scholarly journals Salmonella Extracellular Polymeric Substances Modulate Innate Phagocyte Activity and Enhance Tolerance of Biofilm-Associated Bacteria to Oxidative Stress

2020 ◽  
Vol 8 (2) ◽  
pp. 253 ◽  
Author(s):  
Mark M. Hahn ◽  
John S. Gunn
Keyword(s):  
Extracellular Polymeric Substances ◽  
Capsular Polysaccharides ◽  
Chronic Infections ◽  
Associated Bacteria ◽  
Cholesterol Gallstones ◽  
Colanic Acid ◽  
Phagocyte Activity ◽  
Pathogen Clearance ◽  
Vi Antigen

Salmonella enterica serovar Typhi causes 14.3 million acute cases of typhoid fever that are responsible for 136,000 deaths each year. Chronic infections occur in 3%–5% of those infected and S. Typhi persists primarily in the gallbladder by forming biofilms on cholesterol gallstones, but how these bacterial communities evade host immunity is not known. Salmonella biofilms produce several extracellular polymeric substances (EPSs) during chronic infection, which are hypothesized to prevent pathogen clearance either by protecting biofilm-associated bacteria from direct humoral attack or by modulating innate phagocyte interaction with biofilms. Using wild-type and EPS-deficient planktonic and biofilm Salmonella, the direct attack hypothesis was tested by challenging biofilms with human serum and antimicrobial peptides. Biofilms were found to be tolerant to these molecules, but these phenotypes were independent of the tested EPSs. By examining macrophage and neutrophil responses, new roles for biofilm-associated capsular polysaccharides and slime polysaccharides were identified. The S. Typhi Vi antigen was found to modulate innate immunity by reducing macrophage nitric oxide production and neutrophil reactive oxygen species (ROS) production. The slime polysaccharides colanic acid and cellulose were found to be immune-stimulating and represent a key difference between non-typhoidal serovars and typhoidal serovars, which do not express colanic acid. Furthermore, biofilm tolerance to the exogenously-supplied ROS intermediates hydrogen peroxide (H2O2) and hypochlorite (ClO−) indicated an additional role of the capsular polysaccharides for both serovars in recalcitrance to H2O2 but not ClO−, providing new understanding of the stalemate that arises during chronic infections and offering new directions for mechanistic and clinical studies.

The Abundance and Organization of Salmonella Extracellular Polymeric Substances in Gallbladder-Mimicking Environments and In Vivo

2021 ◽  
Author(s):  
Mark M. Hahn ◽  
Juan F. González ◽  
Regan Hitt ◽  
Lauren Tucker ◽  
John S. Gunn
Keyword(s):  
Spatial Organization ◽  
Extracellular Polymeric Substances ◽  
Wild Type ◽  
Chronic Infections ◽  
Human Bile ◽  
Cholesterol Gallstones ◽  
Coated Surfaces ◽  
Biofilm Development

Salmonella enterica serovar Typhi ( S. Typhi ) causes chronic infections by establishing biofilms on cholesterol gallstones. Production of extracellular polymeric substances (EPSs) is key to biofilm development and biofilm architecture depends on which EPSs are made. The presence and spatial distribution of Salmonella EPSs produced in vitro and in vivo were investigated in S. Typhi murium and S. Typhi biofilms by confocal microscopy. Comparisons between serovars and EPS-mutant bacteria were examined by growth on cholesterol-coated surfaces, with human gallstones in ox or human bile, and in mice with gallstones. On cholesterol-coated surfaces, major differences in EPS biomass were not found between serovars. Co-culture biofilms containing wild-type (WT) and EPS-mutant bacteria demonstrated WT compensation for EPS mutations. Biofilm EPS analysis from gallbladder-mimicking conditions found that culture in human bile more consistently replicated the relative abundance and spatial organization of each EPS on gallstones from the chronic mouse model than culture in ox bile. S. Typhi murium biofilms cultured in vitro on gallstones in ox bile exhibited co-localized pairings of curli fimbriae/lipopolysaccharide and O antigen capsule/cellulose while these associations were not present in S. Typhi biofilms or in mouse gallstone biofilms. In general, inclusion of human bile with gallstones in vitro replicated biofilm development on gallstones in vivo , demonstrating its strength as a model for studying biofilm parameters or EPS-directed therapeutic treatments.

