# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 4045 | 0 | 1.0000 | Bacterial resistance to antimicrobial agents and its impact on veterinary and human medicine. BACKGROUND: Antimicrobial resistance has become a major challenge in veterinary medicine, particularly in the context of bacterial pathogens that play a role in both humans and animals. OBJECTIVES: This review serves as an update on acquired resistance mechanisms in bacterial pathogens of human and animal origin, including examples of transfer of resistant pathogens between hosts and of resistance genes between bacteria. RESULTS: Acquired resistance is based on resistance-mediating mutations or on mobile resistance genes. Although mutations are transferred vertically, mobile resistance genes are also transferred horizontally (by transformation, transduction or conjugation/mobilization), contributing to the dissemination of resistance. Mobile genes specifying any of the three major resistance mechanisms - enzymatic inactivation, reduced intracellular accumulation or modification of the cellular target sites - have been found in a variety of bacteria that may be isolated from animals. Such resistance genes are associated with plasmids, transposons, gene cassettes, integrative and conjugative elements or other mobile elements. Bacteria, including zoonotic pathogens, can be exchanged between animals and humans mainly via direct contact, but also via dust, aerosols or foods. Proof of the direction of transfer of resistant bacteria can be difficult and depends on the location of resistance genes or mutations in the chromosomal DNA or on a mobile element. CONCLUSION: The wide variety in resistance and resistance transfer mechanisms will continue to ensure the success of bacterial pathogens in the future. Our strategies to counteract resistance and preserve the efficacy of antimicrobial agents need to be equally diverse and resourceful. | 2017 | 27581211 |
| 4046 | 1 | 1.0000 | Horizontal Gene Transfer and Its Association with Antibiotic Resistance in the Genus Aeromonas spp. The evolution of multidrug resistant bacteria to the most diverse antimicrobials known so far pose a serious problem to global public health. Currently, microorganisms that develop resistant phenotypes to multiple drugs are associated with high morbidity and mortality. This resistance is encoded by a group of genes termed 'bacterial resistome', divided in intrinsic and extrinsic resistome. The first one refers to the resistance displayed on an organism without previous exposure to an antibiotic not involving horizontal genetic transfer, and it can be acquired via mutations. The latter, on the contrary, is acquired exclusively via horizontal genetic transfer involving mobile genetic elements that constitute the 'bacterial mobilome'. This transfer is mediated by three different mechanisms: transduction, transformation, and conjugation. Recently, a problem of public health due to implications in the emergence of multi-drug resistance in Aeromonas spp. strains in water environments has been described. This is derived from the genetic material transfer via conjugation events. This is important, since bacteria that have acquired antibiotic resistance in natural environments can cause infections derived from their ingestion or direct contact with open wounds or mucosal tissue, which in turn, by their resistant nature, makes their eradication complex. Implications of the emergence of resistance in Aeromonas spp. by horizontal gene transfer on public health are discussed. | 2019 | 31540466 |
| 4240 | 2 | 0.9999 | Genetics of antimicrobial resistance. Antimicrobial resistant strains of bacteria are an increasing threat to animal and human health. Resistance mechanisms to circumvent the toxic action of antimicrobials have been identified and described for all known antimicrobials currently available for clinical use in human and veterinary medicine. Acquired bacterial antibiotic resistance can result from the mutation of normal cellular genes, the acquisition of foreign resistance genes, or a combination of these two mechanisms. The most common resistance mechanisms employed by bacteria include enzymatic degradation or alteration of the antimicrobial, mutation in the antimicrobial target site, decreased cell wall permeability to antimicrobials, and active efflux of the antimicrobial across the cell membrane. The spread of mobile genetic elements such as plasmids, transposons, and integrons has greatly contributed to the rapid dissemination of antimicrobial resistance among several bacterial genera of human and veterinary importance. Antimicrobial resistance genes have been shown to accumulate on mobile elements, leading to a situation where multidrug resistance phenotypes can be transferred to a susceptible recipient via a single genetic event. The increasing prevalence of antimicrobial resistant bacterial pathogens has severe implications for the future treatment and prevention of infectious diseases in both animals and humans. The versatility with which bacteria adapt to their environment and exchange DNA between different genera highlights the need to implement effective antimicrobial stewardship and infection control programs in both human and veterinary medicine. | 2006 | 17127523 |
