purpose of this article was to explore the potential and future uses of nanotechnology as a tool for the prevention and treatment of PJI. Methods: Multiple review articles from the PubMed, Scopus and Google Scholar databases were reviewed in order to establish the current efficacy of nanotechnology in PJI preventive or therapeutic scenarios. Results: As a prevention tool, anti-biofilm implants equipped with nanoparticles (silver, silk fibroin, poly nanofibers, nanophase selenium) have shown promising antibacterial functionality. As a therapeutic tool, drug-loaded nanomolecules have been created and a wide variety of carrier materials (chitosan, titanium, calcium phosphate) have shown precise drug targeting and efficient control of drug release. Other nanotechnology-based antibiotic carriers (lipid nanoparticles, silica, clay nanotubes), when added to common bone cements, enhanced prolonged drug delivery, making this technology promising for the creation of antibiotic-added cement joint spacers. Conclusion: Although still in its infancy, nanotechnology has the potential to revolutionize prevention and treatment protocols of PJI. Nevertheless, extensive basic science and clinical research will be needed to investigate the potential toxicities of nanoparticles.

Anti-Periprosthetic Infection Strategies: From Implant Surface Topographical Engineering to Smart Drug-Releasing Coatings

Despite advanced implant sterilization and aseptic surgical techniques, periprosthetic bacterial infection remains a major challenge for orthopedic and dental implants. Bacterial colonization/biofilm formation around implants and their invasion into the dense skeletal tissue matrices are difficult to treat and could lead to implant failure and osteomyelitis. These complications require major revision surgeries and extended antibiotic therapies that are associated with high treatment cost, morbidity, and even mortality. Effective preventative measures mitigating risks for implant-related infections are thus in dire need. This review focuses on recent developments of anti-periprosthetic infection strategies aimed at either reducing bacterial adhesion, colonization, and biofilm formation or killing bacteria directly in contact with and/or in the vicinity of implants. These goals are accomplished through antifouling, quorum-sensing interfering, or bactericidal implant surface topographical engineering or surface coatings through chemical modifications. Surface topographical engineering of lotus leaf mimicking super-hydrophobic antifouling features and cicada wing-mimicking, bacterium-piercing nanopillars are both presented. Conventional physical coating/passive release of bactericidal agents is contrasted with their covalent tethering to implant surfaces through either stable linkages or linkages labile to bacterial enzyme cleavage or environmental perturbations. Pros and cons of these emerging anti-periprosthetic infection approaches are discussed in terms of their safety, efficacy, and translational potentials.

Biological and Physiochemical Methods of Biofilm Adhesion Resistance Control of Medical-Context Surface

The formation of biofilms on medical-context surfaces gives the EPS embedded bacterial community protection and additional advantages that planktonic cells would not have such as increased antibiotic resistance and horizontal gene transfer. Bacterial cells tend to attach to a conditioning layer after overcoming possible electrical barriers and go through two phases of attachments: reversible and irreversible. In the first, bacterial attachment to the surface is reversible and occurs quickly whilst the latter is permanent and takes place over a longer period of time. Upon reaching a certain density in the bacterial community, quorum sensing causes phenotypical changes leading to a loss in motility and the production of EPS. This position paper seeks to address the problem of bacterial adhesion and biofilm formation for the medical surfaces by comparing inhabiting physicochemical interactions and biological mechanisms. Several physiochemical methodologies (e.g. ultrasonication, alternating magnetic field and chemical surface coating) and utilizing biological mechanisms (e.g. quorum quenching and EPS degrading enzymes) were suggested. The possible strategical applications of each category were suggested and evaluated to a balanced position to possibly eliminate the adhesion and formation of biofilms on medical-context surfaces.

