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Infectious Disease

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Articles 61 - 90 of 189

Full-Text Articles in Medical Microbiology

Cryptococcal Antigen Testing In An Integrated Medical System: Eastern Wisconsin, Marianne Klumph, Brian Hoeynck, Dennis J. Baumgardner Jan 2020

Cryptococcal Antigen Testing In An Integrated Medical System: Eastern Wisconsin, Marianne Klumph, Brian Hoeynck, Dennis J. Baumgardner

Journal of Patient-Centered Research and Reviews

Cryptococcosis is a serious environmentally acquired endemic fungal infection commonly associated with immunocompromised hosts. Little is known regarding frequency or distribution in Wisconsin. We explored the geodemographic and clinical features of patients tested with cryptococcal antigen tests (CrAg) — previously shown to be >90% sensitive and >90% specific — within a large health care system located in eastern Wisconsin. To examine this, we retrospectively analyzed 1465 CrAg tests on 1211 unique patients (female: 50.2%; white race: 73.9%; mean age: 53.7 ± 16.5 years). At least one CrAg result was positive in 23 of 1211 patients (1.9%). From these, 21 of …


Prevalence Of The Hypervirulent Nap1/Bi/027 Strain Of C. Difficile In Southwestern Virginia And Risk Factors Associated With Infection, Andrew O. Hanna, Anthony Baffoe-Bonnie, Shikha Vasudeva Jan 2020

Prevalence Of The Hypervirulent Nap1/Bi/027 Strain Of C. Difficile In Southwestern Virginia And Risk Factors Associated With Infection, Andrew O. Hanna, Anthony Baffoe-Bonnie, Shikha Vasudeva

Graduate Medical Education (GME) Resident and Fellow Research Day Posters

C. difficile infection (CDI) incidence has increased over the last several decades. The BI/NAP1/027 ribotype was discovered in 2005 and has since been responsible for multiple outbreaks in the US and Canada. This subtype of C. Difficile is known to be more virulent in vivo and produce more severe disease. Limited regional data of the prevalence of this ribotype is available, which could help guide treatment. Using infection control data from a large regional hospital and a VA medical center, this study documented the prevalence of the 027 ribotype in Southwest Virginia. Patients were included if they were tested at …


First-Time Characterization Of Viable But Non-Culturable Proteus Mirabilis: Induction And Resuscitation, Reham Wasfi, G. R. Abdellatif, H. M. Elshishtawy, Hossam M. Ashour Jan 2020

First-Time Characterization Of Viable But Non-Culturable Proteus Mirabilis: Induction And Resuscitation, Reham Wasfi, G. R. Abdellatif, H. M. Elshishtawy, Hossam M. Ashour

USF St. Petersburg Campus Faculty Publications

Pathogenic bacteria can enter into a viable but non-culturable (VBNC) state under unfavourable conditions. Proteus mirabilis is responsible for dire clinical consequences including septicaemia, urinary tract infections and pneumonia, but is not a species previously known to enter VBNC state. We suggested that stress-induced P. mirabilis can enter a VBNC state in which it retains virulence. P. mirabilis isolates were incubated in extreme osmotic pressure, starvation, low temperature and low pH to induce a VBNC state. Resuscitation was induced by temperature upshift and inoculation in tryptone soy broth with Tween 20 and brain heart infusion broth. Cellular ultrastructure and gene …


Tick-Borne Infections In New Hampshire: An Evaluation Of The Diagnostic Process In A Local Patient Population, Katherine Anderson Jan 2020

Tick-Borne Infections In New Hampshire: An Evaluation Of The Diagnostic Process In A Local Patient Population, Katherine Anderson

Honors Theses and Capstones

Overall, approximately 95 percent of reported cases of vector-borne disease were associated with ticks, making these the most medically important group of arthropods in the United States.1 Despite the prevalence of tick-borne infections, the process for the diagnosis of this condition is not well studied. This study aims to analyze data from a pool of 100 patients who underwent testing for tick-borne disease in the same institution in Dover, New Hampshire during the most recent peak tick season of 2019. Information utilized in this study included: patient age, sex, location of testing (inpatient versus outpatient), diagnostic testing methods used …