Role of Cellulose and Colanic Acid in Attachment of Shiga Toxin–Producing Escherichia coli to Lettuce and Spinach in Different Water Hardness Environments

2015 ◽  
Vol 78 (8) ◽  
pp. 1461-1466 ◽  
Author(s):  
CHI-CHING LEE ◽  
JINRU CHEN ◽  
JOSEPH F. FRANK
Keyword(s):  
Escherichia Coli ◽  
Surface Charge ◽  
Shiga Toxin ◽  
Extracellular Polymeric Substances ◽  
Water Hardness ◽  
Wild Type ◽  
Cut Edge ◽  
Colanic Acid ◽  
Spinach Leaf

This study investigated the role of extracellular cellulose production by Shiga toxin–producing Escherichia coli (STEC) on attachment to lettuce and spinach in different water hardness environments. Two cellulose-producing wild-type STEC strains, 19 (O5:H−) and 49 (O103:H2), and their cellulose-deficient derivatives were used. Strain 49 also produced colanic acid as a constituent of its extracellular polymeric substances. Attached cells were determined by plate counts on the surface and cut edge of the leaves after an attachment period of 2 h at 4°C. Hydrophobicity and surface charge of the cells were determined. Strain 49 attached at levels 0.3 and 0.6 log greater to the surface and 0.9 and 0.4 log greater to the cut edges of spinach compared to strain 19 for both wild-type and cellulose-deficient cells (P > 0.05). Cellulose-producing cells attached more to the surface of lettuce but not of spinach than did cellulose-deficient cells. However, more cellulose-deficient cells attached (at levels 0.66 and 0.3 log greater) to the cut edge of lettuce (representing damaged tissue) than did cellulose-proficient cells (P > 0.05). Colanic acid production was associated with cell surfaces of low hydrophobicity. There was a decreasing level of attachment for the colanic acid–producing strain when water hardness increased from 200 to 1,000 pm on lettuce and spinach leaf surfaces, but no effects were seen for other cells. This decreased attachment was associated with a more negative surface charge. Cells that produced colanic acid were less hydrophobic and exhibited greater attachment to the surface and cut edge of spinach when compared to cells that did not produce colanic acid. Attachment of colanic acid–producing cells to leafy green surfaces was enhanced in higher water hardness environments. These data indicate that attachment of E. coli O157:H7 to leafy greens involves multiple mechanisms that are influenced by the type of leafy green, damage to the leaf, and the water hardness environment.

scholarly journals The Role of Bacterial Biofilm in Antibiotic Resistance and Food Contamination

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Gedif Meseret Abebe
Keyword(s):  
Antibiotic Resistance ◽  
Food Processing ◽  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Food Contamination ◽  
Bacterial Biofilm ◽  
Natural Environments ◽  
Chronic Infections ◽  
Related Factors

Biofilm is a microbial association or community attached to different biotic or abiotic surfaces or environments. These surface-attached microbial communities can be found in food, medical, industrial, and natural environments. Biofilm is a critical problem in the medical sector since it is formed on medical implants within human tissue and involved in a multitude of serious chronic infections. Food and food processing surface become an ideal environment for biofilm formation where there are sufficient nutrients for microbial growth and attachment. Therefore, biofilm formation on these surfaces, especially on food processing surface becomes a challenge in food safety and human health. Microorganisms within a biofilm are encased within a matrix of extracellular polymeric substances that can act as a barrier and recalcitrant for different hostile conditions such as sanitizers, antibiotics, and other hygienic conditions. Generally, they persist and exist in food processing environments where they become a source of cross-contamination and foodborne diseases. The other critical issue with biofilm formation is their antibiotic resistance which makes medication difficult, and they use different physical, physiological, and gene-related factors to develop their resistance mechanisms. In order to mitigate their production and develop controlling methods, it is better to understand growth requirements and mechanisms. Therefore, the aim of this review article is to provide an overview of the role of bacterial biofilms in antibiotic resistance and food contamination and emphasizes ways for controlling its production.