| 4043 | 3 | 0.9999 | Mobile antibiotic resistance - the spread of genes determining the resistance of bacteria through food products. In recent years, more and more antibiotics have become ineffective in the treatment of bacterial nfections. The acquisition of antibiotic resistance by bacteria is associated with circulation of genes in the environment. Determinants of antibiotic resistance may be transferred to pathogenic bacteria. It has been shown that conjugation is one of the key mechanisms responsible for spread of antibiotic resistance genes, which is highly efficient and allows the barrier to restrictions and modifications to be avoided. Some conjugative modules enable the transfer of plasmids even between phylogenetically distant bacterial species. Many scientific reports indicate that food is one of the main reservoirs of these genes. Antibiotic resistance genes have been identified in meat products, milk, fruits and vegetables. The reason for such a wide spread of antibiotic resistance genes is the overuse of antibiotics by breeders of plants and animals, as well as by horizontal gene transfer. It was shown, that resistance determinants located on mobile genetic elements, which are isolated from food products, can easily be transferred to another niche. The antibiotic resistance genes have been in the environment for 30 000 years. Their removal from food products is not possible, but the risks associated with the emergence of multiresistant pathogenic strains are very large. The only option is to control the emergence, selection and spread of these genes. Therefore measures are sought to prevent horizontal transfer of genes. Promising concepts involve the combination of developmental biology, evolution and ecology in the fight against the spread of antibiotic resistance. | 2016 | 27383577 |
| 4047 | 4 | 0.9999 | Integron involvement in environmental spread of antibiotic resistance. The spread of antibiotic-resistant bacteria is a growing problem and a public health issue. In recent decades, various genetic mechanisms involved in the spread of resistance genes among bacteria have been identified. Integrons - genetic elements that acquire, exchange, and express genes embedded within gene cassettes (GC) - are one of these mechanisms. Integrons are widely distributed, especially in Gram-negative bacteria; they are carried by mobile genetic elements, plasmids, and transposons, which promote their spread within bacterial communities. Initially studied mainly in the clinical setting for their involvement in antibiotic resistance, their role in the environment is now an increasing focus of attention. The aim of this review is to provide an in-depth analysis of recent studies of antibiotic-resistance integrons in the environment, highlighting their potential involvement in antibiotic-resistance outside the clinical context. We will focus particularly on the impact of human activities (agriculture, industries, wastewater treatment, etc.). | 2012 | 22509175 |
| 4239 | 5 | 0.9999 | Bacterial resistance. Pathogenic bacteria remain adaptable to an increasingly hostile environment and a wider variety of more potent antibiotics. Organisms not intrinsically prepared for defense have been able to acquire resistance to newer antimicrobial agents. Chromosomal mutations alone cannot account for the rapid emergence and spread of antibiotic resistance. It has been established that plasmids and transposons are particularly important in the evolution of antibiotic-resistant bacteria. Plasmid- or transposon-mediated resistance provides the bacteria with pre-evolved genes refined to express high-level resistance. In particular, transposons can transfer these resistance determinants in diverse bacterial species, and nature provides in humans and animals large intestinal reservoirs in which such communications are facilitated. Antibiotic therapy exerts selection pressures on bacteria. Eradication or marked reduction in the populations of susceptible organisms promotes the overgrowth of intrinsically resistant strains and favors those resistant as a result of favorable chromosomal mutations or via plasmids or transposons. In our hospitals, where antibiotic consumption continues to increase, the nosocomial flora consists of many resistant bacteria, and infections acquired in the nosocomial setting are now far more severe than their community-acquired counterparts. There is convincing evidence that infection control measures must take into further consideration the contribution of the hospital worker as carrier and mediator of antibiotic resistance. | 1991 | 1649425 |