Diagnosis of biofilm infections: current methods used, challenges and perspectives for the future

The diagnosis of biofilms continues to be a challenge, and there is no standardized protocol for such a diagnosis in clinical practice. In addition, some proposed methodologies are expensive to require significant amounts of time and a high number of trained staff, making them impracticable for clinical practice. In recent years, mass spectrophotometry/matrix-assisted laser desorption ionization time of flight (MALDI-TOF) has been applied it in biofilm studies. However, due to several problems and limitations of the technique, MALDI-TOF is far from being the gold standard for identifying biofilm formation. The omics analysis may prove to be a promising strategy for the diagnosis of biofilms in clinical laboratories since it allows the identification of pathogens in less time than needed for conventional techniques and in a more specific manner. However, omic tools are expensive and require qualified technical expertise, and an analysis of the data obtained needs to be careful not to neglect subpopulations in the biofilm. More studies must therefore be developed for creating a protocol that guarantees rapid biofilm identification, ensuring greater chances of success in infection control. This review discusses the current methods of microbial biofilm detection and future perspectives for its diagnosis in clinical practice.

The Rationale for Using Bacteriophage to Treat and Prevent Periprosthetic Joint Infections

Prosthetic joint infection (PJI) is a devastating complication after a joint replacement. PJI and its treatment have a high monetary cost, morbidity, and mortality. The lack of success treating PJI with conventional antibiotics alone is related to the presence of bacterial biofilm on medical implants. Consequently, surgical removal of the implant and prolonged intravenous antibiotics to eradicate the infection are necessary prior to re-implanting a new prosthetic joint. Growing clinical data shows that bacterial predators, called bacteriophages (phages), could be an alternative treatment strategy or prophylactic approach for PJI. Phages could further be exploited to degrade biofilms, making bacteria more susceptible to antibiotics and enabling potential combinatorial therapies. Emerging research suggests that phages may also directly interact with the innate immune response. Phage therapy may play an important, and currently understudied, role in the clearance of PJI, and has the potential to treat thousands of patients who would either have to undergo revision surgery to attempt to clear an infections, take antibiotics for a prolonged period to try and suppress the re-emerging infection, or potentially risk losing a limb.

Prosthetic joint infection. A relevant public health issue

Prosthetic joint infection (PJI) is a common complication of the knee and hip arthroplasty and represents a huge challenge for physicians. PJI raises serious social, economic and clinical concerns in the public health that need a comprehensive approach to better focus on proven strategies for disease prevention and treatment. History and clinical signs on joint site are useful means for suspecting PJI that need to be confirmed through major and minor diagnostic criteria. The pathogen isolation and the resulting antibiogram are crucial to guide the correct antibiotic strategy and together with surgical treatment (prosthesis revision and spacer implantation) represent the cornerstones to eradicate the infection before attempting a new arthroplasty. External fixator with removal of the spacer may be an option before performing a new arthroplasty when the infection does not heal. Arthrodesis may also be considered if the arthroplasty is contraindicated. Limb amputation is the last chance when pathogen eradication failed and might lead to life-threatening situations.

Debridement, antibiotic pearls, and retention of the implant in the treatment of infected total hip arthroplasty

In this article the authors describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure to improve the possibilities of retaining a total hip arthroplasty (THA) undergoing acute periprosthetic joint infection (PJI). This technique, debridement antibiotic pearls and retention of the implant (DAPRI), aims to remove the intra-articular biofilm allowing a higher and prolonged local antibiotic concentration by using calcium sulphate antibiotic-added beads. The combination of 3 different surgical techniques (tumour-like synovectomy, Argon Beam application and chlorhexidine gluconate brushing) might enhance the disruption and removal of the bacterial biofilm which is the main responsible of antibiotics and antibodies resistance. The timing of the diagnosis (6 weeks from the original surgery or 1 week from clinical symptoms appearance in the case of an hematogenous infection) and the preoperative isolation of the germ are fundamental in order to obtain a satisfactory outcome. A 12-week course of postoperative antibiotic therapy (6 weeks I.V. and 6 weeks oral) complete the postoperative protocol used by the authors.The DAPRI technique might represent a safe and more conservative treatment for acute and early hematogenous PJI.

