Anti-biofilm Activity as a Health Issue
TL;DR: The mechanisms of natural bacterial anti-biofilm strategies/mechanisms recently identified in pathogenic, commensal and probiotic bacteria and the main synthetic strategies used in clinical practice are compared and discussed, particularly for catheter-related infections.
Abstract: The formation and persistence of surface-attached microbial communities, known as biofilms, are responsible for 75% of human microbial infections (National Institutes of Health). Biofilm lifestyle confers several advantages to the pathogens, notably during the colonization process of medical devices and/or patients’ organs. In addition, sessile bacteria have a high tolerance to exogenous stress including anti-infectious agents. Biofilms are highly competitive communities and some microorganisms exhibit anti-biofilm capacities such as bacterial growth inhibition, exclusion or competition, which enable them to acquire advantages and become dominant. The deciphering and control of anti-biofilm properties represent future challenges in human infection control. The aim of this review is to compare and discuss the mechanisms of natural bacterial anti-biofilm strategies/mechanisms recently identified in pathogenic, commensal and probiotic bacteria and the main synthetic strategies used in clinical practice, particularly for catheter-related infections.
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TL;DR: Basic methods used to study QS/QQ, as well as the medical and biotechnological applications of QQ, are described.
Abstract: Quorum sensing (QS) is a mechanism that enables microbial communication. It is based on the constant secretion of signaling molecules to the environment. The main role of QS is the regulation of vital processes in the cell such as virulence factor production or biofilm formation. Due to still growing bacterial resistance to antibiotics that have been overused, it is necessary to search for alternative antimicrobial therapies. One of them is quorum quenching (QQ) that disrupts microbial communication. QQ-driving molecules can decrease or even completely inhibit the production of virulence factors (including biofilm formation). There are few QQ strategies that comprise the use of the structural analogues of QS receptor autoinductors (AI). They may be found in nature or be designed and synthesized via chemical engineering. Many of the characterized QQ molecules are enzymes with the ability to degrade signaling molecules. They can also impede cellular signaling cascades. There are different techniques used for testing QS/QQ, including chromatography-mass spectroscopy, bioluminescence, chemiluminescence, fluorescence, electrochemistry, and colorimetry. They all enable qualitative and quantitative measurements of QS/QQ molecules. This article gathers the information about the mechanisms of QS and QQ, and their effect on microbial biofilm formation. Basic methods used to study QS/QQ, as well as the medical and biotechnological applications of QQ, are also described. Basis research methods are also described as well as medical and biotechnological application.
184 citations
Cites background from "Anti-biofilm Activity as a Health I..."
...The ability to produce biofilm, i.e., the spatial structure surrounded by the extracellular matrix (EPS), increases protection of microbial cells against harmful factors (Miquel et al. 2016)....
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..., the spatial structure surrounded by the extracellular matrix (EPS), increases protection of microbial cells against harmful factors (Miquel et al. 2016)....
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TL;DR: The present review emphasizes the synthesis methods, modes of action under dissipative conditions and the various biomedical applications of AgNPs in detail.
Abstract: Generally, silver is considered as a noble metal used for treating burn wound infections, open wounds and cuts However, the emerging nanotechnology has made a remarkable impact by converting metallic silver into silver nanoparticles (AgNPs) for better applications The advancement in technology has improved the synthesis of NPs using biological method instead of physical and chemical methods Nonetheless, synthesizing AgNPs using biological sources is ecofriendly and cost effective Till date, AgNPs are widely used as antibacterial agents; therefore, a novel idea is needed for the successful use of AgNPs as therapeutic agents to uncertain diseases and infections In biomedicine, AgNPs possess significant advantages due to their physical and chemical versatility Indeed, the toxicity concerns regarding AgNPs have created the need for non-toxic and ecofriendly approaches to produce AgNPs The applications of AgNPs in nanogels, nanosolutions, silver based dressings and coating over medical devices are under progress Still, an improvised version of AgNPs for extended applications in an ecofriendly manner is the need of the hour Therefore, the present review emphasizes the synthesis methods, modes of action under dissipative conditions and the various biomedical applications of AgNPs in detail
152 citations
TL;DR: The antimicrobial,anti-quorum sensing, anti-biofilm and anti-enterotoxin activities, of plant phenolic extracts and compounds are discussed, with special attention to pathogen microorganisms that have food relation.
Abstract: Phenolic compounds and extracts with bioactive properties can be obtained from many kinds of plant materials. These natural substances have gained attention in the food research as possible growth inhibitors of foodborne pathogenic and spoilage bacteria. Many phenolic-enriched plant extracts and individual phenolics have promising anti-quorum sensing potential as well and can suppress the biofilm formation and toxin production of food-related pathogens. Various studies have shown that plant phenolics can substitute or support the activity of synthetic food preservatives and disinfectants, which, by the way, can provoke serious concerns in consumers. In this review, we will provide a brief insight into the bioactive properties, i.e., the antimicrobial, anti-quorum sensing, anti-biofilm and anti-enterotoxin activities, of plant phenolic extracts and compounds, with special attention to pathogen microorganisms that have food relation. Carbohydrase aided applications to improve the antimicrobial properties of phenolic extracts are also discussed.
