Assessing Cytotoxicity, Proteolytic Stability, and Selectivity of Antimicrobial Peptides: Implications for Orthopedic Applications.

In orthopedics, the use of anti-infective biomaterials is considered the most promising strategy to contrast the bacterial contamination of implant surfaces and reduce the infection rate. KSL, KSL-W, and Dadapin-1 are three antimicrobial peptides (AMPs) that possess significant antibacterial properties, making them promising candidates for producing anti-infective biomaterials not based on antibiotics. To fully assess their true potential, this study explores in detail their cytocompatibility on human osteoblast-like MG63 cells, murine fibroblastoid L929 cells, and hMSCs.

The Opportunistic Pathogen : Virulence and Antibiotic Resistance, Clinical Features, Association with Orthopedic Implants and Other Medical Devices, and a Glance at Industrial Applications.

In recent decades, the risk of developing opportunistic infections has increased in parallel with the ever-increasing number of people suffering from chronic immunosuppressive diseases or undergoing prosthetic surgery. is a Gram-positive and coagulase-negative bacterium. Usually found as a component of the healthy human and animal microbiota of the skin and mucosae, it can take on the role of an opportunistic pathogen capable of causing a variety of infections, ranging from mild to life-threatening, not only in immunocompromised patients but even, although rarely, in healthy people.

Emerging Issues and Initial Insights into Bacterial Biofilms: From Orthopedic Infection to Metabolomics.

Bacterial biofilms, enigmatic communities of microorganisms enclosed in an extracellular matrix, still represent an open challenge in many clinical contexts, including orthopedics, where biofilm-associated bone and joint infections remain the main cause of implant failure. This study explores the scenario of biofilm infections, with a focus on those related to orthopedic implants, highlighting recently emerged substantial aspects of the pathogenesis and their potential repercussions on the clinic, as well as the progress and gaps that still exist in the diagnostics and management of these infections. The classic mechanisms through which biofilms form and the more recently proposed new ones are depicted.

Interactions of Neutrophils with the Polymeric Molecular Components of the Biofilm Matrix in the Context of Implant-Associated Bone and Joint Infections.

In the presence of orthopedic implants, opportunistic pathogens can easily colonize the biomaterial surfaces, forming protective biofilms. Life in biofilm is a central pathogenetic mechanism enabling bacteria to elude the host immune response and survive conventional medical treatments. The formation of mature biofilms is universally recognized as the main cause of septic prosthetic failures.

Biofilms in Periprosthetic Orthopedic Infections Seen through the Eyes of Neutrophils: How Can We Help Neutrophils?

Despite advancements in our knowledge of neutrophil responses to planktonic bacteria during acute inflammation, much remains to be elucidated on how neutrophils deal with bacterial biofilms in implant infections. Further complexity transpires from the emerging findings on the role that biomaterials play in conditioning bacterial adhesion, the variety of biofilm matrices, and the insidious measures that biofilm bacteria devise against neutrophils. Thus, grasping the entirety of neutrophil-biofilm interactions occurring in periprosthetic tissues is a difficult goal.

Searching for Virulence Factors among Isolates from Orthopedic Infections: Correlation of , and Genes with Hemolytic Activity and Synergistic Hemolytic Activity.

is an emerging high-virulent pathogen. Here, the presence and expression of virulence genes (, , , , , and , and genes of the putative and ) and the ability to induce synergistic hemolytic activity and hemolysis after 24, 48 and 72 h were investigated in a collection of twenty-two clinical isolates. The collection of isolates, mainly from implant orthopedic infections, had previously been grouped by ribotyping/dendrogram analysis and studied for biofilm matrices, biomasses and antibiotic resistances.

Antibacterial Activity on Orthopedic Clinical Isolates and Cytotoxicity of the Antimicrobial Peptide Dadapin-1.

In orthopedic surgery, biomaterial-associated infections represent a complication of serious concern. Most promising strategies to prevent these infections currently rely on the use of anti-infective biomaterials. Desirably, in anti-infective biomaterials, the antibacterial properties should be achieved by doping, grafting, or coating the material surfaces with molecules that are alternative to conventional antibiotics and exhibit a potent and highly specific activity against bacteria, without altering the biocompatibility.