| 4048 | 6 | 0.9999 | Mobile genetic elements in the genus Bacteroides, and their mechanism(s) of dissemination. Bacteroides spp organisms, the predominant commensal bacteria in the human gut have become increasingly resistant to many antibiotics. They are now also considered to be reservoirs of antibiotic resistance genes due to their capacity to harbor and disseminate these genes via mobile transmissible elements that occur in bewildering variety. Gene dissemination occurs within and from Bacteroides spp primarily by conjugation, the molecular mechanisms of which are still poorly understood in the genus, even though the need to prevent this dissemination is urgent. One current avenue of research is thus focused on interventions that use non-antibiotic methodologies to prevent conjugation-based DNA transfer. | 2011 | 22479685 |
| 9309 | 7 | 0.9999 | Plasmid encoded antibiotic resistance: acquisition and transfer of antibiotic resistance genes in bacteria. Bacteria have existed on Earth for three billion years or so and have become adept at protecting themselves against toxic chemicals. Antibiotics have been in clinical use for a little more than 6 decades. That antibiotic resistance is now a major clinical problem all over the world attests to the success and speed of bacterial adaptation. Mechanisms of antibiotic resistance in bacteria are varied and include target protection, target substitution, antibiotic detoxification and block of intracellular antibiotic accumulation. Acquisition of genes needed to elaborate the various mechanisms is greatly aided by a variety of promiscuous gene transfer systems, such as bacterial conjugative plasmids, transposable elements and integron systems, that move genes from one DNA system to another and from one bacterial cell to another, not necessarily one related to the gene donor. Bacterial plasmids serve as the scaffold on which are assembled arrays of antibiotic resistance genes, by transposition (transposable elements and ISCR mediated transposition) and site-specific recombination mechanisms (integron gene cassettes).The evidence suggests that antibiotic resistance genes in human bacterial pathogens originate from a multitude of bacterial sources, indicating that the genomes of all bacteria can be considered as a single global gene pool into which most, if not all, bacteria can dip for genes necessary for survival. In terms of antibiotic resistance, plasmids serve a central role, as the vehicles for resistance gene capture and their subsequent dissemination. These various aspects of bacterial resistance to antibiotics will be explored in this presentation. | 2008 | 18193080 |
| 4039 | 8 | 0.9999 | Acquired antibiotic resistance genes: an overview. In this review an overview is given on antibiotic resistance (AR) mechanisms with special attentions to the AR genes described so far preceded by a short introduction on the discovery and mode of action of the different classes of antibiotics. As this review is only dealing with acquired resistance, attention is also paid to mobile genetic elements such as plasmids, transposons, and integrons, which are associated with AR genes, and involved in the dispersal of antimicrobial determinants between different bacteria. | 2011 | 22046172 |
| 3834 | 9 | 0.9999 | What antimicrobial resistance has taught us about horizontal gene transfer. Horizontal gene transfer (HGT) has been responsible for the dissemination of numerous antimicrobial-resistance determinants throughout diverse bacterial species. The rapid and broad dissemination of resistance determinants by HGT, and subsequent selection for resistance imposed by the use of antimicrobials, threatens to undermine the usefulness of antimicrobials. However, vigilant surveillance of the emerging antimicrobial resistance in clinical settings and subsequent studies of resistant isolates create a powerful system for studying HGT and detecting rare events. Two of the most closely monitored phenotypes are resistance to beta-lactams and resistance to fluoroquinolones. Studies of resistance to these antimicrobials have revealed that (1) transformation occurs between different species of bacteria including some recipient species that were not previously known to be competent for natural transformation; (2) transduction may be playing an important role in generating novel methicillin-resistant Staphylococcus aureus (MRSA) strains, although the details of transferring the SCCmec element are not yet fully understood; (3) Resistance genes are probably moving to plasmids from chromosomes more rapidly than in the past; and (4) Resistance genes are aggregating upon plasmids. The linkage of numerous resistance genes on individual plasmids may underlie the persistence of resistance to specific antimicrobials even when use of those antimicrobials is discontinued. Further studies of HGT and methods for controlling HGT may be necessary to maintain the usefulness of antimicrobials. | 2009 | 19271198 |