144 citations
Cites background from "Anti-biofilm Activity as a Health I..."
...In addition, the antimicrobial substances at subinhibitory concentration can act as environmental signals activating the formation of biofilms [100], thereby, leading to the failure of the drug treatment [101]....
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TL;DR: In light of the current body of knowledge, it was suggested that dispersal acts as a potent means of disseminating bacteria with enhanced colonization properties in the surrounding environment.
Abstract: In most environments, microorganisms evolve in a sessile mode of growth, designated as biofilm, which is characterized by cells embedded in a self-produced extracellular matrix. Although a biofilm is commonly described as a "cozy house" where resident bacteria are protected from aggression, bacteria are able to break their biofilm bonds and escape to colonize new environments. This regulated process is observed in a wide variety of species; it is referred to as biofilm dispersal, and is triggered in response to various environmental and biological signals. The first part of this review reports the main regulatory mechanisms and effectors involved in biofilm dispersal. There is some evidence that dispersal is a necessary step between the persistence of bacteria inside biofilm and their dissemination. In the second part, an overview of the main methods used so far to study the dispersal process and to harvest dispersed bacteria was provided. Then focus was on the properties of the biofilm-dispersed bacteria and the fundamental role of the dispersal process in pathogen dissemination within a host organism. In light of the current body of knowledge, it was suggested that dispersal acts as a potent means of disseminating bacteria with enhanced colonization properties in the surrounding environment.
140 citations
Cites background from "Anti-biofilm Activity as a Health I..."
...According to the National Institutes of Health, about 65% of all microbial infections, and 80% of chronic infections are associated with biofilms (Hall et al., 2014; Miquel et al., 2016)....
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TL;DR: This review is a brief overview of biofilm research and provides updates on recent understandings on biofilm development, antibiotic resistance and transmission, and importance of QS mechanisms.
Abstract: Biofilm is a mode of living employed by many pathogenic and environmental microbes to proliferate as multicellular aggregates on inert inanimate or biological substrates. Several microbial diseases are associated with biofilms that pose challenges in treatment with antibiotics targeting individual cells. Bacteria in biofilms secrete exopolymeric substances that contribute to architectural stability and provide a secure niche to inhabiting cells. Quorum sensing (QS) plays essential roles in biofilm development. Pathogenic bacteria in biofilms utilize QS mechanisms to activate virulence and develop antibiotic resistance. This review is a brief overview of biofilm research and provides updates on recent understandings on biofilm development, antibiotic resistance and transmission, and importance of QS mechanisms. Strategies to combat biofilm associated diseases including anti-biofilm substances, quorum quenching molecules, bio-surfactants and competitive inhibitors are briefly discussed. The review concludes with updates on recent approaches utilized for biofilm inhibition and provides perspectives for further research in the field.
124 citations
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TL;DR: Improvements in understanding of the genetic and molecular basis of bacterial community behavior point to therapeutic targets that may provide a means for the control of biofilm infections.
Abstract: Bacteria that attach to surfaces aggregate in a hydrated polymeric matrix of their own synthesis to form biofilms. Formation of these sessile communities and their inherent resistance to antimicrobial agents are at the root of many persistent and chronic bacterial infections. Studies of biofilms have revealed differentiated, structured groups of cells with community properties. Recent advances in our understanding of the genetic and molecular basis of bacterial community behavior point to therapeutic targets that may provide a means for the control of biofilm infections.
11,162 citations
"Anti-biofilm Activity as a Health I..." refers background in this paper
...They are involved in specific infectious diseases such as osteomyelitis, otitis media, peridontitis, and dental caries (Costerton et al., 1999) and in chronic diseases such as pulmonary infections of cystic fibrosis patients....
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...Biofilms were initially defined as structured communities of bacterial cells enclosed in self-produced polymeric matrices and adherent to inert or living surfaces (Costerton et al., 1999)....
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TL;DR: It is understood that biofilms are universal, occurring in aquatic and industrial water systems as well as a large number of environments and medical devices relevant for public health, and that treatments may be based on inhibition of genes involved in cell attachment and biofilm formation.