Inactivated Rabies Virus-Based Ebola Vaccine Preserved By Vaporization Is Heat-Stable And Immunogenic Against Ebola And Protects Against Rabies Challenge., Drishya Kurup, Christine R. Fisher, Todd G. Smith, Tiago Abreu-Mota, Yong Yang, Felix R. Jackson, Nadia Gallardo-Romero, Richard Franka, Victor Bronshtein, Matthias J. Schnell Sep 2019

Inactivated Rabies Virus-Based Ebola Vaccine Preserved By Vaporization Is Heat-Stable And Immunogenic Against Ebola And Protects Against Rabies Challenge., Drishya Kurup, Christine R. Fisher, Todd G. Smith, Tiago Abreu-Mota, Yong Yang, Felix R. Jackson, Nadia Gallardo-Romero, Richard Franka, Victor Bronshtein, Matthias J. Schnell

Department of Microbiology and Immunology Faculty Papers

BACKGROUND: Ebola virus (EBOV) is a highly lethal member of the Filoviridae family associated with human hemorrhagic disease. Despite being a sporadic disease, it caused a large outbreak in 2014-2016 in West Africa and another outbreak recently in the Democratic Republic of Congo. Several vaccine candidates are currently in preclinical and clinical studies but none are stable without cold chain storage.

METHODS: We used preservation by vaporization (PBV), a novel processing technology to heat-stabilize FiloRab1 (inactivated rabies-based Ebola vaccine), a candidate Ebola vaccine, and stored the vials at temperatures ranging from 4°C to 50°C for 10 days to 12 months. …


Dmbt1 Inhibition Of Pseudomonas Aeruginosa Twitching Motility Involves Its N-Glycosylation And Cannot Be Conferred By The Scavenger Receptor Cysteine-Rich Bacteria-Binding Peptide Domain., Jianfang Li, Stephanie J Wan, Matteo M E Metruccio, Sophia Ma, Kamran Nazmi, Floris J Bikker, David J. Evans, Suzanne M J Fleiszig Sep 2019

Dmbt1 Inhibition Of Pseudomonas Aeruginosa Twitching Motility Involves Its N-Glycosylation And Cannot Be Conferred By The Scavenger Receptor Cysteine-Rich Bacteria-Binding Peptide Domain., Jianfang Li, Stephanie J Wan, Matteo M E Metruccio, Sophia Ma, Kamran Nazmi, Floris J Bikker, David J. Evans, Suzanne M J Fleiszig

Faculty Publications & Research of the TUC College of Pharmacy

The scavenging capacity of glycoprotein DMBT1 helps defend mucosal epithelia against microbes. DMBT1 binding to multiple bacterial species involves its conserved Scavenger Receptor Cysteine-Rich (SRCR) domains, localized to a 16-mer consensus sequence peptide, SRCRP2. Previously, we showed that DMBT1 bound Pseudomonas aeruginosa pili, and inhibited twitching motility, a pilus-mediated movement important for virulence. Here, we determined molecular characteristics required for twitching motility inhibition. Heat-denatured DMBT1 lost capacity to inhibit twitching motility and showed reduced pili binding (~40%). Size-exclusion chromatography of Lys-C-digested native DMBT1 showed that only high-Mw fractions retained activity, suggesting involvement of the N-terminal containing repeated SRCR domains with …


Severity Of Disease And Mortality For Hospitalized Patients With Community-Acquired Viral Pneumonia Compared To Patients With Community-Acquired Bacterial Pneumonia, Richard Y. Kim, Thomas Chandler, Stephen P. Furmanek, Timothy Lee Wiemken, Rodrigo Cavallazzi Feb 2019

Severity Of Disease And Mortality For Hospitalized Patients With Community-Acquired Viral Pneumonia Compared To Patients With Community-Acquired Bacterial Pneumonia, Richard Y. Kim, Thomas Chandler, Stephen P. Furmanek, Timothy Lee Wiemken, Rodrigo Cavallazzi

The University of Louisville Journal of Respiratory Infections

Background: There exists a large body of literature to help identify, diagnose, treat, and manage community-acquired pneumonia (CAP). Despite this, there is little data that directly compares the clinical syndromes and complications of pure bacterial pneumonia to pure viral pneumonia. Our study compares the clinical presentation, morbidity and mortality of viral vs. bacterial etiologies of CAP.