Comparison of Automated Ribotyping, Typing, and MLST in 108 Clinical Isolates of from Orthopedic Infections.

108 isolates of , belonging to six large ribogroups according to the automated Ribo-Printer system, were studied with two highly used molecular methods for epidemiological studies, namely multi-locus sequence typing (MLST) and typing, followed by BURP and eBURST v3 analysis for clustering types and sequence (ST) types. The aim was to evaluate whether automated ribotyping could be considered a useful screening tool for identifying genetic lineages with respect to typing and MLST. Clarifying the relationship of riboprinting with these typing methods and establishing whether ribogroups fit single clonal complexes were two main objectives.

Synthesis, Crystal Structure, and Antibacterial Properties of Silver-Functionalized Low-Dimensional Layered Zirconium Phosphonates.

New insoluble layered zirconium phosphate carboxyaminophosphonates (ZPs), with the general formula Zr(PO)H[(OPCH)N(CH)COO]·HO ( = 3, 4, and 5), have been prepared and characterized. The crystal structure for = 3 and 4 samples was determined from X-ray powder diffraction data. The structure for = 3 was monoclinic in space group 2/ with the following unit cell parameters: = 34.

Exploring the anticancer effects of standardized extracts of poplar-type propolis: In vitro cytotoxicity toward cancer and normal cell lines.

Propolis was shown to exert antimicrobial, antioxidant, anti-inflammatory, and anticancer activities. Its composition is influenced by seasonal, climatic and phytogeographic conditions. Further variability derives from the extraction methods.

Various biofilm matrices of the emerging pathogen : exopolysaccharides, proteins, eDNA and their correlation with biofilm mass.

is an emerging high-virulent pathogen causative of hospital-acquired infections. Biofilm formation is a complex pathogenic process that leads to well-established bacterial communities. There is a paucity of data on the composition of the biofilm matrix among strains.

Zirconium Carboxyaminophosphonate Nanosheets as Support for Ag Nanoparticles.

A layered insoluble inorganic-organic solid, namely zirconium phosphate glycine-N,N-bismethylphosphonate, was used to prepare dispersions of nanosheets to support active metals such as metallic silver nanoparticles and zinc ions. Zr phosphate-phosphonate microcrystals were first exfoliated with methylamine to produce a stable colloidal dispersion and then the methylamine was removed by treatment with hydrochloric acid. The obtained colloidal dispersion of Zr phosphate-phosphonate nanosheets was used to immobilize silver or zinc cations, via ion exchange, with the acidic protons of the sheets.

Antibacterial Properties of a Novel Zirconium Phosphate-Glycinediphosphonate Loaded with Either Zinc or Silver.

A novel compound consisting of a zirconium phosphate-glycinediphosphonate (ZPGly) has recently been introduced. This 2D-structured material forming nanosheets was exfoliated under appropriate conditions, producing colloidal aqueous dispersions (ZPGly-e) which were then loaded with zinc (Zn/ZPGly) or silver ions. Silver ions were subsequently reduced to produce metallic silver nanoparticles on exfoliated ZPGly nanosheets (Ag@ZPGly).

New Parameters to Quantitatively Express the Invasiveness of Bacterial Strains from Implant-Related Orthopaedic Infections into Osteoblast Cells.

Complete eradication of bacterial infections is often a challenging task, especially in presence of prosthetic devices. Invasion of non-phagocytic host cells appears to be a critical mechanism of microbial persistence in host tissues. Hidden within host cells, bacteria elude host defences and antibiotic treatments that are intracellularly inactive.

Molecular Characterization of a Prevalent Ribocluster of Methicillin-Sensitive Staphylococcus aureus from Orthopedic Implant Infections. Correspondence with MLST CC30.

Staphylococcus aureus is the leading etiologic agent of orthopedic implant infections. Here a ribocluster of 27 S. aureus strains underwent further molecular characterization and subtyping by multilocus sequence typing (MLST) and spa-typing.

Orthopedic implant infections: Incompetence of Staphylococcus epidermidis, Staphylococcus lugdunensis, and Enterococcus faecalis to invade osteoblasts.