scholarly journals Helicobacter pyloriBiofilm Formation and Its Potential Role in Pathogenesis

2018 ◽  
Vol 82 (2) ◽  
Author(s):  
Skander Hathroubi ◽  
Stephanie L. Servetas ◽  
Ian Windham ◽  
D. Scott Merrell ◽  
Karen M. Ottemann
Keyword(s):  
Extracellular Polymeric Substances ◽  
Antimicrobial Treatment ◽  
Gastric Ulcers ◽  
Chronic Infections ◽  
Content Type ◽  
Mucosal Layer ◽  
Urease Production ◽  
H Pylori ◽  
Biofilm Structure

SUMMARYDespite decades of effort,Helicobacter pyloriinfections remain difficult to treat. Over half of the world's population is infected byH. pylori, which is a major cause of duodenal and gastric ulcers as well as gastric cancer. During chronic infection,H. pylorilocalizes within the gastric mucosal layer, including deep within invaginations called glands; thanks to its impressive ability to survive despite the harsh acidic environment, it can persist for the host's lifetime. This ability to survive and persist in the stomach is associated with urease production, chemotactic motility, and the ability to adapt to the fluctuating environment. Additionally, biofilm formation has recently been suggested to play a role in colonization. Biofilms are surface-associated communities of bacteria that are embedded in a hydrated matrix of extracellular polymeric substances. Biofilms pose a substantial health risk and are key contributors to many chronic and recurrent infections. This link between biofilm-associated bacteria and chronic infections likely results from an increased tolerance to conventional antibiotic treatments as well as immune system action. The role of this biofilm mode in antimicrobial treatment failure andH. pylorisurvival has yet to be determined. Furthermore, relatively little is known about theH. pyloribiofilm structure or the genes associated with this mode of growth. In this review, therefore, we aim to highlight recent findings concerningH. pyloribiofilms and the molecular mechanism of their formation. Additionally, we discuss the potential roles of biofilms in the failure of antibiotic treatment and in infection recurrence.

scholarly journals Salmonella Biofilms Tolerate Hydrogen Peroxide by a Combination of Extracellular Polymeric Substance Barrier Function and Catalase Enzymes

2021 ◽  
Vol 11 ◽  
Author(s):  
Mark M. Hahn ◽  
Juan F. González ◽  
John S. Gunn
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Extracellular Polymeric Substances ◽  
Biofilm Growth ◽  
Community Function ◽  
O Antigen ◽  
Colanic Acid ◽  
Oxidative Resistance ◽  
The Individual ◽  
Vi Antigen

The ability of Salmonella enterica subspecies enterica serovar Typhi (S. Typhi) to cause chronic gallbladder infections is dependent on biofilm growth on cholesterol gallstones. Non-typhoidal Salmonella (e.g. S. Typhimurium) also utilize the biofilm state to persist in the host and the environment. How the pathogen maintains recalcitrance to the host response, and oxidative stress in particular, during chronic infection is poorly understood. Previous experiments demonstrated that S. Typhi and S. Typhimurium biofilms are tolerant to hydrogen peroxide (H2O2), but that mutations in the biofilm extracellular polymeric substances (EPSs) O antigen capsule, colanic acid, or Vi antigen reduce tolerance. Here, biofilm-mediated tolerance to oxidative stress was investigated using a combination of EPS and catalase mutants, as catalases are important detoxifiers of H2O2. Using co-cultured biofilms of wild-type (WT) bacteria with EPS mutants, it was demonstrated that colanic acid in S. Typhimurium and Vi antigen in S. Typhi have a community function and protect all biofilm-resident bacteria rather than to only protect the individual cells producing the EPSs. However, the H2O2 tolerance deficiency of a O antigen capsule mutant was unable to be compensated for by co-culture with WT bacteria. For curli fimbriae, both WT and mutant strains are tolerant to H2O2 though unexpectedly, co-cultured WT/mutant biofilms challenged with H2O2 resulted in sensitization of both strains, suggesting a more nuanced oxidative resistance alteration in these co-cultures. Three catalase mutant (katE, katG and a putative catalase) biofilms were also examined, demonstrating significant reductions in biofilm H2O2 tolerance for the katE and katG mutants. Biofilm co-culture experiments demonstrated that catalases exhibit a community function. We further hypothesized that biofilms are tolerant to H2O2 because the physical barrier formed by EPSs slows penetration of H2O2 into the biofilm to a rate that can be mitigated by intra-biofilm catalases. Compared to WT, EPS-deficient biofilms have a heighted response even to low-dose (2.5 mM) H2O2 challenge, confirming that resident bacteria of EPS-deficient biofilms are under greater stress and have limited protection from H2O2. Thus, these data provide an explanation for how Salmonella achieves tolerance to H2O2 by a combination of an EPS-mediated barrier and enzymatic detoxification.

