scholarly journals Aggregatibacter actinomycetemcomitans- A periodontopathogen

2021 ◽  
Vol 6 (2) ◽  
pp. 61-67
Author(s):  
Ashwath B ◽  
Adline Vadhana D ◽  
Anitha V ◽  
Shanmugam M
Keyword(s):  
Oral Cavity ◽  
Virulence Factors ◽  
Severe Form ◽  
Cytolethal Distending Toxin ◽  
Immunosuppressive Activity ◽  
Gram Negative ◽  
Recent Developments ◽  
Periodontal Destruction ◽  
Virulence Target ◽  
Systemic Antibiotics

is a gram-negative oral pathobiont that is associated with severe form of periodontitis. This bacterium has various virulence factors which enables the bacterium to colonize the oral cavity, invade and evade the host defences. Leukotoxin and cytolethal distending toxin are the important virulence factors that causes periodontal destruction. Periodontal infections with seems to be refractory to conventional therapy and systemic antibiotics. Hence, leukotoxin represents an ideal anti-virulence target and inhibition of its immunosuppressive activity would eliminate the colonization advantage provided to the bacteria by the toxin. This review provides a comprehensive update of with an emphasis on its virulence factors leukotoxin and cytolethal distending toxin and its role in periodontal destruction and recent developments in the management.

scholarly journals Clonal Clusters, Molecular Resistance Mechanisms and Virulence Factors of Gram-Negative Bacteria Isolated from Chronic Wounds in Ghana

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 339
Author(s):  
Denise Dekker ◽  
Frederik Pankok ◽  
Thorsten Thye ◽  
Stefan Taudien ◽  
Kwabena Oppong ◽  
...  
Keyword(s):  
Molecular Epidemiology ◽  
Virulence Factors ◽  
Iron Uptake ◽  
Chronic Wounds ◽  
Sub Saharan Africa ◽  
Gram Negative Bacteria ◽  
Beta Lactamase ◽  
Secretion Systems ◽  
Gram Negative ◽  
E Coli

Wound infections are common medical problems in sub-Saharan Africa but data on the molecular epidemiology are rare. Within this study we assessed the clonal lineages, resistance genes and virulence factors of Gram-negative bacteria isolated from Ghanaian patients with chronic wounds. From a previous study, 49 Pseudomonas aeruginosa, 21 Klebsiellapneumoniae complex members and 12 Escherichia coli were subjected to whole genome sequencing. Sequence analysis indicated high clonal diversity with only nine P. aeruginosa clusters comprising two strains each and one E. coli cluster comprising three strains with high phylogenetic relationship suggesting nosocomial transmission. Acquired beta-lactamase genes were observed in some isolates next to a broad spectrum of additional genetic resistance determinants. Phenotypical expression of extended-spectrum beta-lactamase activity in the Enterobacterales was associated with blaCTX-M-15 genes, which are frequent in Ghana. Frequently recorded virulence genes comprised genes related to invasion and iron-uptake in E. coli, genes related to adherence, iron-uptake, secretion systems and antiphagocytosis in P. aeruginosa and genes related to adherence, biofilm formation, immune evasion, iron-uptake and secretion systems in K. pneumonia complex. In summary, the study provides a piece in the puzzle of the molecular epidemiology of Gram-negative bacteria in chronic wounds in rural Ghana.

scholarly journals Folding Control in the Path of Type 5 Secretion

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 341
Author(s):  
Nathalie Dautin
Keyword(s):  
Protein Folding ◽  
Virulence Factors ◽  
Secretion System ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Final Destination ◽  
Cell Compartments ◽  
Recent Addition ◽  
Functionally Diverse

The type 5 secretion system (T5SS) is one of the more widespread secretion systems in Gram-negative bacteria. Proteins secreted by the T5SS are functionally diverse (toxins, adhesins, enzymes) and include numerous virulence factors. Mechanistically, the T5SS has long been considered the simplest of secretion systems, due to the paucity of proteins required for its functioning. Still, despite more than two decades of study, the exact process by which T5SS substrates attain their final destination and correct conformation is not totally deciphered. Moreover, the recent addition of new sub-families to the T5SS raises additional questions about this secretion mechanism. Central to the understanding of type 5 secretion is the question of protein folding, which needs to be carefully controlled in each of the bacterial cell compartments these proteins cross. Here, the biogenesis of proteins secreted by the Type 5 secretion system is discussed, with a focus on the various factors preventing or promoting protein folding during biogenesis.

scholarly journals Systemic Antibiotics and Obesity: Analyses from a Population-Based Cohort

2021 ◽  
Vol 10 (12) ◽  
pp. 2601
Author(s):  
So Young Park ◽  
Morena Ustulin ◽  
SangHyun Park ◽  
Kyung-Do Han ◽  
Joo Young Kim ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Adult Population ◽  
Antibiotic Use ◽  
Population Based ◽  
Obesity Risk ◽  
Gram Negative ◽  
Korean Adult ◽  
Korean National Health Insurance ◽  
Gram Negative Organisms ◽  
Systemic Antibiotics

