RESUMEN
In Norway, the use of quinolones in livestock populations is very low, and prophylactic use is prohibited. Despite this, quinolone-resistant Escherichia coli (QREC) isolates are present at low levels in several animal species. The source of these QREC isolates is unknown. The aim of this study was to characterize and compare QREC isolates from different animal species to identify putative factors that may promote the occurrence of QREC. A total of 280 QREC isolates, from broilers, pigs, red foxes, and wild birds, were whole-genome sequenced and analyzed. Well-known chromosomal and plasmid-mediated resistance mechanisms were identified. In addition, mutations in marR, marA, and rpoB causing novel amino acid substitutions in their respective proteins were detected. Phylogenetic analyses were used to determine the relationships between the isolates. Quinolone resistance mechanism patterns appeared to follow sequence type groups. Similar QREC isolates with similar resistance mechanism patterns were detected from the samples, and further phylogenetic analysis indicated close evolutionary relationships between specific isolates from different sources. This suggests the dissemination of highly similar QREC isolates between animal species and also the persistence of QREC strains within the broiler production chain. This highlights the importance of both control measures at the top of the production chain as well as biosecurity measures to avoid the further dissemination and persistence of QREC in these environments.IMPORTANCE Since antimicrobial usage is low in Norwegian animal husbandry, Norway is an ideal country to study antimicrobial resistance in the absence of selective pressure from antimicrobial usage. In particular, the usage of quinolones is very low, which makes it possible to investigate the spread and development of quinolone resistance in natural environments. Comparison of quinolone-resistant E. coli (QREC) isolates from livestock and wild animals in light of this low quinolone usage provides new insights into the development and dissemination of QREC in both natural and production environments. With this information, preventive measures may be taken to prevent further dissemination within Norwegian livestock and between other animals, thus maintaining the favorable situation in Norway.
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Pollos , Farmacorresistencia Bacteriana Múltiple , Infecciones por Escherichia coli/veterinaria , Escherichia coli/fisiología , Enfermedades de las Aves de Corral/microbiología , Quinolonas/farmacología , Enfermedades de los Porcinos/microbiología , Crianza de Animales Domésticos , Animales , Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Infecciones por Escherichia coli/microbiología , Vivienda para Animales , Noruega , Sus scrofa , PorcinosRESUMEN
(+)-N6-Hydroxyagelasine D, the enantiomer of the proposed structure of (-)-ageloxime D, as well as N6-hydroxyagelasine analogs were synthesized by selective N-7 alkylation of N6-[tert-butyl(dimethyl)silyloxy]-9-methyl-9H-purin-6-amine in order to install the terpenoid side chain, followed by fluoride mediated removal of the TBDMS-protecting group. N6-Hydroxyagelasine D and the analog carrying a geranylgeranyl side chain displayed profound antimicrobial activities against several pathogenic bacteria and protozoa and inhibited bacterial biofilm formation. However these compounds were also toxic towards mammalian fibroblast cells (MRC-5). The spectral data of N6-hydroxyagelasine D did not match those reported for ageloxime D before. Hence, a revised structure of ageloxime D was proposed. Basic hydrolysis of agelasine D gave (+)-N-[4-amino-6-(methylamino)pyrimidin-5-yl]-N-copalylformamide, a compound with spectral data in full agreement with those reported for (-)-ageloxime D.
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Antibacterianos/farmacología , Diterpenos/farmacología , Pirimidinas/farmacología , Antibacterianos/síntesis química , Antibacterianos/toxicidad , Biopelículas/efectos de los fármacos , Candida albicans/efectos de los fármacos , Línea Celular , Diterpenos/síntesis química , Diterpenos/toxicidad , Escherichia coli/efectos de los fármacos , Humanos , Pruebas de Sensibilidad Microbiana , Mycobacterium tuberculosis/efectos de los fármacos , Pirimidinas/síntesis química , Pirimidinas/toxicidad , Staphylococcus aureus/efectos de los fármacos , Trypanosomatina/efectos de los fármacosRESUMEN
Bacteria have the ability to adapt to changing environments through rapid evolution mediated by modification of existing genetic information, as well as by horizontal gene transfer (HGT). This makes bacteria a highly successful life form when it comes to survival. Unfortunately, this genetic plasticity may result in emergence and dissemination of antimicrobial resistance and virulence genes, and even the creation of multiresistant "superbugs" which may pose serious threats to public health. As bacteria commonly reside in biofilms, there has been an increased interest in studying these phenomena within biofilms in recent years. This review summarizes the present knowledge within this important area of research. Studies on bacterial evolution in biofilms have shown that mature biofilms develop into diverse communities over time. There is growing evidence that the biofilm lifestyle may be more mutagenic than planktonic growth. Furthermore, all three main mechanisms for HGT have been observed in biofilms. This has been shown to occur both within and between bacterial species, and higher transfer rates in biofilms than in planktonic cultures were detected. Of special concern are the observations that mutants with increased antibiotic resistance occur at higher frequency in biofilms than in planktonic cultures even in the absence of antibiotic exposure. Likewise, efficient dissemination of antimicrobial resistance genes, as well as virulence genes, has been observed within the biofilm environment. This new knowledge emphasizes the importance of biofilm awareness and control.
