Bacterial biofilm formation on implantable devices and approaches to its treatment and prevention

Efficacy of antiseptic-impregnated central venous catheters in preventing catheter-related bloodstream infection. A Meta-analysis

Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs. Bacterial biofilm formation is a complex process and can be described in five main phases: (i) reversible attachment phase, where bacteria non-specifically attach to surfaces; (ii) irreversible attachment phase, which involves interaction between bacterial cells and a surface using bacterial adhesins such as fimbriae and lipopolysaccharide (LPS); (iii) production of extracellular polymeric substances (EPS) by the resident bacterial cells; (iv) biofilm maturation phase, in which bacterial cells synthesize and release signaling molecules to sense the presence of each other, conducing to the formation of microcolony and maturation of biofilms; and (v) dispersal/detachment phase, where the bacterial cells depart biofilms and comeback to independent planktonic lifestyle. Biofilm formation is detrimental in healthcare, drinking water distribution systems, food, and marine industries, etc. As a result, current studies have been focused toward control and prevention of biofilms. In an effort to get rid of harmful biofilms, various techniques and approaches have been employed that interfere with bacterial attachment, bacterial communication systems (quorum sensing, QS), and biofilm matrixs. Biofilms, however, also offer beneficial roles in a variety of fields including applications in plant protection, bioremediation, wastewater treatment, and corrosion inhibition amongst others. Development of beneficial biofilms can be promoted through manipulation of adhesion surfaces, QS and environmental conditions. This review describes the events involved in bacterial biofilm formation, lists the negative and positive aspects associated with bacterial biofilms, elaborates the main strategies currently used to regulate establishment of harmful bacterial biofilms as well as certain strategies employed to encourage formation of beneficial bacterial biofilms, and highlights the future perspectives of bacterial biofilms.

/pdf/beyond-risk-bacterial-biofilms-and-their-regulating-4xnboj91j5.pdf

Beyond Risk: Bacterial Biofilms and Their Regulating Approaches.

Orthopaedic and dental implants have become a staple of the medical industry and with an ageing population and growing culture for active lifestyles, this trend is forecast to continue. In accordance with the increased demand for implants, failure rates, particularly those caused by bacterial infection, need to be reduced. The past two decades have led to developments in antibiotics and antibacterial coatings to reduce revision surgery and death rates caused by infection. The limited effectiveness of these approaches has spurred research into nano-textured surfaces, designed to mimic the bactericidal properties of some animal, plant and insect species, and their topographical features. This review discusses the surface structures of cicada, dragonfly and butterfly wings, shark skin, gecko feet, taro and lotus leaves, emphasising the relationship between nano-structures and high surface contact angles on self-cleaning and bactericidal properties. Comparison of these surfaces shows large variations in structure dimension and configuration, indicating that there is no one particular surface structure that exhibits bactericidal behaviour against all types of microorganisms. Recent bio-mimicking fabrication methods are explored, finding hydrothermal synthesis to be the most commonly used technique, due to its environmentally friendly nature and relative simplicity compared to other methods. In addition, current proposed bactericidal mechanisms between bacteria cells and nano-textured surfaces are presented and discussed. These models could be improved by including additional parameters such as biological cell membrane properties, adhesion forces, bacteria dynamics and nano-structure mechanical properties. This paper lastly reviews the mechanical stability and cytotoxicity of micro and nano-structures and materials. While the future of nano-biomaterials is promising, long-term effects of micro and nano-structures in the body must be established before nano-textures can be used on orthopaedic implant surfaces as way of inhibiting bacterial adhesion.

/pdf/bio-mimicking-nano-and-micro-structured-surface-fabrication-46zirno7cx.pdf

Bio-mimicking nano and micro-structured surface fabrication for antibacterial properties in medical implants.

Human safety and well-being is threatened by microbes causing numerous infectious diseases resulting in a large number of deaths every year. Despite substantial progress in antimicrobial drugs, many infectious diseases remain difficult to treat. Antimicrobial polymers offer a promising antimicrobial strategy for fighting pathogens and have received considerable attention in both academic and industrial research. This mini-review presents the advances made in antimicrobial polymers since 2013. Antimicrobial mechanisms exhibiting either passive or active action and polymer material types containing bound or leaching antimicrobials are introduced. This article also addresses the applications of these antimicrobial polymers in the medical, food, and textile industries.

/pdf/recent-advances-in-antimicrobial-polymers-a-mini-review-4zzs2p3j03.pdf

Recent Advances in Antimicrobial Polymers: A Mini-Review.

Biofilms are a complex group of microbial cells that adhere to the exopolysaccharide matrix present on the surface of medical devices. Biofilm-associated infections in the medical devices pose a serious problem to the public health and adversely affect the function of the device. Medical implants used in oral and orthopedic surgery are fabricated using alloys such as stainless steel and titanium. The biological behavior, such as osseointegration and its antibacterial activity, essentially depends on both the chemical composition and the morphology of the surface of the device. Surface treatment of medical implants by various physical and chemical techniques are attempted in order to improve their surface properties so as to facilitate bio-integration and prevent bacterial adhesion. The potential source of infection of the surrounding tissue and antimicrobial strategies are from bacteria adherent to or in a biofilm on the implant which should prevent both biofilm formation and tissue colonization. This article provides an overview of bacterial biofilm formation and methods adopted for the inhibition of bacterial adhesion on medical implants.

/pdf/bacterial-adherence-and-biofilm-formation-on-medical-3fbdf078z3.pdf

Bacterial adherence and biofilm formation on medical implants: A review

Zirconia has its place in the biomedical industry because of its mechanical strength, bio-inertness, and physiochemical properties. Zirconia was synthesized and doped with Terbium (Tb), a lanthanide that was reported to show a photoluminescence property, which was a major characteristic for carcinogenic studies. Zirconia and Tb doped Zirconia were synthesized using the co-precipitation technique and were sintered at a temperature ranging from 900 to 1200 °C. The Zirconia sample and Tb doped Zirconia were thus studied for structural diversities using the X-ray powder diffraction technique (XRD), FTIR, FE-SEM, and TEM. From XRD, Zirconia phase transformation from monoclinic to tetragonal phase was observed, which signified limited fracture, elasticity, and crack formation. It was evident that Terbium stabilized the tetragonal phase of Zirconia, which reportedly shows mechanical properties, which include fracture toughness and flexural strength. The particle size of the Zirconia was comparatively more than the Tb doped Zirconia. The particle size of Zirconia ranged between 176 nm and 393 nm and the particle size of Tb doped Zirconia ranged between 110 nm and 343 nm. The biocompatibility of both the samples was tested using an Mg-63 cell line, and the cell viability was observed to be higher in Tb doped Zirconia when compared to the undoped Zirconia sample.

/pdf/microstructural-analysis-of-terbium-doped-zirconia-and-its-ea6td8uw.pdf

Suganathan Veerachamy

Papers

Bacterial adherence and biofilm formation on medical implants: A review

Microstructural Analysis of Terbium Doped Zirconia and Its Biological Studies