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Identification And Characterization Of Farr And Fare As A Regulator And Effector Of Fatty Acid Resistance In Staphylococcus Aureus, Heba Alnaseri

Electronic Thesis and Dissertation Repository

Although Staphylococcus aureus is exposed to antimicrobial fatty acids on the skin, in nasal secretions and in abscesses, specific mechanisms for regulating gene expression and intrinsic resistance in response to these fatty acids have not been reported. Through in vitro selection for increased resistance of S. aureus to linoleic acid, I identified fatty acid resistant clone FAR7, where a single nucleotide polymorphism caused a His₁₂₁Tyr substitution in an uncharacterized member of the TetR family of transcriptional regulators, which is divergently transcribed from a gene encoding a member of the resistance-nodulation-division superfamily of multi-drug efflux pumps. I named these …

Mechanism Of Candida Albicans Biofilm And Virulence Inhibition By A Bacterial Secreted Factor, Carrie Graham

Dissertations & Theses (Open Access)

The human microbiome is a diverse polymicrobial population comprised of both fungi and bacteria. Perturbations of the normal microbiome can have a profound impact on health, including the development of infections. Exploitation of these polymicrobial interactions has the potential to provide novel treatment and prevention strategies for infectious diseases. Enterococcus faecalis, a Gram-positive bacterium, and Candida albicans, a polymorphic fungus, occupy overlapping niches as ubiquitous constituents of the gastrointestinal and oral microbiome. Both species are also amongst the most important and problematic, opportunistic nosocomial pathogens and are often co-isolated during infection. Surprisingly, these two species antagonize each other’s …

Porphyromonas Gingivalis Infection In Gestational Diabetes Mellitus And Survival In Tobacco Smokers., Himabindu Gogeneni

Electronic Theses and Dissertations

This thesis contains a clinical project and distinct basic science project. Gestational diabetes mellitus occurs in 4% of pregnancies and increases the risk of birth defects, pre-term birth, and miscarriage. Gingivitis during pregnancy also increases the risk for poor pregnancy outcome. Gingivitis is a bacterial-induced disease, and specific plaque pathogens have been associated with systemic sequelae to periodontal inflammation. Therefore, we set out to monitor oral infection with three key periodontopathogens (Porphyromonas gingivalis, Filifactor alocis, and Treponema denticola) and the systemic inflammatory burden [C-reactive protein (CRP) in pregnant women with and without gingivitis and gestational diabetes. Gingivitis …

Discovering Antibacterial And Anti-Resistance Agents Targeting Multi-Drug Resistant Eskape Pathogens, Renee Fleeman

USF Tampa Graduate Theses and Dissertations

Antibiotic resistance has been a developing problem for mankind in recent decades and multi-drug resistant bacteria are now encountered that are resistant to all treatment options available. In 2014, the World Health Organization announced that this problem is driving us towards a “post-antibiotic era” that will change the face of modern medicine as we know it. If lack of novel antibiotic development and FDA approval continues, by the year 2050, 10 million people will die each year to an antimicrobial resistant bacterial infection. With lack of pharmaceutical industry involvement in developing novel antibiotics, the responsibility now lies within the academic …

Characterizing The Interaction Between Human Adenovirus E1a And The Transcriptional Repressor Bs69, Ali Zhang

Electronic Thesis and Dissertation Repository

Protein products of the Early Region 1A (E1A) gene in human adenovirus 5 (HAdV-5) are the first viral proteins expressed upon adenovirus infection. E1A disrupts many cellular physiological events by binding to and regulating an impressive number of host factors. Of particular interest is BS69, a repressor of E1A transactivation. Due to the strong interaction observed between E1A and BS69, I hypothesize that these two proteins function together to disrupt gene expression within an infected cell.