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Bacterias/crecimiento & desarrollo , Bacterias/genética , Biopelículas/crecimiento & desarrollo , Transferencia de Gen Horizontal , Variación Genética , Genotipo , Recombinación Genética , Farmacorresistencia Bacteriana , Evolución MolecularRESUMEN
Benzyl alcohol (BnOH) is widely used as a component of foods, cosmetics, household products and medical products. It is generally considered to be safe for human use, however, it has been connected to a number of adverse effects, including hypersensitivity reactions and neonatal deaths. BnOH is a membrane fluidizing agent that can affect membrane protein activity and cellular processes such as ligand binding to cell surface receptors, endocytosis and degradation of lysosomal cargo. In this study, we examined the effects of BnOH on intracellular transport using Shiga toxin (Stx), diphtheria toxin (DT) and ricin. BnOH caused reduced toxicity of all three toxins at BnOH concentrations that cause membrane fluidization. The reduced toxicity of Stx and ricin was mainly due to inhibition of retrograde transport between endosomes and the trans-Golgi network as BnOH had small effects on cell association and endocytosis of ricin and Stx. Strikingly, BnOH also induced a reversible fragmentation of the Golgi apparatus.
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Alcohol Bencilo/farmacología , Transporte Biológico/efectos de los fármacos , Endosomas/efectos de los fármacos , Aparato de Golgi/efectos de los fármacos , Red trans-Golgi/efectos de los fármacos , Movimiento Celular/efectos de los fármacos , Endocitosis/efectos de los fármacos , Endosomas/metabolismo , Aparato de Golgi/metabolismo , Células HeLa , Humanos , Transporte de Proteínas/efectos de los fármacos , Toxina Shiga/metabolismo , Red trans-Golgi/metabolismoRESUMEN
2-Deoxy-D-glucose (2DG) is a structural analogue of glucose with well-established applications as an inhibitor of glycolysis and N-glycosylation. Importantly, 2DG has been shown to improve the efficacy of several cancer chemotherapeutic agents in vivo and thus it is in clinical studies in combination with chemotherapy and radiotherapy. However, although 2DG has been demonstrated to modulate many cellular functions, including autophagy, apoptosis and cell cycle control, little is known about the effects of 2DG on intracellular transport, which is of great importance when predicting the effects of 2DG on therapeutic agents. In addition to proteins, lipids play important roles in cellular signalling and in controlling cellular trafficking. We have, in the present study, investigated the effects of 2DG on cellular lipid composition and by use of protein toxins we have studied 2DG-mediated changes in intracellular trafficking. By quantifying more than 200 individual lipid species from 17 different lipid classes, we have found that 2DG treatment changes the levels and/or species composition of several lipids, such as phosphatidylinositol (PI), diacylglycerol (DAG), cholesteryl ester (CE), ceramide (Cer) and lysophospho-lipids. Moreover, 2DG becomes incorporated into the carbohydrate moiety of glycosphingolipids (GSLs). In addition, we have discovered that 2DG protects cells against Shiga toxins (Stxs) and inhibits release of the cytotoxic StxA1 moiety in the endoplasmic reticulum (ER). The data indicate that the 2DG-induced protection against Stx is independent of inhibition of glycolysis or N-glycosylation, but rather mediated via the depletion of Ca(2+) from cellular reservoirs by 2DG. In conclusion, our results reveal novel actions of 2DG on cellular lipids and Stx toxicity.