| 4070 | 10 | 0.9999 | Antibiotic Resistance Mechanisms in Bacteria: Relationships Between Resistance Determinants of Antibiotic Producers, Environmental Bacteria, and Clinical Pathogens. Emergence of antibiotic resistant pathogenic bacteria poses a serious public health challenge worldwide. However, antibiotic resistance genes are not confined to the clinic; instead they are widely prevalent in different bacterial populations in the environment. Therefore, to understand development of antibiotic resistance in pathogens, we need to consider important reservoirs of resistance genes, which may include determinants that confer self-resistance in antibiotic producing soil bacteria and genes encoding intrinsic resistance mechanisms present in all or most non-producer environmental bacteria. While the presence of resistance determinants in soil and environmental bacteria does not pose a threat to human health, their mobilization to new hosts and their expression under different contexts, for example their transfer to plasmids and integrons in pathogenic bacteria, can translate into a problem of huge proportions, as discussed in this review. Selective pressure brought about by human activities further results in enrichment of such determinants in bacterial populations. Thus, there is an urgent need to understand distribution of resistance determinants in bacterial populations, elucidate resistance mechanisms, and determine environmental factors that promote their dissemination. This comprehensive review describes the major known self-resistance mechanisms found in producer soil bacteria of the genus Streptomyces and explores the relationships between resistance determinants found in producer soil bacteria, non-producer environmental bacteria, and clinical isolates. Specific examples highlighting potential pathways by which pathogenic clinical isolates might acquire these resistance determinants from soil and environmental bacteria are also discussed. Overall, this article provides a conceptual framework for understanding the complexity of the problem of emergence of antibiotic resistance in the clinic. Availability of such knowledge will allow researchers to build models for dissemination of resistance genes and for developing interventions to prevent recruitment of additional or novel genes into pathogens. | 2018 | 30555448 |
| 4072 | 11 | 0.9999 | A horizontal transmission of genetic information and its importance for development of antibiotics resistance. Genetic information is transmitted among organisms through two pathways - vertically from generation to generation (from parents to progeny) and horizontally (laterally) by direct exchange of genetic material across species barriers. These are primarily prokaryotes, in which the exchange of genes or whole gene segments by horizontal transmission is quite common. They can dynamically and in a relatively short time generate highly diverse genomes, which does not allow the vertical transmission. As a result, prokaryotes can rapidly acquire new properties such as virulence and pathogenicity as well as resistance to toxins, including antibiotics, by which they increase their adaptability. Therefore, reinfection-resistant microorganisms are always more difficult to treat than infections caused by non-resistant bacteria. Antibiotic resistance today is a global problem of health care service. Not only does the number of diseases caused by resistant pathogenic strains of bacteria increase, but also the cost of treatment increases disproportionately, the length of hospitalization is prolonged, and mortality is often rising. Therefore, when indicating antibiotic therapy, it is important to keep in mind that both overuse and abuse of antibiotics contribute to the spread of antibiotic resistance genes. This is equally true for antibiotic applications in veterinary medicine, agriculture, including aquacultures, or in the food industry. Keywords: horizontal transmission of genetic information, endosymbiosis, antibiotic resistance, risks of the emergence and spread of antibiotic resistance, prevention of antibiotic resistance. | 2018 | 30441943 |