scholarly journals The MarR-Type Regulator PA3458 Is Involved in Osmoadaptation Control in Pseudomonas aeruginosa

2021 ◽  
Vol 22 (8) ◽  
pp. 3982
Author(s):  
Karolina Kotecka ◽  
Adam Kawalek ◽  
Kamil Kobylecki ◽  
Aneta Agnieszka Bartosik
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Binding Sites ◽  
Transcriptional Profiling ◽  
Mrna Level ◽  
Transcriptional Regulators ◽  
Resistance Mechanisms ◽  
Chronic Infections ◽  
Environmental Signals ◽  
Regulatory Systems

Pseudomonas aeruginosa is a facultative human pathogen, causing acute and chronic infections that are especially dangerous for immunocompromised patients. The eradication of P. aeruginosa is difficult due to its intrinsic antibiotic resistance mechanisms, high adaptability, and genetic plasticity. The bacterium possesses multilevel regulatory systems engaging a huge repertoire of transcriptional regulators (TRs). Among these, the MarR family encompasses a number of proteins, mainly acting as repressors, which are involved in response to various environmental signals. In this work, we aimed to decipher the role of PA3458, a putative MarR-type TR from P. aeruginosa. Transcriptional profiling of P. aeruginosa PAO1161 overexpressing PA3458 showed changes in the mRNA level of 133 genes; among them, 100 were down-regulated, suggesting the repressor function of PA3458. Concomitantly, ChIP-seq analysis identified more than 300 PA3458 binding sites in P. aeruginosa. The PA3458 regulon encompasses genes involved in stress response, including the PA3459–PA3461 operon, which is divergent to PA3458. This operon encodes an asparagine synthase, a GNAT-family acetyltransferase, and a glutamyl aminopeptidase engaged in the production of N-acetylglutaminylglutamine amide (NAGGN), which is a potent bacterial osmoprotectant. We showed that PA3458-mediated control of PA3459–PA3461 expression is required for the adaptation of P. aeruginosa growth in high osmolarity. Overall, our data indicate that PA3458 plays a role in osmoadaptation control in P. aeruginosa.

scholarly journals Characterization of symbiotic and associated bacteria from entomopathogenic nematode Heterorhabditis sp. (nematode: Heterorhabditidae) isolated from India

2020 ◽  
Vol 30 (1) ◽  
Author(s):  
Rashid Pervez ◽  
Showkat Ahmad Lone ◽  
Sasmita Pattnaik
Keyword(s):  
Insect Pests ◽  
Entomopathogenic Nematode ◽  
Alcaligenes Faecalis ◽  
Symbiotic Bacteria ◽  
Rrna Gene ◽  
Main Body ◽  
Associated Bacteria ◽  
Molecular Approaches