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Citoprotección/efectos de los fármacos , Desoxiglucosa/farmacología , Lípidos de la Membrana/metabolismo , Toxinas Shiga/toxicidad , Línea Celular , Citoprotección/fisiología , HumanosRESUMEN
The ERM proteins (ezrin, radixin and moesin) are known for connecting the actin cytoskeleton to the plasma membrane. They have been found to associate with lipid rafts as well as to be important for endosomal sorting and receptor signaling. However, little is known about the role of ERM proteins in retrograde transport and lipid homeostasis. In this study, we show that ezrin and moesin are important for efficient cell surface association of Shiga toxin (Stx) as well as for its retrograde transport. Furthermore, we show that depletion of these proteins influences endosomal dynamics and seems to enhance Stx transport toward lysosomes. We also show that knockdown of Vps11, a subunit of the HOPS complex, leads to increased retrograde Stx transport and reverses the inhibiting effect of ezrin and moesin knockdown. Importantly, retrograde transport of the plant toxin ricin, which binds to both glycolipids and glycoproteins with a terminal galactose, seems to be unaffected by ezrin and moesin depletion.
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Proteínas del Citoesqueleto/metabolismo , Proteínas de Microfilamentos/metabolismo , Toxina Shiga/metabolismo , Membrana Celular/metabolismo , Proteínas del Citoesqueleto/genética , Endosomas/metabolismo , Células HeLa , Humanos , Lisosomas/metabolismo , Proteínas de Microfilamentos/genética , Transporte de Proteínas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Ricina/genética , Ricina/metabolismo , Toxina Shiga/genética , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismoRESUMEN
Flagella-mediated swimming and swarming motility in Salmonella enterica serovar Typhimurium is intercalated with the cyclic di-guanylate monophosphate (c-di-GMP) signalling network. In this study, we identified the GGDEF domain proteins STM2672, STM4551 and STM1987 as key di-guanylate cyclases involved in regulation of motility in a ΔyhjH phosphodiesterase gene deletion mutant with elevated c-di-GMP levels inhibiting motility. Surprisingly, these di-guanylate cyclases distinctively inhibited motility through the c-di-GMP receptors YcgR and the cellulose synthase BcsA, whereby STM2672 corresponded to YcgR, STM1987 to BcsA and STM4551 to both receptors. Although downregulation of motility is believed to prepare the bacterial cells for surface adhesion and biofilm formation, the major biofilm regulator CsgD of S. sv. Typhimurium was not involved in the regulation of swimming or swarming motility. Together with previously identified c-di-GMP networks regulating flagella-related phenotypes, flagella biosynthesis is a major target of c-di-GMP signalling in S. sv. Typhimurium.
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Biopelículas/crecimiento & desarrollo , GMP Cíclico/análogos & derivados , Flagelos/fisiología , Salmonella typhimurium/fisiología , Adhesión Bacteriana/genética , Proteínas Portadoras/metabolismo , GMP Cíclico/genética , GMP Cíclico/metabolismo , Flagelos/genética , Eliminación de Gen , Regulación Bacteriana de la Expresión Génica , Glucosiltransferasas/genética , Glucosiltransferasas/metabolismo , Hidrolasas Diéster Fosfóricas/genética , Estructura Terciaria de Proteína , Salmonella typhimurium/genética , Transactivadores/biosíntesisRESUMEN
Cell density is one of the extrinsic factors to which cells adapt their physiology when grown in culture. However, little is known about the molecular changes which occur during cell growth and how cellular responses are then modulated. In many cases, inhibitors, drugs or growth factors used for in vitro studies change the rate of cell proliferation, resulting in different cell densities in control and treated samples. Therefore, for a comprehensive data analysis, it is essential to understand the implications of cell density on the molecular level. In this study, we have investigated how lipid composition changes during cell growth, and the consequences it has for transport of Shiga toxin. By quantifying 308 individual lipid species from 17 different lipid classes, we have found that the levels and species distribution of several lipids change during cell growth, with the major changes observed for diacylglycerols, phosphatidic acids, cholesterol esters, and lysophosphatidylethanolamines. In addition, there is a reduced binding and retrograde transport of Shiga toxin in high density cells which lead to reduced intoxication by the toxin. In conclusion, our data provide novel information on how lipid composition changes during cell growth in culture, and how these changes can modulate intracellular trafficking.