Using in silico modelling and a series of yeast two-hybrid assays, I determined that residues 112-119 of HAdV-5 E1A is the minimal interacting region …

Investigating Adenovirus E1a As An Rna Polymerase Ii C-Terminal Domain Mimic And Its Role In Transcription Activation, Kristianne Jc Galpin

Electronic Thesis and Dissertation Repository

Viruses rely on host cell machinery, often mimicking cellular components, in order to circumvent host cell defenses and hijack cellular processes. DNA viruses, such as human Adenovirus (hAdV), rely on RNA Polymerase II (RNAPII) to transcribe viral genes. RNAPII has a C-terminal domain (CTD), made up of highly conserved heptad repeats of tyrosine-serine-proline-threonine-serine-proline-serine (YSPTSPS). Post-translational modifications of residues within the CTD, including phosphorylation, coordinates the transcription cycle. Several viruses, including Human Immunodeficiency Virus (HIV), Human Cytomegalovirus (hCMV), Epstein-Bar Virus (EBV) and Herpes Simplex Virus (HSV), modify the phosphorylation state of the RNAPII CTD by hijacking cellular cyclin dependent kinases (CDKs) …

Function Of The Enterobactin Operon Of A. Actinomycetemcomitans In The Presence Of Catecholmines And Iron., Taylor Johnson

Electronic Theses and Dissertations

Background: Aggregatibacter actinomycetemcomitans (Aa) possesses a two-component system, QseBC, which is key in biofilm formation/virulence and is activated in the presence of iron-catecholamine complexes. Aa does not synthesize enterobactin, a catechol-based siderophore, yet possesses the machinery for recognition and uptake. We hypothesize that Aa is able to acquire iron by catecholamine mediation through the enterobactin receptor/transporter. Methods: By insertional mutation, we attempted to delete the enterobactin permease from the genome using suicide vector pJT1. A growth curve of truncated mutant ΔfepA was also conducted to observe growth in the presence of iron and catecholamines. Statistical significance was determined by ANOVA …

Comparative Evaluation Of The Antibacterial, Anti-Biofilm And Anti-Spore Effects Of Theaflavins And Palmitoyl-Egcg, Gabriella M. Appice

Seton Hall University Dissertations and Theses (ETDs)

Tea, one of the most common beverages, originates from the leaves of the Camellia sinensis plant. Two major groups of tea are fermented black tea and unfermented green tea. Theaflavins (TFs) are the major polyphenols present in black tea, while mono-palmitoyl-epigallocatechin-gallate (pEGCG) is a modified green tea polyphenol. In this study, the antibacterial effects of TF and pEGCG were evaluated against six selected bacteria, Staphylococcus epidermidis, Streptococcus mutans, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris, using an antibacterial assay. A viability assay using SYTOX® staining and flow cytometry was also used to determine the effect of these compounds …

Colicins - A Sound Antimicrobial Approach For The Prevention Of Catheter-Associated Urinary Tract Infections, Sandra M. Roy

Doctoral Dissertations

The emergence and spread of antibiotic resistance has created one of the greatest challenges in fighting infectious disease. We address the rise of antibiotic-resistant pathogens by examining the evolutionary history of a class of resistance determinants, the SHV b-lactamases. We isolated the genes that encode the SHV beta-lactamases (bla_SHV genes) from clinical settings and from an environment essentially devoid of antibiotic use. Our data suggests that, counter to current dogma, the use of antibiotics in the clinic is not creating these resistance genes; genes for antibiotic resistance already exist in nature and our use of antibiotics in clinical …

Amixicile Inhibits Anaerobic Bacteria Within An Oral Microbiome Derived From Patients With Chronic Periodontitis, Kane Ramsey

Theses and Dissertations

Periodontitis is a chronic inflammatory disease caused by pathogenic bacteria residing in a complex biofilm within a susceptible host. Amixicile is a non-toxic, readily bioavailable novel antimicrobial that targets strict anaerobes through inhibition of the activity of Pyruvate Ferredoxin Oxidoreductase (PFOR), a major enzyme mediating oxidative decarboxylation of pyruvate. Our study aimed to evaluate the efficacy of amixicile, when compared to metronidazole, in inhibiting the growth of bacteria present in a microbiome harvested from patients with chronic periodontitis.