Background: In this study, we analyzed the association between antibiotic use and obesity and metabolic syndrome (MS) in a Korean adult population. Methods: Subjects using the Korean National Health Insurance Service sample cohort were retrospectively analyzed in 2015. The differences in obesity and metabolic syndrome (MS) status were compared and analyzed according to duration of systemic antibiotic treatment in the previous 10 years (non-users, 1st, 2nd, and 3rd tertile). Results: Subjects who used systemic antibiotics for longer periods were older, satisfied more criteria for MS, and had more comorbidities than non-users (non-users vs. 3rd tertile, p < 0.0001 for all). After adjusting for confounding factors, the risk of obesity was higher in subjects who used systemic antibiotics for longer periods than in non-users (non-users vs. 3rd tertile, OR (odds ratio) (95% CI (confidence interval)); 1.20 (1.12–1.38)). The criteria for MS were more satisfied in the 3rd tertile than in non-users. A higher obesity risk was also found in subjects treated with antibiotics targeting Gram-negative organisms than in those targeting Gram-positive organisms. Conclusion: The risk of obesity was higher in subjects who took systemic antibiotics more frequently. The risk was more prominent when they took antibiotics targeting Gram-negative bacteria.

scholarly journals Regulation of Plant Mineral Nutrition by Signal Molecules

2021 ◽  
Vol 9 (4) ◽  
pp. 774
Author(s):  
Vipin Chandra Kalia ◽  
Chunjie Gong ◽  
Sanjay K. S. Patel ◽  
Jung-Kul Lee
Keyword(s):  
Signal Molecules ◽  
Gram Negative Bacteria ◽  
Human Beings ◽  
High Cell ◽  
Specific Chemical ◽  
Gram Negative ◽  
Plant Mineral Nutrition ◽  
Recent Developments ◽  
Cell Densities ◽  
Metabolic Activities

Microbes operate their metabolic activities at a unicellular level. However, it has been revealed that a few metabolic activities only prove beneficial to microbes if operated at high cell densities. These cell density-dependent activities termed quorum sensing (QS) operate through specific chemical signals. In Gram-negative bacteria, the most widely reported QS signals are acylhomoserine lactones. In contrast, a novel QS-like system has been elucidated, regulating communication between microbes and plants through strigolactones. These systems regulate bioprocesses, which affect the health of plants, animals, and human beings. This mini-review presents recent developments in the QS and QS-like signal molecules in promoting plant health.

scholarly journals Helicobacter pylori colonization and oral health in children

2017 ◽  
Vol 12 (2) ◽  
pp. 41-44
Author(s):  
Vasile Valeriu LUPU ◽  
◽  
Gabriela PĂDURARU ◽  
Anca ADAM ◽  
Ana-Maria DĂBULEANU ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Oral Health ◽  
Gastric Mucosa ◽  
Oral Cavity ◽  
Gold Standard ◽  
Dental Plaque ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Standard Triple Therapy ◽  
H Pylori

Helicobacter pylori (H. pylori) is a microaerophilic gram-negative bacterium infecting approximately one half of the world’s population. The oral cavity and dental plaque may be a reservoir for H. pylori infection. Diagnosis of H. pylori infection in children differs from that of adults. Although H. pylori has long been known to be detected in the oral cavity, the significance of such findings are controversial. Oral H. pylori may play an important role in re-infection of the gastric mucosa. The gold standard for eradicating H. pylori infection is standard triple therapy. The studies have shown promising results in the management of both oral and gastric H. pylori.

scholarly journals Autotransporter secretion exploits the bacterial actin-homologue

2018 ◽  
Author(s):  
Mahmoud M. Ashawesh ◽  
Robert Markus ◽  
Christopher N. Penfold ◽  
Kim R. Hardie
Keyword(s):  
Bacterial Infection ◽  
Virulence Factors ◽  
Pathogenic Bacteria ◽  
Super Resolution ◽  
Resistance Mechanisms ◽  
Dynamic Interaction ◽  
Bacterial Toxins ◽  
Gram Negative ◽  
Bacterial Cytoskeleton ◽  
Development Of Resistance

AbstractBacterial infection of humans, animals and plants relies heavily on secreted proteases that degrade host defences or activate bacterial toxins. The largest family of proteins secreted by Gram-negative pathogenic bacteria, the Autotransporters (ATs), includes key proteolytic virulence factors. There remains uncertainty about the mechanistic steps of the pathway ATs share to exit bacteria, and how it is energetically driven. This study set out to shed light on the AT secretion pathway with the ultimate aim of uncovering novel antimicrobial targets that would be unlikely to trigger the development of resistance mechanisms in bacteria. To do this, two AT virulence factors with distinct proteolytic functions, EspC (secreted from EnteropathogenicEscherichia coli) and AaaA (tethered to the extracellular surface ofPseudomonas aeruginosa) were chosen. EspC and AaaA were fluorescently labelled using two separate methods to establish the localization patterns of ATs as they are secreted from a bacterial cell. Super resolution microscopy revealed that localization of ATs occurs via a helical route along the bacterial cytoskeleton. In addition to requiring the conserved C-terminal β-barrel translocator domain of the AT, we present the first evidence that secretion is dependent on a dynamic interaction with a structure reliant upon the actin homologue MreB and the Sec translocon. These findings provide a step forward in the mechanistic understanding of the secretion of this widely distributed family of proteins that have pivotal roles in bacterial pathogenesis and conserved structural properties that could serve as novel broad-range antimicrobial targets.SignificanceSecreted bacterial proteases facilitate the infection of human, animal and plant hosts by degrading host defences or activating bacterial toxins. The autotransporter family is the largest family of proteins secreted from Gram-negative bacteria, and includes proteolytic virulence factors crucial to bacterial infection. Precisely how autotransporters migrate from the inside to the outside of the cell, and how this movement is energetically driven is a mystery. We demonstrate a spiral pathway of autotransporter secretion, presenting evidence that it involves a dynamic interaction with the actin homologue MreB that comprises the bacterial cytoskeleton. Our findings open the way to unravelling the mechanism of autotransporter secretion and offer the possibility to identify novel antimicrobial targets unlikely to trigger the development of antimicrobial resistance.