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Recuento de Células , Metabolismo de los Lípidos , Sintaxina 1/metabolismo , Técnicas de Cultivo de Célula , Línea Celular Tumoral , Colesterol/metabolismo , Diglicéridos/metabolismo , Globósidos/metabolismo , Glicoesfingolípidos/metabolismo , Células HeLa , Células Hep G2 , Humanos , Lisofosfolípidos/metabolismo , Ácidos Fosfatidicos/metabolismo , Transporte de Proteínas , Toxina Shiga/metabolismo , Sintaxina 1/genética , Trihexosilceramidas/metabolismoRESUMEN
Shiga toxin-producing Escherichia coli bacteria cause hemorrhagic colitis and hemolytic uremic syndrome in humans. Currently, only supportive treatment is available for diagnosed patients. We show here that 24-h pretreatment with an ether lipid precursor, the alkylglycerol sn-1-O-hexadecylglycerol (HG), protects HEp-2 cells against Shiga toxin and Shiga toxin 2. Also the endothelial cell lines HMEC-1 and HBMEC are protected against Shiga toxins after HG pretreatment. In contrast, the corresponding acylglycerol, DL-α-palmitin, has no effect on Shiga toxicity. Although HG treatment provides a strong protection (~30 times higher IC50) against Shiga toxin, only a moderate reduction in toxin binding was observed, suggesting that retrograde transport of the toxin from the plasma membrane to the cytosol is perturbed. Furthermore, endocytosis of Shiga toxin and retrograde sorting from endosomes to the Golgi apparatus remain intact, but transport from the Golgi to the endoplasmic reticulum is inhibited by HG treatment. As previously described, HG reduces the total level of all quantified glycosphingolipids to 50-70% of control, including the Shiga toxin receptor globotriaosylceramide (Gb3), in HEp-2 cells. In accordance with this, we find that interfering with Gb3 biosynthesis by siRNA-mediated knockdown of Gb3 synthase for 24 h causes a similar cytotoxic protection and only a moderate reduction in toxin binding (to 70% of control cells). Alkylglycerols, including HG, have been administered to humans for investigation of therapeutic roles in disorders where ether lipid biosynthesis is deficient, as well as in cancer therapy. Further studies may reveal if HG can also have a therapeutic potential in Shiga toxin-producing E. coli infections.
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Glicerol/química , Éteres de Glicerilo/química , Toxinas Shiga/química , Transporte Biológico , Biotinilación , Línea Celular , Membrana Celular/metabolismo , Citosol/metabolismo , Endocitosis , Retículo Endoplásmico/metabolismo , Escherichia coli/metabolismo , Éter/química , Glicoesfingolípidos/química , Aparato de Golgi/metabolismo , Células HEK293 , Humanos , Concentración 50 Inhibidora , Lípidos/química , Ácido Palmítico/química , Toxina Shiga/química , Trihexosilceramidas/químicaRESUMEN
Eradicating biofouling from implant surfaces is essential in treating peri-implant infections, as it directly addresses the microbial source for infection and inflammation around dental implants. This controlled laboratory study examines the effectiveness of the four commercially available debridement solutions '(EDTA (Prefgel®), NaOCl (Perisolv®), H2O2 (Sigma-Aldrich) and Chlorhexidine (GUM® Paroex®))' in removing the acquired pellicle, preventing pellicle re-formation and removing of a multi-species oral biofilm growing on a titanium implant surface, and compare the results with the effect of a novel formulation of a peroxide-activated 'Poloxamer gel (Nubone® Clean)'. Evaluation of pellicle removal and re-formation was conducted using scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy to assess the surface morphology, elemental composition and chemical surface composition. Hydrophilicity was assessed through contact angle measurements. The multi-species biofilm model included Streptococcus oralis, Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans, reflecting the natural oral microbiome's complexity. Biofilm biomass was quantified using safranin staining, biofilm viability was evaluated using confocal laser scanning microscopy, and SEM was used for morphological analyses of the biofilm. Results indicated that while no single agent completely eradicated the biofilm, the 'Poloxamer gel' activated with 'H2O2' exhibited promising results. It minimized re-contamination of the pellicle by significantly lowering the contact angle, indicating enhanced hydrophilicity. This combination also showed a notable reduction in carbon contaminants, suggesting the effective removal of organic residues from the titanium surface, in addition to effectively reducing viable bacterial counts. In conclusion, the 'Poloxamer gel + H2O2' combination emerged as a promising chemical decontamination strategy for peri-implant diseases. It underlines the importance of tailoring treatment methods to the unique microbial challenges in peri-implant diseases and the necessity of combining chemical decontaminating strategies with established mechanical cleaning procedures for optimal management of peri-implant diseases.