| 4009 | 12 | 0.9999 | Unraveling the role of mobile genetic elements in antibiotic resistance transmission and defense strategies in bacteria. Irrational antibiotic use contributes to the development of antibiotic resistance in bacteria, which is a major cause of healthcare-associated infections globally. Molecular research has shown that multiple resistance frequently develops from the uptake of pre-existing resistance genes, which are subsequently intensified under selective pressures. Resistant genes spread and are acquired through mobile genetic elements which are essential for facilitating horizontal gene transfer. MGEs have been identified as carriers of genetic material and are a significant player in evolutionary processes. These include insertion sequences, transposons, integrative and conjugative elements, plasmids, and genomic islands, all of which can transfer between and within DNA molecules. With an emphasis on pathogenic bacteria, this review highlights the salient features of the MGEs that contribute to the development and spread of antibiotic resistance. MGEs carry non-essential genes, including AMR and virulence genes, which can enhance the adaptability and fitness of their bacterial hosts. These elements employ evolutionary strategies to facilitate their replication and dissemination, thus enabling survival without positive selection for the harboring of beneficial genes. | 2025 | 40810119 |
| 4044 | 13 | 0.9999 | Antibiotic resistance in food-related bacteria--a result of interfering with the global web of bacterial genetics. A series of antibiotic resistance genes have been sequenced and found to be identical or nearly identical in various ecological environments. Similarly, genetic vectors responsible for assembly and mobility of antibiotic resistance genes, such as transposons, integrons and R plasmids of similar or identical type are also widespread in various niches of the environment. Many zoonotic bacteria carry antibiotic resistance genes directly from different food-producing environments to the human being. These circumstances may have a major impact on the degree for success in treating infectious diseases in man. Several recent examples demonstrate that use of antibiotics in all parts of the food production chain contributes to the increasing level of antibiotic resistance among the food-borne pathogenic bacteria. Modern industrialized food production adds extra emphasis on lowering the use of antibiotics in all parts of agriculture, husbandry and fish farming because these food products are distributed to very large numbers of humans compared to more traditional smaller scale niche production. | 2002 | 12222637 |
| 4084 | 14 | 0.9999 | Bacteriophages Contribute to the Spread of Antibiotic Resistance Genes among Foodborne Pathogens of the Enterobacteriaceae Family - A Review. Foodborne illnesses continue to have an economic impact on global health care systems. There is a growing concern regarding the increasing frequency of antibiotic resistance in foodborne bacterial pathogens and how such resistance may affect treatment outcomes. In an effort to better understand how to reduce the spread of resistance, many research studies have been conducted regarding the methods by which antibiotic resistance genes are mobilized and spread between bacteria. Transduction by bacteriophages (phages) is one of many horizontal gene transfer mechanisms, and recent findings have shown phage-mediated transduction to be a significant contributor to dissemination of antibiotic resistance genes. Here, we review the viability of transduction as a contributing factor to the dissemination of antibiotic resistance genes in foodborne pathogens of the Enterobacteriaceae family, including non-typhoidal Salmonella and Shiga toxin-producing Escherichia coli, as well as environmental factors that increase transduction of antibiotic resistance genes. | 2017 | 28676794 |
| 4133 | 15 | 0.9999 | Importance of integrons in the diffusion of resistance. Horizontal transfer of resistance genes is a successful mechanism for the transmission and dissemination of multiple drug resistance among bacterial pathogens. The impact of horizontally transmitted genetic determinants in the evolution of resistance is particularly evident when resistance genes are physically associated in clusters and transferred en bloc to the recipient cell. Recent advances in the molecular characterisation of antibiotic resistance mechanisms have highlighted the existence of genetic structures. called integrons, involved in the acquisition of resistance genes. These DNA elements have frequently been reported in multi-drug resistant strains isolated from animals and humans, and are located either on the bacterial chromosome or on broad-host-range plasmids. The role of integrons in the development of multiple resistance relies on their unique capacity to cluster and express drug resistance genes. Moreover, the spread of resistance genes among different replicons and their exchange between plasmid and bacterial chromosome are facilitated by the integration of integrons into transposable elements. The association of a highly efficient gene capture and expression system, together with the capacity for vertical and horizontal transmission of resistance genes represents a powerful weapon used by bacteria to combat the assault of antibiotics. | 2001 | 11432416 |