scholarly journals Comparison of Virulence Factors of Different Candida Species Isolated from the Oral Cavity of Cancer Patients and Normal Individuals

2019 ◽  
Vol In Press (In Press) ◽  
Author(s):  
Mehrnoush Maheronnaghsh ◽  
Mahnaz Fatahinia ◽  
Parvin Dehghan ◽  
Ali Zarei Mahmoudabadi ◽  
Mahnaz Kheirkhah
Keyword(s):  
Oral Cavity ◽  
Cancer Patients ◽  
Virulence Factors ◽  
Candida Species ◽  
Normal Individuals

scholarly journals Aggregatibacter actinomycetemcomitans: The virulence factors and relation to persistence biofilm formation

Biomedicine ◽  
2021 ◽  
Vol 40 (4) ◽  
pp. 429-435
Author(s):  
Syakir Syahiran ◽  
Wan Rohani Wan Taib ◽  
Norzawani Jaffar
Keyword(s):  
Oral Cavity ◽  
Virulence Factors ◽  
Tooth Loss ◽  
Periodontal Diseases ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Aggressive Periodontitis ◽  
Essential Factor ◽  
Abiotic Surfaces ◽  
Functional Biology ◽  
Systemic Infections

Periodontitis is an infectious and inflammatory condition that is associated with subgingival biofilms in tooth-supporting tissues. Among the several hundred isolated organisms in the oral cavity, one of the most isolated bacteria from infected periodontal pockets are Aggregatibacter actinomycetemcomitans. It is a Gram-negative, facultative anaerobic bacillus that causes juvenile (localized aggressive periodontitis) and adolescent periodontal diseases. The development of biofilms is an essential factor in pathogenesis for A. actinomycetemcomitans. The early attachment of A. actinomycetemcomitans to abiotic surfaces relies on its protein-like fimbriae. This organism's ability to form tenacious biofilms can determine its survival and progression. A. actinomycetemcomitans, a pathogen not solely in periodontal but also involve in some systemic infections. This species has several virulence factors and genes that contribute to its oral cavity survival and, worst of all, cause bone resorption and tooth loss. Genetic diversity between the different A. actinomycetemcomitans isolates are great, and their ability to express and release virulence factors varies. In this review article, we discuss about the potential virulence factors and candidates genes for A. actinomycetemcomitans and their roles within periodontal disease by revealing their functional biology in facilitating attachment to oral surfaces, hindering protection of the host and causing inflammation and degradation of tissue.

scholarly journals The Pseudomonas syringae avrRpt2 Gene Contributes to Virulence on Tomato

2005 ◽  
Vol 18 (7) ◽  
pp. 626-633 ◽  
Author(s):  
Melisa T. S. Lim ◽  
Barbara N. Kunkel
Keyword(s):  
Pseudomonas Syringae ◽  
Virulence Factors ◽  
Host Defense ◽  
Virulence Gene ◽  
Bacterial Virulence ◽  
Host Tissue ◽  
Native Strain ◽  
Phytopathogenic Bacteria ◽  
Gram Negative ◽  
Mutant Derivative

In order to cause disease on plants, gram-negative phytopathogenic bacteria introduce numerous virulence factors into the host cell in order to render host tissue more hospitable for pathogen proliferation. The mode of action of such bacterial virulence factors and their interaction with host defense pathways remain poorly understood. avrRpt2, a gene from Pseudomonas syringae pv. tomato JL1065, has been shown to promote the virulence of heterologous P. syringae strains on Arabidopsis thaliana. However, the contribution of avrRpt2 to the virulence of JL1065 has not been examined previously. We show that a mutant derivative of JL1065 that carries a disruption in avrRpt2 is impaired in its ability to cause disease on tomato (Lycopersicon esculentum), indicating that avrRpt2 also acts as a virulence gene in its native strain on a natural host. The virulence activity of avrRpt2 was detectable on tomato lines that are defective in either ethylene perception or the accumulation of salicylic acid, but could not be detected on a tomato mutant insensitive to jasmonic acid. The enhanced virulence conferred by the expression of avrRpt2 in JL1065 was not associated with the suppression of several defense-related genes induced during the infection of tomato.

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