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Antimicrobial resistance is a major threat to human health and must be approached from a One Health perspective. Use of antimicrobials in animal husbandry can lead to dissemination and persistence of resistance in human pathogens. Polyether ionophores (PIs) have antimicrobial activities and are among the most extensively used feed additives for major production animals. Recent discoveries of genetically encoded PI resistance mechanisms and co-localization of resistance mechanisms against PIs and antimicrobials used in human medicine on transferrable plasmids, have raised concerns that use of PIs as feed additives bear potential risks for human health. This review summarizes the current knowledge on PI resistance and discusses the potential consequences of PI-usage as feed additives in a One Health perspective.
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The recently discovered HEAT-like repeat (HLR) DNA glycosylase superfamily is widely distributed in all domains of life. The present bioinformatics and phylogenetic analysis shows that HLR DNA glycosylase superfamily members in the genus Bacillus form three subfamilies: AlkC, AlkD and AlkF/AlkG. The crystal structure of AlkF shows structural similarity with the DNA glycosylases AlkC and AlkD, however neither AlkF nor AlkG display any DNA glycosylase activity. Instead, both proteins have affinity to branched DNA structures such as three-way and Holliday junctions. A unique ß-hairpin in the AlkF/AlkG subfamily is most likely inserted into the DNA major groove, and could be a structural determinant regulating DNA substrate affinity. We conclude that AlkF and AlkG represent a new family of HLR proteins with affinity for branched DNA structures.
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Bacillus cereus/enzimología , Proteínas Bacterianas/química , ADN Glicosilasas/química , Sitios de Unión , Cromatografía Líquida de Alta Presión , Análisis por Conglomerados , Escherichia coli/genética , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Conformación de Ácido Nucleico , Estructura Terciaria de ProteínaRESUMEN
The Bacillus cereus type strain ATCC 14579 harbours pBClin15, a linear plasmid with similar genome organization to tectiviruses. Since phage morphogenesis is not known to occur it has been suggested that pBClin15 may be a defect relic of a tectiviral prophage without relevance for the bacterial physiology. However, in this paper, we demonstrate that a pBClin15-cured strain is more tolerant to antibiotics interfering with DNA integrity than the WT strain. Growth in the presence of crystal violet or the quinolones nalidixic acid, norfloxacin or ciprofloxacin resulted in aggregation and lysis of the WT strain, whereas the pBClin15-cured strain was unaffected. Microarray analysis comparing the gene expression in the WT and pBClin15-cured strains showed that pBClin15 gene expression was strongly upregulated in response to norfloxacin stress, and coincided with lysis and aggregation of the WT strain. The aggregating bacteria experienced a significant survival benefit compared with the planktonic counterparts in the presence of norfloxacin. There was no difference between the WT and pBClin15-cured strains during growth in the absence of norfloxacin, the pBClin15 genes were moderately expressed, and no effect was observed on chromosomal gene expression. These data demonstrate for the first time that although pBClin15 may be a remnant of a temperate phage, it negatively affects the DNA stress tolerance of B. cereus ATCC 14579. Furthermore, our results warrant a recommendation to always verify the presence of pBClin15 following genetic manipulation of B. cereus ATCC 14579.