Methods: This was a secondary data analysis of the Community-Acquired Pneumonia Organization (CAPO) international study database. Data was collected concerning patient demographics, physical examination findings, laboratory findings, radiological findings, severity of illness, and clinical outcomes and stratified according to the two study groups, CAVP …


Non-Neutralizing Antibodies Elicited By Recombinant Lassa-Rabies Vaccine Are Critical For Protection Against Lassa Fever., Tiago Abreu-Mota, Katie R. Hagen, Kurt Cooper, Peter B. Jahrling, Gene Tan, Christoph Wirblich, Reed F. Johnson, Matthias J. Schnell Dec 2018

Non-Neutralizing Antibodies Elicited By Recombinant Lassa-Rabies Vaccine Are Critical For Protection Against Lassa Fever., Tiago Abreu-Mota, Katie R. Hagen, Kurt Cooper, Peter B. Jahrling, Gene Tan, Christoph Wirblich, Reed F. Johnson, Matthias J. Schnell

Department of Microbiology and Immunology Faculty Papers

Lassa fever (LF), caused by Lassa virus (LASV), is a viral hemorrhagic fever for which no approved vaccine or potent antiviral treatment is available. LF is a WHO priority disease and, together with rabies, a major health burden in West Africa. Here we present the development and characterization of an inactivated recombinant LASV and rabies vaccine candidate (LASSARAB) that expresses a codon-optimized LASV glycoprotein (coGPC) and is adjuvanted by a TLR-4 agonist (GLA-SE). LASSARAB elicits lasting humoral response against LASV and RABV in both mouse and guinea pig models, and it protects both guinea pigs and mice against LF. We …


Atherosclerosis In Subjects Newly Diagnosed With Human Immunodeficiency Virus Infection., Tatiana V Kirichenko, Veronika A Myasoedova, Tatiana E Shimonova, Alexandra A Melnichenko, Dmitri Sviridov, Igor A Sobenin, Alexey I Mazus, Alexander N Orekhov, Michael I Bukrinsky Aug 2018

Atherosclerosis In Subjects Newly Diagnosed With Human Immunodeficiency Virus Infection., Tatiana V Kirichenko, Veronika A Myasoedova, Tatiana E Shimonova, Alexandra A Melnichenko, Dmitri Sviridov, Igor A Sobenin, Alexey I Mazus, Alexander N Orekhov, Michael I Bukrinsky

Microbiology, Immunology, and Tropical Medicine Faculty Publications

HIV infection is associated with the increased risk of cardiovascular disease (CVD), even in patients successfully treated with the combination antiretroviral therapy (cART). However, the relationship between HIV, cART, and pathogenesis of CVD remains controversial. In the present study, we evaluated the carotid intima-media thickness (CIMT), a surrogate marker of atherosclerosis, in HIV-infected subjects receiving or not receiving cART. One hundred nine newly diagnosed HIV-infected subjects and one hundred nine uninfected age-matched controls (all males) without the history of CVD, hypertension, or diabetes were recruited into the present study. Cross-sectional analysis at baseline (BL) showed significantly increased levels of triglycerides …


Coping With Chronic Fungal Rhinosinusitis: Diagnosis To Therapy, Veronica Corcino, Leslie Beavin, Shengli Lu, Ashley Ross, Carmen V. Sciortino Jr. Aug 2018

Coping With Chronic Fungal Rhinosinusitis: Diagnosis To Therapy, Veronica Corcino, Leslie Beavin, Shengli Lu, Ashley Ross, Carmen V. Sciortino Jr.

The University of Louisville Journal of Respiratory Infections

No abstract provided.