Microbial biofilm ecology, in silico study of quorum sensing receptor-ligand interactions and biofilm mediated bioremediation

Biofilms are structured microbial communities of single or multiple populations in which microbial cells adhere to a surface and get embedded in extracellular polymeric substances (EPS). This review attempts to explain biofilm architecture, development phases, and forces that drive bacteria to promote biofilm mode of growth. Bacterial chemical communication, also known as Quorum sensing (QS), which involves the production, detection, and response to small molecules called autoinducers, is highlighted. The review also provides a brief outline of interspecies and intraspecies cell-cell communication. Additionally, we have performed docking studies using Discovery Studio 4.0, which has enabled our understanding of the prominent interactions between autoinducers and their receptors in different bacterial species while also scoring their interaction energies. Receptors, such as LuxN (Phosphoreceiver domain and RecA domain), LuxP, and LuxR, interacted with their ligands (AI-1, AI-2, and AHL) with a CDocker interaction energy of - 31.6083 kcal/mole; - 34.5821 kcal/mole, - 48.2226 kcal/mole and - 41.5885 kcal/mole, respectively. Since biofilms are ideal for the remediation of contaminants due to their high microbial biomass and their potential to immobilize pollutants, this article also provides an overview of biofilm-mediated bioremediation.

Mesoporous Silica Nanoparticles for the Treatment of Complex Bone Diseases: Bone Cancer, Bone Infection and Osteoporosis

Bone diseases, such as bone cancer, bone infection and osteoporosis, constitute a major issue for modern societies as a consequence of their progressive ageing. Even though these pathologies can be currently treated in the clinic, some of those treatments present drawbacks that may lead to severe complications. For instance, chemotherapy lacks great tumor tissue selectivity, affecting healthy and diseased tissues. In addition, the inappropriate use of antimicrobials is leading to the appearance of drug-resistant bacteria and persistent biofilms, rendering current antibiotics useless. Furthermore, current antiosteoporotic treatments present many side effects as a consequence of their poor bioavailability and the need to use higher doses. In view of the existing evidence, the encapsulation and selective delivery to the diseased tissues of the different therapeutic compounds seem highly convenient. In this sense, silica-based mesoporous nanoparticles offer great loading capacity within their pores, the possibility of modifying the surface to target the particles to the malignant areas and great biocompatibility. This manuscript is intended to be a comprehensive review of the available literature on complex bone diseases treated with silica-based mesoporous nanoparticles-the further development of which and eventual translation into the clinic could bring significant benefits for our future society.

Partially Melted Ti6Al4V Particles Increase Bacterial Adhesion and Inhibit Osteogenic Activity on 3D-printed Implants: An In Vitro Study

BACKGROUND

A porous Ti6Al4V implant that is manufactured using selective laser melting (SLM) has broad potential applications in the field of orthopaedic implants. The pore structure of the SLM porous Ti6Al4V implant allows for cell migration and osteogenic differentiation, which is favorable for bone ingrowth and osseointegration. However, it is unclear whether the pore structure and partially melted Ti6Al4V particles on a SLM porous Ti6Al4V implant will increase bacterial adhesion and, perhaps, the risk of implant-related infection.

QUESTIONS/PURPOSES

(1) Is there more bacterial adhesion and colonization on SLM porous Ti6Al4V implants than on polished orthopaedic implants? (2) Do partially melted Ti6Al4V particles on SLM porous Ti6Al4V implants reduce human bone mesenchymal stem cells (hBMSCs) adhesion, viability, and activity?