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Bacillus cereus/efectos de los fármacos , Bacteriólisis , Adhesión Celular , ADN Bacteriano/metabolismo , Expresión Génica/efectos de los fármacos , Plásmidos , Quinolonas/metabolismo , Antibacterianos/metabolismo , Bacillus cereus/genética , Bacillus cereus/fisiología , Perfilación de la Expresión Génica , Análisis por Micromatrices , Transcripción GenéticaRESUMEN
Expression of rdar (red, dry, and rough) colony morphology-based biofilm formation in Escherichia coli is highly variable. To investigate the molecular mechanisms of semi-constitutive rdar morphotype formation, we compared their cyclic di-GMP turnover protein content and variability to the highly regulated, temperature-dependent morphotype of the historical and modern ST10 isolates E. coli MG1655 and Fec10, respectively. Subsequently, we assessed the effects of cyclic di-GMP turnover protein variants of the EAL phosphodiesterases YcgG and YjcC and the horizontally transferred diguanylate cyclase DgcX on biofilm formation and motility. The two YcgG variants with truncations of the N-terminal CSS signaling domain were oppositely effective in targeting downregulation of rdar biofilm formation compared to the full-length reference protein. Expression of the C-terminal truncated variants YjcCFec67 and YjcCTob1 showed highly diminished apparent phosphodiesterase activity compared to the reference YjcCMG1655. For YjcCFec101, substitution of the C-terminus led to an apparently inactive enzyme. Overexpression of the diguanylate cyclase DgcX contributed to upregulation of cellulose biosynthesis but not to elevated expression of the major biofilm regulator csgD in the "classical" rdar-expressing commensal strain E. coli Fec10. Thus, the c-di-GMP regulating network is highly complex with protein variants displaying substantially different apparent enzymatic activities.
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Experimental dental resin composites containing copper-doped mesoporous bioactive glass nanospheres (Cu-MBGN) were developed to impart anti-bacterial properties. Increasing amounts of Cu-MBGN (0, 1, 5 and 10 wt%) were added to the BisGMA/TEGDMA resin matrix containing micro- and nano-fillers of inert glass, keeping the resin/filler ratio constant. Surface micromorphology and elemental analysis were performed to evaluate the homogeneous distribution of filler particles. The study investigated the effects of Cu-MBGN on the degree of conversion, polymerization shrinkage, porosity, ion release and anti-bacterial activity on S. mutans and A. naeslundii. Experimental materials containing Cu-MBGN showed a dose-dependent Cu release with an initial burst and a further increase after 28 days. The composite containing 10% Cu-MBGN had the best anti-bacterial effect on S. mutans, as evidenced by the lowest adherence of free-floating bacteria and biofilm formation. In contrast, the 45S5-containing materials had the highest S. mutans adherence. Ca release was highest in the bioactive control containing 15% 45S5, which correlated with the highest number of open porosities on the surface. Polymerization shrinkage was similar for all tested materials, ranging from 3.8 to 4.2%, while the degree of conversion was lower for Cu-MBGN materials. Cu-MBGN composites showed better anti-bacterial properties than composites with 45S5 BG.
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Streptococcus mitis is a commensal bacterial species of the oral cavity, with the potential for opportunistic pathogenesis. For successful colonization, S. mitis must be able to adhere to surfaces of the oral cavity and survive and adapt to frequently changing environmental conditions. Cyclic-di-AMP (c-di-AMP) is a nucleotide second messenger, involved in the regulation of stress responses and biofilm formation in several bacterial species. Cyclic-di-AMP is produced by diadenylate cyclases and degraded by phosphodiesterases. We have previously shown that in S. mitis, one diadenylate cyclase (CdaA) and at least two phosphodiesterases (Pde1 and Pde2) regulate the intracellular concentration of c-di-AMP. In this study, we utilized S. mitis deletion mutants of cdaA, pde1, and pde2 to analyze the role of c-di-AMP signaling in various stress responses, biofilm formation, and adhesion to eukaryotic cells. Here, we demonstrate that the Δpde1 mutant displayed a tendency toward increased susceptibility to acetic acid at pH 4.0. Deletion of cdaA increases auto-aggregation of S. mitis but reduces biofilm formation on an abiotic surface. These phenotypes are more pronounced under acidic extracellular conditions. Inactivation of pde1 or pde2 reduced the tolerance to ciprofloxacin, and UV radiation and the Δpde1 mutant was more susceptible to Triton X-100, indicating a role for c-di-AMP signaling in responses to DNA damage and cell membrane perturbation. Finally, the Δpde2 mutant displayed a tendency toward a reduced ability to adhere to oral keratinocytes. Taken together, our results indicate an important role for c-di-AMP signaling in cellular processes important for colonization of the mouth.