Plaque samples were harvested from patients with severe chronic periodontitis and cultured under anaerobic conditions. The microbiomes were grown in the presence …

Microbiota, Diet And Medication In Human Gut Disorders, Adam Clooney

Theses

The microbiota, a community of micro-organisms in a particular environment, have been intensely researched in the past decade and interest appears to continue to increase. The human body is richly populated with bacterial cells (3.8x10'^) and alterations in these communities are associated with disease. The work presented in this thesis explores aspects of microbiota research methodologies with regard to optimisation and concerns over a lack of reproducibility. Additionally, we investigated the effects of medication, in particular Proton Pump Inhibitors, on the human gut microbiota, along with comparisons between the microbiota of patients with active and inactive Inflammatory Bowel Disease.

Microbiota …

In Search Of A Function For An Uncharacterized Conserved Protein In Streptococcus Sanguinis Sk36, Ayana Scott-Elliston

Theses and Dissertations

With the number of fully sequenced bacterial genomes increasing in the past 7 years, it has been discovered that a large percentage of the putative protein coding genes have no known function. This lack of knowledge leaves scientists with an incomplete understanding of bacteria. In this study, conserved hypothetical protein mutants from Streptococcus sanguinis SK36 were screened on solid media with various environmental conditions. From these screens, the candidate protein, SSA_2372, displayed a sensitivity to acidic conditions. Its homolog in Bacillus subtilis 168, BSU00030, also displayed a sensitivity to pH conditions at its acid tolerance extremes unlike its other homolog …

Novel Approaches To Mitigating Bacterial Biofilm Formation And Intercellular Communication, Stephen Kasper

Legacy Theses & Dissertations (2009 - 2024)

Long thought of as solitary single-cell organisms, it is now widely accepted that bacteria can act and cooperate as social organisms. Phenomena such as biofilm formation and quorum sensing (QS) are two intimately intertwined cooperative behaviors that significantly contribute to the pathogenesis of many bacteria. Biofilms are surface associated communities of bacteria encased in a secreted extracellular matrix, which provides several advantages over an individualized lifestyle, such as increased protection from antimicrobial agents as well as enhanced opportunity for the exchange of genetic material. Bacterial QS is a system of population-based communication through the production, sensing, and response to chemical …

A Systems Biology Approach For Predicting Essential Genes And Deciphering Their Dynamics Under Stress In Streptococcus Sanguinis, Fadi El-Rami

Theses and Dissertations

Infectious diseases are the top leading cause of death worldwide. Identifying essential genes, genes indispensable for survival, has been proven indispensable in defining new therapeutic targets against pathogens, major elements of the minimal set genome to be harnessed in synthetic biology, and determinants of evolutionary relationships of phylogenetically distant species. Thus, essentiality studies promise valuable revenues that can decipher much of biological complexities.

Taking advantage of the available microbial sequences and the essentiality studies conducted in various microbial models, we proposed a framework for the prediction of essential genes based on our experimentally verified knowledge of the pathways involved in …

Contribution Of A Class Ii Ribonucleotide Reductase To The Manganese Dependence Of Streptococcus Sanguinis, John L. Smith

Theses and Dissertations

Manganese-deficient Streptococcus sanguinis mutants exhibit a dramatic decrease in virulence for infective endocarditis and in aerobic growth in manganese-limited media. Loss of activity of a manganese-dependent, oxygen-dependent ribonucleotide reductase (RNR) could explain the decrease in virulence. When the genes encoding this RNR are deleted, there is no growth of the mutant in aerobic broth culture or in an animal model. Testing the contribution of the aerobic RNR to the phenotype of a manganese transporter mutant, a heterologous class II RNR from Lactobacillus leichmannii called NrdJ that requires B₁₂ rather than manganese as a cofactor was previously introduced into an …

Come Fly With Me: Using Amixicile To Target Periodontal Pathogens And Elucidating The Innate Immune Response In Drosophila Melanogaster, Kathryn Sinclair

Theses and Dissertations

Periodontal diseases (PD) affect 46% of American adults over age 30. These diseases cause symptoms including bleeding and swelling of the gums, bone resorption, and tooth loss, that affect quality of life and have a high economic burden. Periodontal diseases are caused by an imbalance in the oral microbiome, from a healthy state that contains anti-inflammatory commensals like Streptococcus gordonii and mitis, to a diseased state that has pro-inflammatory anaerobic pathogens including Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Tannerella forsythia. The latter initiate disease progression in the oral cavity. However, it’s the host immune …