| 4071 | 16 | 0.9999 | Antibiotic resistance in the environment: a link to the clinic? The emergence of resistance to all classes of antibiotics in previously susceptible bacterial pathogens is a major challenge to infectious disease medicine. The origin of the genes associated with resistance has long been a mystery. There is a growing body of evidence that is demonstrating that environmental microbes are highly drug resistant. The genes that make up this environmental resistome have the potential to be transferred to pathogens and indeed there is some evidence that at least some clinically relevant resistance genes have originated in environmental microbes. Understanding the extent of the environmental resistome and its mobilization into pathogenic bacteria is essential for the management and discovery of antibiotics. | 2010 | 20850375 |
| 9696 | 17 | 0.9999 | Evolution of resistance in microorganisms of human origin. Resistance to antimicrobials in bacteria results from either evolution of "new" DNA or from variation in existing DNA. Evidence suggests that new DNA did not originate since the use of antibiotics in medicine, but evolved long ago in soil bacteria. This evidence is based on functional and structural homologies of resistance proteins in human pathogens, and resistance proteins or physiological proteins of soil bacteria. Variation in existing DNA has been shown to comprise variations in structural or regulatory genes of the normal chromosome or mutations in already existing plasmid-mediated resistance genes modifying the resistance phenotype. The success of R-determinants in human pathogens was due to their horizontal spread by transformation, transduction and conjugation. Furthermore, transposition has enabled bacteria to efficiently distribute R-determinants between independent DNA-molecules. Since the genetic processes involved in the development of resistance are rare events, the selective pressure exerted by antibiotics has significantly contributed to the overall evolutionary picture. With few exceptions, experimental data about the role of antibiotic usage outside human medicine with respect to the resistance problem in human pathogens are missing. Epidemiological data about the occurrence of resistance in human pathogens seem to indicate that the major contributing factor to the problem we face today was the extensive use of antibiotics in medicine itself. | 1993 | 8212510 |
| 4058 | 18 | 0.9999 | Antimicrobial resistance: a complex issue. The discovery of antibiotics represented a turning point in human history. However, by the late 1950s infections that were difficult to treat, involving resistant bacteria, were being reported. Nowadays, multiresistant strains have become a major concern for public and animal health. Antimicrobial resistance is a complex issue, linked to the ability of bacteria to adapt quickly to their environment. Antibiotics, and antimicrobial-resistant bacteria and determinants, existed before the discovery and use of antibiotics by humans. Resistance to antimicrobial agents is a tool that allows bacteria to survive in the environment, and to develop. Resistance genes can be transferred between bacteria by horizontal transfer involving three mechanisms: conjugation, transduction and transformation. Resistant bacteria can emerge in any location when the appropriate conditions develop. Antibiotics represent a powerful selector for antimicrobial resistance in bacteria. Reducing the use of antimicrobial drugs is one way to control antimicrobial resistance; however, a full set of measures needs to be implemented to achieve this aim. | 2012 | 22849265 |
| 3833 | 19 | 0.9999 | Fight evolution with evolution: plasmid-dependent phages with a wide host range prevent the spread of antibiotic resistance. The emergence of pathogenic bacteria resistant to multiple antibiotics is a serious worldwide public health concern. Whenever antibiotics are applied, the genes encoding for antibiotic resistance are selected for within bacterial populations. This has led to the prevalence of conjugative plasmids that carry resistance genes and can transfer themselves between diverse bacterial groups. In this study, we investigated whether it is feasible to attempt to prevent the spread of antibiotic resistances with a lytic bacteriophage, which can replicate in a wide range of gram-negative bacteria harbouring conjugative drug resistance-conferring plasmids. The counter-selection against the plasmid was shown to be effective, reducing the frequency of multidrug-resistant bacteria that formed via horizontal transfer by several orders of magnitude. This was true also in the presence of an antibiotic against which the plasmid provided resistance. Majority of the multiresistant bacteria subjected to phage selection also lost their conjugation capability. Overall this study suggests that, while we are obligated to maintain the selection for the spread of the drug resistances, the 'fight evolution with evolution' approach could help us even out the outcome to our favour. | 2013 | 24062801 |