A Comparison Of Oral And Intravenous Mouse Models Of Listeriosis, Michelle G. Pitts, Sarah E. F. D'Orazio Mar 2018

A Comparison Of Oral And Intravenous Mouse Models Of Listeriosis, Michelle G. Pitts, Sarah E. F. D'Orazio

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Listeria monocytogenes is one of several enteric microbes that is acquired orally, invades the gastric mucosa, and then disseminates to peripheral tissues to cause systemic disease in humans. Intravenous (i.v.) inoculation of mice with L. monocytogenes has been the most widely-used small animal model of listeriosis over the past few decades. The infection is highly reproducible and has been invaluable in deciphering mechanisms of adaptive immunity in vivo, particularly CD8+ T cell responses to intracellular pathogens. However, the i.v. model completely bypasses the gut phase of the infection. Recent advances in generating both humanized mice and murinized bacteria, as well …


Characterization Of Different Molecular Markers For Identification Of Salmonella Enterica Serovar Typhi In Pakistani Population, Faizan Muttiullah, Fida Muhammad Khan, Fakhar-I- Abbas, Sabiha Shamim Sep 2017

Characterization Of Different Molecular Markers For Identification Of Salmonella Enterica Serovar Typhi In Pakistani Population, Faizan Muttiullah, Fida Muhammad Khan, Fakhar-I- Abbas, Sabiha Shamim

Journal of Bioresource Management

Typhoid is caused by Salmonella enterica serovar Typhi that is usually diagnosed by using serologic and immuno-chromatographic techniques in developing counties including Pakistan, which is thought to be an unreliable diagnostic method. For accurate diagnosis we used molecular techniques to amplify 204 bp StyR-36 and 498 bp flagellin gene for the identification of Salmonella enterica serovar Typhi. This study was done on 58 individuals diagnosed positive of typhoid via serologic tests and 50 healthy individuals as a control group. Success rate of amplification for flagellin gene was 77.58% while that for StyR-36 gene was 68.97% showing that flagellin gene primer …


Analysis Of The Local And Systemic Cytokine Response Profiles In Patients With Community-Acquired Pneumonia. Relationship With Disease Severity And Outcomes., Rafael Fernandez-Botran, Timothy Lee Wiemken, Robert R. Kelley, Paula Peyrani, Jose Bordon, Rodrigo Cavallazzi, Julio A. Ramirez May 2017

Analysis Of The Local And Systemic Cytokine Response Profiles In Patients With Community-Acquired Pneumonia. Relationship With Disease Severity And Outcomes., Rafael Fernandez-Botran, Timothy Lee Wiemken, Robert R. Kelley, Paula Peyrani, Jose Bordon, Rodrigo Cavallazzi, Julio A. Ramirez

The University of Louisville Journal of Respiratory Infections

The goals of this study were to investigate the relationship of systemic and local cytokine responses with time to clinical stability (TCS) in patients with community-acquired pneumonia (CAP) and to develop a model to integrate multiple cytokine data into “cytokine response profiles” based on local vs. systemic and pro- vs. anti-inflammatory cytokine patterns in order to better understand their relationships with measures of CAP severity and outcomes. Forty hospitalized patients enrolled through the Community Acquired Pneumonia Inflammatory Study Group (CAPISG) were analyzed. Based on the ranked distribution of the levels of eight different pro-inflammatory cytokines and chemokines (IL-1b, IL-6, IL-8, …


Chat Expression In Chlamydia Muridarum-Infected Female Murine Genital Tract, Hallie Sartain May 2017

Chat Expression In Chlamydia Muridarum-Infected Female Murine Genital Tract, Hallie Sartain

Undergraduate Honors Theses

Chlamydia trachomatis is the most prevalent agent of bacterial sexually transmitted infections in the world. However, a profuse number of cases are unreported, as the infection is often asymptomatic. Sequelae such as pelvic inflammatory disease, an increased risk of cervical cancer, premature birth, and perinatal infections in pregnant women can occur. Inflammation occurs in the body in response to infection or injury. Although inflammation can lead to some unwanted secondary effects, such as pain, it serves to return the body to homeostasis by restoring injured tissues and eliminating pathogens. One recently identified connection between the central nervous system and the …


A New Class Of Inhibitors Of The Arac Family Virulence Regulator Vibrio Cholerae Toxt, Anne K. Woodbrey, Evans O. Onyango, Maria Pellegrini, Gabriela Kovacikova, Ronald Taylor, Gordon Gribble, F. Jon Kull Mar 2017

A New Class Of Inhibitors Of The Arac Family Virulence Regulator Vibrio Cholerae Toxt, Anne K. Woodbrey, Evans O. Onyango, Maria Pellegrini, Gabriela Kovacikova, Ronald Taylor, Gordon Gribble, F. Jon Kull