Asunto(s)
Adaptación Fisiológica/fisiología , Adhesión Bacteriana/fisiología , Biopelículas/crecimiento & desarrollo , AMP Cíclico/metabolismo , Sistemas de Mensajero Secundario/fisiología , Streptococcus mitis/metabolismo , Ácido Acético/farmacología , Línea Celular Tumoral , Ciprofloxacina/farmacología , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 1/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 1/metabolismo , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 2/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 2/metabolismo , Eliminación de Gen , Regulación Bacteriana de la Expresión Génica/genética , Humanos , Queratinocitos/microbiología , Boca/microbiología , Octoxinol/farmacología , Liasas de Fósforo-Oxígeno/genética , Liasas de Fósforo-Oxígeno/metabolismo , Streptococcus mitis/crecimiento & desarrollo , Estrés Fisiológico/fisiologíaRESUMEN
Recognition of the fact that bacterial biofilm may play a role in the pathogenesis of disease has led to an increased focus on identifying diseases that may be biofilm-related. Biofilm infections are typically chronic in nature, as biofilm-residing bacteria can be resilient to both the immune system, antibiotics, and other treatments. This is a comprehensive review describing biofilm diseases in the auditory, the cardiovascular, the digestive, the integumentary, the reproductive, the respiratory, and the urinary system. In most cases reviewed, the biofilms were identified through various imaging technics, in addition to other study approaches. The current knowledge on how biofilm may contribute to the pathogenesis of disease indicates a number of different mechanisms. This spans from biofilm being a mere reservoir of pathogenic bacteria, to playing a more active role, e.g., by contributing to inflammation. Observations also indicate that biofilm does not exclusively occur extracellularly, but may also be formed inside living cells. Furthermore, the presence of biofilm may contribute to development of cancer. In conclusion, this review shows that biofilm is part of many, probably most chronic infections. This is important knowledge for development of effective treatment strategies for such infections.
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Polyether ionophores are antimicrobial compounds used as feed additives in poultry feed to control diseases caused by coccidia. In addition to the anticoccidial activity of these compounds, polyether ionophores also contain antibacterial properties. Resistance to the polyether ionophore narasin was recently shown to exist on mobile plasmids in Enterococcus faecium and the resistance mechanism was suggested to be associated with a two-gene operon encoding an ABC-type transporter. In this study we demonstrate that the genes encoding the putative narasin resistance mechanism confers reduced susceptibility to the polyether ionophores narasin, salinomycin and maduramicin, but not to monensin and suggest that this resistance mechanism should be referred to as NarAB. Importantly, NarAB does not affect the susceptibility of E. faecium to any of the tested antimicrobial compounds that are used in clinical medicine. However, we show that conjugation in the presence of certain polyether ionophores increases the number of vancomycin resistant E. faecium suggesting that narasin and certain other polyether ionophores can contribute to the persistence of VRE in poultry populations.
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Quinolones are important antimicrobials for both humans and animals, and resistance toward these compounds is a serious threat to public health. In Norway, quinolone resistant E. coli (QREC) have been detected at low levels in a high proportion of broiler flocks, even without the use of quinolones in rearing of broilers. Due to the pyramidal structure of broiler breeding, QREC isolates may be disseminated from grandparent animals down through the pyramid. However, quinolone resistance can also develop in wild type E. coli through specific chromosomal mutations, and by horizontal acquisition of plasmid-mediated quinolone resistance genes. The goal of this study was to determine whether QREC is disseminated through the broiler breeding pyramid or developed locally at some stage in the broiler production chain. For this purpose, we whole genome sequenced wild type- and QREC isolates from broiler and parent flocks that had been isolated in the Norwegian monitoring program for antimicrobial resistance in feed, food and animals (NORM-VET) between 2006 and 2017, from 22 different production sites. The sequencing data was used for typing of the isolates, phylogenetic analysis and identification of relevant resistance mechanisms. Highly similar QREC isolates were identified within major sequence types from multiple production sites, suggesting dissemination of QREC isolates in the broiler production chain. The occurrence of potential resistance development among the WT E. coli was low, indicating that this may be a rare phenomenon in the Norwegian broiler production. The results indicate that the majority of the observed QREC at the bottom of the broiler production pyramid originates from parent or grandparent animals. These results highlight the importance of surveillance at all levels of the broiler production pyramid and of implementation of proper biosecurity measures to control dissemination of QREC.