METHODS

To determine bacterial adhesion and biofilm formation, we incubated five different Ti6Al4V discs (polished, grit-blasted, plasma-sprayed, particle SLM porous, and nonparticle SLM porous discs) with methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Bacterial coverage on the surface of the five different Ti6Al4V discs were evaluated based on scanning electron microscopy (SEM) images quantitatively. In addition, a spread-plate method was used to quantitatively evaluate the bacterial adhesion on those implants. The biofilm formation was stained with crystal violet and semi-quantitatively determined with a microplate reader. The morphology and adhesion of hBMSCs on the five Ti6Al4V discs were observed with SEM. The cell viability was quantitatively evaluated with a Cell Counting Kit-8 assay. In addition, the osteogenic activity was determined in vitro with a quantitatively alkaline phosphatase activity assay and alizarin-red staining. For semiquantitative analysis, the alizarin-red stained mineralized nodules were dissolved and determined with a microplate reader.

RESULTS

The polished discs had the lowest MRSA adhesion (8.3% ± 2.6%) compared with grit-blasted (19.1% ± 3.9%; p = 0.006), plasma-sprayed (38.5% ± 5.3%; p < 0.001), particle (23.1% ± 2.8%; p < 0.001), and nonparticle discs (15.7% ± 2.5%; p = 0.003). Additionally, when comparing the two SLM discs, we found that particle discs had higher bacterial coverage than nonparticle discs (23.1% ± 2.8% versus 15.7% ± 2.5%; p = 0.020). An E. coli analysis showed similar results, with the higher adhesion to particle SLM discs than to nonparticle discs (20.7% ± 4.2% versus 14.4% ± 3.6%; p = 0.011). In addition, on particle SLM porous discs, bacterial colonies were localized around the partially melted Ti6Al4V particles, based on SEM images. After a 7-day incubation period, the cell viability in the particle group (optical density value 0.72 ± 0.05) was lower than that in the nonparticle groups (optical density value: 0.87 ± 0.08; p = 0.003). Alkaline phosphatase activity, as a marker of osteogenic differentiation, was lower in the particle group than in the nonparticle group (1.32 ± 0.12 U/mL versus 1.58 ± 0.09 U/mL; p = 0.012).

CONCLUSION

Higher bacterial adhesion was observed on SLM porous discs than on polished discs. The partially melted Ti6Al4V particles on SLM porous discs not only enhanced bacterial adhesion but also inhibited the osteogenic activity of hBMSCs. Postprocessing treatment is necessary to remove partially melted Ti6Al4V particles on an SLM implant before further use. Additional studies are needed to determine whether an SLM porous Ti6Al4V implant increases the risk of implant-related infection in vivo.

CLINICAL RELEVANCE

As implants with porous Ti6Al4V made using SLM are being designed, our preliminary findings suggest that postprocessing treatment is needed to remove partially melted Ti6Al4V particles before further use. In addition, the depth of the porous structure of the SLM implant should not exceed the maximum depth of bone ingrowth because the host immune defense cannot prevent bacterial adhesion without integration.

Hijacking the Bacterial Circuitry of Biofilm Processes via Chemical "Hot-Wiring": An Under-explored Avenue for Therapeutic Development

Biofilm-associated infections are linked to chronic and recurring illnesses. These infections are often not susceptible to current antibiotic treatments because of the protective exocellular matrix and subpopulations of dormant or "persister" cells. Targeting bacterial circuitry involved in biofilm formation, including two-component systems, quorum sensing, polysaccharide structural integrity, and cyclic nucleotide signaling pathways, has the potential to expand the existing arsenal of therapeutics, thus catalyzing a second golden age of antibiotic development.

Mesoporous Silica Materials as Drug Delivery: "The Nightmare" of Bacterial Infection

Mesoporous silica materials (MSM) have a great surface area and a high pore volume, meaning that they consequently have a large loading capacity, and have been demonstrated to be unique candidates for the treatment of different pathologies, including bacterial infection. In this text, we review the multiple ways of action in which MSM can be used to fight bacterial infection, including early detection, drug release, targeting bacteria or biofilm, antifouling surfaces, and adjuvant capacity. This review focus mainly on those that act as a drug delivery system, and therefore that have an essential characteristic, which is their great loading capacity. Since MSM have advantages in all stages of combatting bacterial infection; its prevention, detection and finally in its treatment, we can venture to talk about them as the "nightmare of bacteria".