Dartmouth Scholarship

Vibrio cholerae is responsible for the diarrheal disease cholera that infects millions of people worldwide. While vaccines protecting against cholera exist, and oral rehydration therapy is an effective treatment method, the disease will remain a global health threat until long-term solutions such as improved sanitation and access to clean water become widely available. Because of this, there is a pressing need for potent therapeutics that can either mitigate cholera symptoms, or act prophylactically to prevent the virulent effects of a cholera infection. Here we report the design, synthesis, and characterization of a set of compounds that bind and inhibit ToxT, …


Freshwater Fungal Infections, Dennis J. Baumgardner Jan 2017

Freshwater Fungal Infections, Dennis J. Baumgardner

Journal of Patient-Centered Research and Reviews

Fungal infections as a result of freshwater exposure or trauma are fortunately rare. Etiologic agents are varied, but commonly include filamentous fungi and Candida. This narrative review describes various sources of potential freshwater fungal exposure and the diseases that may result, including fungal keratitis, acute otitis externa and tinea pedis, as well as rare deep soft tissue or bone infections and pulmonary or central nervous system infections following traumatic freshwater exposure during natural disasters or near-drowning episodes. Fungal etiology should be suspected in appropriate scenarios when bacterial cultures or molecular tests are normal or when the infection worsens or …


Genomes Of Fasciola Hepatica From The Americas Reveal Colonization With Neorickettsia Endobacteria Related To The Agents Of Potomac Horse And Human Sennetsu Fevers., Samantha N Mcnulty, Jose F Tort, Gabriel Rinaldi, Bruce A Rosa, Victoria H. Mann, Patricia S. Latham, Paul J. Brindley, +Several Additional Authors Jan 2017

Genomes Of Fasciola Hepatica From The Americas Reveal Colonization With Neorickettsia Endobacteria Related To The Agents Of Potomac Horse And Human Sennetsu Fevers., Samantha N Mcnulty, Jose F Tort, Gabriel Rinaldi, Bruce A Rosa, Victoria H. Mann, Patricia S. Latham, Paul J. Brindley, +Several Additional Authors

Microbiology, Immunology, and Tropical Medicine Faculty Publications

Food borne trematodes (FBTs) are an assemblage of platyhelminth parasites transmitted through the food chain, four of which are recognized as neglected tropical diseases (NTDs). Fascioliasis stands out among the other NTDs due to its broad and significant impact on both human and animal health, as Fasciola sp., are also considered major pathogens of domesticated ruminants. Here we present a reference genome sequence of the common liver fluke, Fasciola hepatica isolated from sheep, complementing previously reported isolate from cattle. A total of 14,642 genes were predicted from the 1.14 GB genome of the liver fluke. Comparative genomics indicated that F. …


Immune- And Nonimmune-Compartment-Specific Interferon Responses Are Critical Determinants Of Herpes Simplex Virus-Induced Generalized Infections And Acute Liver Failure, Zachary M. Parker, Tracy Jo Pasieka, George A. Parker, David A. Leib Sep 2016

Immune- And Nonimmune-Compartment-Specific Interferon Responses Are Critical Determinants Of Herpes Simplex Virus-Induced Generalized Infections And Acute Liver Failure, Zachary M. Parker, Tracy Jo Pasieka, George A. Parker, David A. Leib

Dartmouth Scholarship

The interferon (IFN) response to viral pathogens is critical for host survival. In humans and mouse models, defects in IFN responses can result in lethal herpes simplex virus 1 (HSV-1) infections, usually from encephalitis. Although rare, HSV-1 can also cause fulminant hepatic failure, which is often fatal. Although herpes simplex encephalitis has been extensively studied, HSV-1 generalized infections and subsequent acute liver failure are less well understood. We previously demonstrated that IFN-αβγR-/- mice are exquisitely susceptible to liver infection following corneal infection with HSV-1. In this study, we used bone marrow chimeras of IFN-αβγR-/- (AG129) and wild-type (WT; 129SvEv) mice …


Effects Of Tcpb Mutations On Biogenesis And Function Of The Toxin-Coregulated Pilus, The Type Ivb Pilus Of Vibrio Cholerae, Yang Gao, Caitlyn A. Hauke, Jarrad M. Marles, Ronald K. Taylor Aug 2016