Abstract Background Entomopathogenic nematodes (EPNs) harboring symbiotic bacteria are one of the safest alternatives to the chemical insecticides for the control of various insect pests. Infective juveniles of EPNs locate a target insect, enter through the openings, and reach the hemocoel, where they release the symbiotic bacteria and the target gets killed by the virulence factors of the bacteria. Photorhabdus with Heterorhabditis spp. are well documented; little is known about the associated bacteria. Main body In this study, we explored the presence of symbiotic and associated bacteria from Heterorhabditis sp. (IISR-EPN 09) and characterized by phenotypic, biochemical, and molecular approaches. Six bacterial isolates, belonging to four different genera, were recovered and identified as follows: Photorhabdus luminescens, one each strain of Providencia vermicola, Pseudomonas entomophila, Alcaligenes aquatilis, and two strains of Alcaligenes faecalis based on the phenotypic, biochemical criteria and the sequencing of 16S rRNA gene. Conclusion P. luminescens is symbiotically associated with Heterorhabditis sp. (IISR-EPN 09), whereas P. vermicola, P. entomophila, A. aquatilis, and A. faecalis are the associated bacteria. Further studies are needed to determine the exact role of the bacterial associates with the Heterorhabditis sp.

scholarly journals Obesity-Induced Dysbiosis Exacerbates IFN-γ Production and Pulmonary Inflammation in the Mycobacterium tuberculosis Infection

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1732
Author(s):  
Sandra Patricia Palma Albornoz ◽  
Thais Fernanda de Campos Fraga-Silva ◽  
Ana Flávia Gembre ◽  
Rômulo Silva de Oliveira ◽  
Fernanda Mesquita de Souza ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Gut Microbiota ◽  
Inflammatory Diseases ◽  
Pulmonary Inflammation ◽  
Host Susceptibility ◽  
Chronic Infections ◽  
Mycobacterium Tuberculosis Infection ◽  
Pulmonary Damage ◽  
Ifn Γ

The microbiota of the gut–lung axis affects local and far-reaching immune responses and might also trigger chronic and inflammatory diseases. We hypothesized that gut dysbiosis induced by obesity, which coexists in countries with a high tuberculosis burden, aggravates the host susceptibility and the pulmonary damage tolerance. To assess our hypothesis, we used a model of high-fat diet (HFD)-induced obesity, followed by infection of C57BL/6 mice with Mycobacterium tuberculosis. We showed that obesity increased the susceptibility, the pulmonary inflammation and IFN-γ levels in M. tuberculosis-infected mice. During the comorbidity obesity and tuberculosis, there is an increase of Bacteroidetes and Firmicutes in the lungs, and an increase of Firmicutes and butyrate in the feces. Depletion of gut microbiota by antibiotic treatment in the obese infected mice reduced the frequencies of CD4+IFN-γ+IL-17− cells and IFN-γ levels in the lungs, associated with an increase of Lactobacillus. Our findings reinforce the role of the gut–lung axis in chronic infections and suggest that the gut microbiota modulation may be a potential host-directed therapy as an adjuvant to treat TB in the context of IFN-γ-mediated immunopathology.

Bacterial biofilm adherence to middle-ear ventilation tubes: scanning electron micrograph images and literature review

2007 ◽  
Vol 121 (10) ◽  
pp. 993-997 ◽  
Author(s):  
M Barakate ◽  
E Beckenham ◽  
J Curotta ◽  
M da Cruz
Keyword(s):  
Middle Ear ◽  
Bacterial Biofilm ◽  
Electron Micrograph ◽  
Ventilation Tube ◽  
Scanning Electron Micrograph ◽  
Chronic Infections ◽  
Middle Ear Ventilation ◽  
Conventional Antibiotics ◽  
Scanning Electron

Introduction: The organisms that cause many device-related and other chronic infections actually grow in biofilms in or on these devices. We sought to examine the role of biofilm formation in chronic middle-ear ventilation tube infection.Case report: Scanning electron micrograph images are presented which demonstrate biofilm on a middle-ear ventilation tube removed from a five-year-old child's chronically discharging ear. A review of the relevant international literature explores the role of biofilms in chronic infection and discusses potential intervention strategies.Conclusion: Biofilms may be responsible for chronic middle-ear ventilation tube infection that resists treatment with conventional antibiotics.

Sign in / Sign up

Export Citation Format

Share Document