Abstract: Though biofilms were first described by Antonie van Leeuwenhoek, the theory describing the biofilm process was not developed until 1978. We now understand that biofilms are universal, occurring in aquatic and industrial water systems as well as a large number of environments and medical devices relevant for public health. Using tools such as the scanning electron microscope and, more recently, the confocal laser scanning microscope, biofilm researchers now understand that biofilms are not unstructured, homogeneous deposits of cells and accumulated slime, but complex communities of surface-associated cells enclosed in a polymer matrix containing open water channels. Further studies have shown that the biofilm phenotype can be described in terms of the genes expressed by biofilm-associated cells. Microorganisms growing in a biofilm are highly resistant to antimicrobial agents by one or more mechanisms. Biofilm-associated microorganisms have been shown to be associated with several human diseases, such as native valve endocarditis and cystic fibrosis, and to colonize a wide variety of medical devices. Though epidemiologic evidence points to biofilms as a source of several infectious diseases, the exact mechanisms by which biofilm-associated microorganisms elicit disease are poorly understood. Detachment of cells or cell aggregates, production of endotoxin, increased resistance to the host immune system, and provision of a niche for the generation of resistant organisms are all biofilm processes which could initiate the disease process. Effective strategies to prevent or control biofilms on medical devices must take into consideration the unique and tenacious nature of biofilms. Current intervention strategies are designed to prevent initial device colonization, minimize microbial cell attachment to the device, penetrate the biofilm matrix and kill the associated cells, or remove the device from the patient. In the future, treatments may be based on inhibition of genes involved in cell attachment and biofilm formation.
5,748 citations
"Anti-biofilm Activity as a Health I..." refers background in this paper
...These cells frequently express phenotypes different from their non-adherent planktonic counterparts, with a high capacity to colonize new surfaces and a high tolerance to exogenous stress (Donlan and Costerton, 2002; Macfarlane and Dillon, 2007)....
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...Biofilms are increasingly recognized by the public health community as an important source of pathogens (Donlan and Costerton, 2002; Wingender and Flemming, 2011)....
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TL;DR: An expert panel was convened in October 2013 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to discuss the field of probiotics and the appropriate use and scope of the term probiotic.
Abstract: An expert panel was convened in October 2013 by the International Scientific Association for Probiotics and Prebiotics (ISAPP) to discuss the field of probiotics. It is now 13 years since the definition of probiotics and 12 years after guidelines were published for regulators, scientists and industry by the Food and Agriculture Organization of the United Nations and the WHO (FAO/WHO). The FAO/WHO definition of a probiotic--"live microorganisms which when administered in adequate amounts confer a health benefit on the host"--was reinforced as relevant and sufficiently accommodating for current and anticipated applications. However, inconsistencies between the FAO/WHO Expert Consultation Report and the FAO/WHO Guidelines were clarified to take into account advances in science and applications. A more precise use of the term 'probiotic' will be useful to guide clinicians and consumers in differentiating the diverse products on the market. This document represents the conclusions of the ISAPP consensus meeting on the appropriate use and scope of the term probiotic.
5,114 citations
"Anti-biofilm Activity as a Health I..." refers background in this paper
...(ISAPP) as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” (Hill et al., 2014), have gained increasing medical attention because of their antagonist effects against numerous pathogens....
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TL;DR: These updated guidelines replace the previous management guidelines published in 2001 and are intended for use by health care providers who care for patients who either have these infections or may be at risk for them.
Abstract: These updated guidelines replace the previous management guidelines published in 2001. The guidelines are intended for use by health care providers who care for patients who either have these infections or may be at risk for them.
2,828 citations
"Anti-biofilm Activity as a Health I..." refers background in this paper
...Numerous data are now available to guide physicians in the choice of antibiotic lock solution components and their final concentrations (Mermel et al., 2009; Justo and Bookstaver, 2014)....
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TL;DR: All the available evidence suggests that multi-antibiotic resistant strains are as easily killed by PDT as naive strains, and that bacteria will not readily develop resistance to PDT.
Abstract: Photodynamic therapy (PDT) employs a non-toxic dye, termed a photosensitizer (PS), and low intensity visible light which, in the presence of oxygen, combine to produce cytotoxic species. PDT has the advantage of dual selectivity, in that the PS can be targeted to its destination cell or tissue and, in addition, the illumination can be spatially directed to the lesion. PDT has previously been used to kill pathogenic microorganisms in vitro, but its use to treat infections in animal models or patients has not, as yet, been much developed. It is known that Gram-(−) bacteria are resistant to PDT with many commonly used PS that will readily lead to phototoxicity in Gram-(+) species, and that PS bearing a cationic charge or the use of agents that increase the permeability of the outer membrane will increase the efficacy of killing Gram-(−) organisms. All the available evidence suggests that multi-antibiotic resistant strains are as easily killed by PDT as naive strains, and that bacteria will not readily develop resistance to PDT. Treatment of localized infections with PDT requires selectivity of the PS for microbes over host cells, delivery of the PS into the infected area and the ability to effectively illuminate the lesion. Recently, there have been reports of PDT used to treat infections in selected animal models and some clinical trials: mainly for viral lesions, but also for acne, gastric infection by Helicobacter pylori and brain abcesses. Possible future clinical applications include infections in wounds and burns, rapidly spreading and intractable soft-tissue infections and abscesses, infections in body cavities such as the mouth, ear, nasal sinus, bladder and stomach, and surface infections of the cornea and skin.
1,728 citations
"Anti-biofilm Activity as a Health I..." refers background in this paper
...The excitation of the photosensitizer by light generates reactive oxygen species (ROS), which leads to the oxidation of biomolecules of microorganisms and results in cell damage and death (Hamblin and Hasan, 2004)....
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