Effects Of Tcpb Mutations On Biogenesis And Function Of The Toxin-Coregulated Pilus, The Type Ivb Pilus Of Vibrio Cholerae, Yang Gao, Caitlyn A. Hauke, Jarrad M. Marles, Ronald K. Taylor

Dartmouth Scholarship

Vibrio cholerae is the etiological agent of the acute intestinal disorder cholera. The toxin-coregulated pilus (TCP), a type IVb pilus, is an essential virulence factor of V. cholerae. Recent work has shown TcpB is a large minor pilin encoded within the tcp operon. TcpB contributes to efficient pilus formation and is essential for all TCP functions. Here we have initiated a detailed, targeted mutagenesis approach to further characterize this salient TCP component. We have identified (thus far) 20 residues of TcpB, which affect either the steady state level of TcpB or alter one or more TCP functions. This study …


Cyclic Di-Gmp-Regulated Periplasmic Proteolysis Of A Pseudomonas Aeruginosa Type Vb Secretion System Substrate, Richard B. Cooley, T. Jarrod Smith, Wilfred Leung, Valerie Tierney, Bradley Borlee, George A. O'Toole, Holger Sondermann Jun 2016

Cyclic Di-Gmp-Regulated Periplasmic Proteolysis Of A Pseudomonas Aeruginosa Type Vb Secretion System Substrate, Richard B. Cooley, T. Jarrod Smith, Wilfred Leung, Valerie Tierney, Bradley Borlee, George A. O'Toole, Holger Sondermann

Dartmouth Scholarship

We previously identified a second-messenger-regulated signaling system in the environmental bacterium Pseudomonas fluorescens which controls biofilm formation in response to levels of environmental inorganic phosphate. This system contains the transmembrane cyclic di-GMP (c-di-GMP) receptor LapD and the periplasmic protease LapG. LapD regulates LapG and controls the ability of this protease to process a large cell surface adhesin protein, LapA. While LapDG orthologs can be identified in diverse


The Pseudomonas Aeruginosa Efflux Pump Mexghi-Opmd Transports A Natural Phenazine That Controls Gene Expression And Biofilm Development, Hassan Sakhtah, Leslie Koyama, Yihan Zhang, Diana K. Morales, Blanche Fields, Alexa Price-Whelan, Deborah Hogan Jun 2016

The Pseudomonas Aeruginosa Efflux Pump Mexghi-Opmd Transports A Natural Phenazine That Controls Gene Expression And Biofilm Development, Hassan Sakhtah, Leslie Koyama, Yihan Zhang, Diana K. Morales, Blanche Fields, Alexa Price-Whelan, Deborah Hogan

Dartmouth Scholarship

Redox-cycling compounds, including endogenously produced phenazine antibiotics, induce expression of the efflux pump MexGHI-OpmD in the opportunistic pathogen Pseudomonas aeruginosa Previous studies of P. aeruginosa virulence, physiology, and biofilm development have focused on the blue phenazine pyocyanin and the yellow phenazine-1-carboxylic acid (PCA). In P. aeruginosa phenazine biosynthesis, conversion of PCA to pyocyanin is presumed to proceed through the intermediate 5-methylphenazine-1-carboxylate (5-Me-PCA), a reactive compound that has eluded detection in most laboratory samples. Here, we apply electrochemical methods to directly detect 5-Me-PCA and find that it is transported by MexGHI-OpmD in P. aeruginosa strain PA14 planktonic and biofilm cells. We …


Hiv Vaccines: Progress, Limitations And A Crispr/Cas9 Vaccine, Omar A. Garcia Martinez May 2016

Hiv Vaccines: Progress, Limitations And A Crispr/Cas9 Vaccine, Omar A. Garcia Martinez

Biology: Student Scholarship & Creative Works

ABSTRACT: The HIV-1 pandemic continues to thrive due to ineffective HIV-1 vaccines. Historically, the world’s most infectious diseases, such as polio and smallpox, have been eradicated or have come close to eradication due to the advent of effective vaccines. Highly active antiretroviral therapy is able to delay the onset of AIDS but can neither rid the body of HIV-1 proviral DNA nor prevent further transmission. A prophylactic vaccine that prevents the various mechanisms HIV-1 has to evade and attack our immune system is needed to end the HIV-1 pandemic. Recent advances in engineered nuclease systems, like the CRISPR/Cas9 system, have …