Septic failure is still the major complication of prosthetic implants. Entering host cells, bacteria hide from host immune defenses, shelter from extracellular antibiotics, and cause chronic infection. Staphylococcus aureus, the leading etiologic agent of orthopedic implant infections, is able to enter bone cells and induce osteoblast apoptosis, osteoclast recruitment, and highly destructive osteomyelitis.

Polysaccharide intercellular adhesin in biofilm: structural and regulatory aspects.

Staphylococcus aureus and Staphylococcus epidermidis are the leading etiologic agents of implant-related infections. Biofilm formation is the main pathogenetic mechanism leading to the chronicity and irreducibility of infections. The extracellular polymeric substances of staphylococcal biofilms are the polysaccharide intercellular adhesin (PIA), extracellular-DNA, proteins, and amyloid fibrils.

Staphylococcus lugdunensis, an aggressive coagulase-negative pathogen not to be underestimated.

The new emerging coagulase-negative pathogen Staphylococcus lugdunensis is responsible for severe cardiac and joint infections. Since the biochemical phenotypic systems designed for the identification of CoNS do not appear to be species specific and are hardly reliable for the discrimination of S. lugdunensis from other staphylococci, its precise identification requires fine molecular methods.

Biofilm extracellular-DNA in 55 Staphylococcus epidermidis clinical isolates from implant infections.

Biofilm formation is broadly recognized as an important virulence factor in many bacterial species implicated in implant-related opportunistic infections. In spite of a long history of research and many investigative efforts aimed at elucidating their chemical composition, structure, and function, the nature of bacterial biofilms still remains only partly revealed. Over the years, different extracellular polymeric substances (EPS) have been described that contribute functionally and structurally to the organization of biofilms.

Exopolysaccharide production by Staphylococcus epidermidis and its relationship with biofilm extracellular DNA.

Implant-related infections are difficult to treat because they are very often associated with biofilm-forming micro-organisms capable of resisting host immune defenses and surviving conventional antibiotic treatments. In Staphylococcus epidermidis biofilm-forming strains, the polysaccharide intercellular adhesin (PIA), whose expression is encoded by the icaADBC operon, is recognized as a main staphylococcal accumulation mechanism. Nevertheless, various observations have shown that PIA expression is dispensable and a variety of additional/alternative accumulation mechanisms, including extracellular DNA (eDNA) and several other factors of proteic nature, can compensate for icaADBC low expression or even for its absence.

Extracellular DNA in biofilms.

Extracellular DNA (eDNA) is an important biofilm component that was recently discovered. Its presence has been initially observed in biofilms of Pseudomonas aeruginosa, Streptococcus intermedius, Streptococcus mutans, then Enterococcus faecalis and staphylococci. Autolysis is the common mechanism by which eDNA is released.

Scenery of Staphylococcus implant infections in orthopedics.

Infection is still the major complication of orthopedic implants and projections based on the actual trend indicate that total hip and knee arthroplasties and their consequent infection burden are destined to greatly increase. Staphylococcus aureus and Staphylococcus epidermidis are the leading etiologic agents of orthopedic implant infection. Here we report on epidemiology of implant-related Staphylococcus infections in orthopedics, also referring to our experience, and focus on the crucial role of bacterial adhesins and on their ability to direct the pathogenesis process.

Polymorphisms of agr locus correspond to distinct genetic patterns of virulence in Staphylococcus aureus clinical isolates from orthopedic implant infections.

Staphylococcus aureus is the leading etiologic agent of orthopedic implant infections. It is endowed with the accessory gene regulator (agr) locus that modulates expression of many virulence genes. Four allelic groups of agr have been recognized within this bacterial species.

Panton-Valentine leukocidin gene detected in Staphylococcus aureus strain isolated from a knee arthroprosthesis infection.

This report focuses on the molecular characterization of a Staphylococcus aureus strain isolated from a knee arthroprosthesis infection and recognized retrospectively as a carrier of the Panton-Valentine leukocidin gene. The stored microbiological isolate, which belonged to the strain collection of the Research Unit on Implant Infections of the Rizzoli Orthopaedic Institute, was retrieved for molecular analysis. Genotyping was carried out, revealing an interesting profile.