Intimin Likely Used To Cause Disease During Competition With Commensal Escherichia Coli, Dominique J. Richburg Apr 2016

Intimin Likely Used To Cause Disease During Competition With Commensal Escherichia Coli, Dominique J. Richburg

Senior Honors Theses

The intimin gene in the Locus of Enterocyte Effacement (LEE) island of pathogenicity is the primary attachment mechanism in Citrobacter rodentium. Intimin is a bacterial adhesin (protein) that attaches to obtain a niche/nutrient and thrive within the intestine. Intimin was deleted within C. rodentium to study colonization and pathogenesis in the murine intestine. Additionally, C. rodentium is an attaching/effacing pathogen, and a useful murine model in understanding Enterohemorrhagic Escherichia coli (EHEC) infection in humans. E. coli and C. rodentium cause gastroenteritis in humans and mice, respectively. C. rodentium is a murine pathogen commonly used to model gastrointestinal disease because …


The Gras Sensor In Staphylococcus Aureus Mediates Resistance To Host Defense Peptides Differing In Mechanisms Of Action, Siyang Chaili, Ambrose L. L. Cheung, Arnold S. Bayer, Yan Q. Xiong, Alan Waring, Guido Memmi, Niles Donegan Feb 2016

The Gras Sensor In Staphylococcus Aureus Mediates Resistance To Host Defense Peptides Differing In Mechanisms Of Action, Siyang Chaili, Ambrose L. L. Cheung, Arnold S. Bayer, Yan Q. Xiong, Alan Waring, Guido Memmi, Niles Donegan

Dartmouth Scholarship

Staphylococcus aureus uses the two-component regulatory system GraRS to sense and respond to host defense peptides (HDPs). However, the mechanistic impact of GraS or its extracellular sensing loop (EL) on HDP resistance is essentially unexplored. Strains with null mutations in the GraS holoprotein (ΔgraS) or its EL (ΔEL) were compared for mechanisms of resistance to HDPs of relevant immune sources: neutrophil α-defensin (human neutrophil peptide 1 [hNP-1]), cutaneous β-defensin (human β-defensin 2 [hBD-2]), or the platelet kinocidin congener RP-1. Actions studied by flow cytometry included energetics (ENR); membrane permeabilization (PRM); annexin V binding (ANX), and cell death protease activation (CDP). …


Inhibition Of Bacterial Growth And Prevention Of Bacterial Adhesion With Localized Nitric Oxide Delivery, Julia Osborne Jan 2016

Inhibition Of Bacterial Growth And Prevention Of Bacterial Adhesion With Localized Nitric Oxide Delivery, Julia Osborne

Dissertations, Master's Theses and Master's Reports

Bacterial infections continue to be a problem at the site of an indwelling medical device, and over the years, various bacterial strains have become more resistant to current antibiotic treatments. Bacterial infection at an indwelling medical device can be dangerous and affect the performance of the medical device which can ultimately lead to the failure of the device due to bacterial resistance to treatment.

Nitric Oxide (NO) has been shown to possess antibacterial properties to prevent and inhibit bacterial growth. NO releasing coatings on indwelling medical devices could provide a reduction in bacterial infections that occur at the device site …


Parasite Manipulation Of The Invariant Chain And The Peptide Editor H2-Dm Affects Major Histocompatibility Complex Class Ii Antigen Presentation During Toxoplasma Gondii Infection, Louis-Philippe Leroux, Manami Nishi, Sandy El-Hage, Barbara A. Fox, David I Bzik, Florence Dzierszinsk Oct 2015

Parasite Manipulation Of The Invariant Chain And The Peptide Editor H2-Dm Affects Major Histocompatibility Complex Class Ii Antigen Presentation During Toxoplasma Gondii Infection, Louis-Philippe Leroux, Manami Nishi, Sandy El-Hage, Barbara A. Fox, David I Bzik, Florence Dzierszinsk

Dartmouth Scholarship

Toxoplasma gondii is an obligate intracellular protozoan parasite. This apicomplexan is the causative agent of toxoplasmosis, a leading cause of central nervous system disease in AIDS. It has long been known that T. gondii interferes with major histocompatibility complex class II (MHC-II) antigen presentation to attenuate CD4(+) T cell responses and establish persisting infections. Transcriptional downregulation of MHC-II genes by T. gondii was previously established, but the precise mechanisms inhibiting MHC-II function are currently unknown. Here, we show that, in addition to transcriptional regulation of MHC-II, the parasite modulates the expression of key components of the MHC-II antigen presentation pathway, …


A Self-Lysis Pathway That Enhances The Virulence Of A Pathogenic Bacterium, Kirsty A. Mcfarland, Emily L. Dolben, Michele Leroux, Tracy K. Kambara, Kathryn Ramsey, Robin Kirkpatrick, Joseph Mougous, Deborah Hogan, Simon Dove Jul 2015

A Self-Lysis Pathway That Enhances The Virulence Of A Pathogenic Bacterium, Kirsty A. Mcfarland, Emily L. Dolben, Michele Leroux, Tracy K. Kambara, Kathryn Ramsey, Robin Kirkpatrick, Joseph Mougous, Deborah Hogan, Simon Dove

Dartmouth Scholarship

In mammalian cells, programmed cell death (PCD) plays important roles in development, in the removal of damaged cells, and in fighting bacterial infections. Although widespread among multicellular organisms, there are relatively few documented instances of PCD in bacteria. Here we describe a potential PCD pathway in Pseudomonas aeruginosa that enhances the ability of the bacterium to cause disease in a lung infection model. Activation of the system can occur in a subset of cells in response to DNA damage through cleavage of an essential transcription regulator we call AlpR. Cleavage of AlpR triggers a cell lysis program through de-repression of …


Links Between Anr And Quorum Sensing In Pseudomonas Aeruginosa Biofilms, John H. Hammond, Emily F. Dolben, T. Jarrod Smith, Sabin Bhuju, Deborah Hogan Jun 2015

Links Between Anr And Quorum Sensing In Pseudomonas Aeruginosa Biofilms, John H. Hammond, Emily F. Dolben, T. Jarrod Smith, Sabin Bhuju, Deborah Hogan

Dartmouth Scholarship

In Pseudomonas aeruginosa, the transcription factor Anr controls the cellular response to low oxygen or anoxia. Anr activity is high in oxygen-limited environments, including biofilms and populations associated with chronic infections, and Anr is necessary for persistence in a model of pulmonary infection. In this study, we characterized the Anr regulon in biofilm-grown cells at 1% oxygen in the laboratory strain PAO1 and in a quorum sensing (QS)-deficient clinical isolate, J215. As expected, transcripts related to denitrification, arginine fermentation, high-affinity cytochrome oxidases, and CupA fimbriae were lower in the Δanr derivatives. In addition, we observed that transcripts associated with quorum …


Nonreplicating, Cyst-Defective Type Ii Toxoplasma Gondii Vaccine Strains Stimulate Protective Immunity Against Acute And Chronic Infection, Barbara Andrea Fox, David J. Bzik May 2015

Nonreplicating, Cyst-Defective Type Ii Toxoplasma Gondii Vaccine Strains Stimulate Protective Immunity Against Acute And Chronic Infection, Barbara Andrea Fox, David J. Bzik

Dartmouth Scholarship

Live attenuated vaccine strains, such as type I nonreplicating uracil auxotroph mutants, are highly effective in eliciting lifelong immunity to virulent acute infection by Toxoplasma gondii. However, it is currently unknown whether vaccine-elicited immunity can provide protection against acute infection and also prevent chronic infection. To address this problem, we developed nonreverting, nonreplicating, live attenuated uracil auxotroph vaccine strains in the type II Δku80 genetic background by targeting the deletion of the orotidine 5′-monophosphate decarboxylase (OMPDC) and uridine phosphorylase (UP) genes. Deletion of OMPDC induced a severe uracil auxotrophy with loss of replication, loss of …


Coculture Of Staphylococcus Aureus With Pseudomonas Aeruginosa Drives S. Aureus Towards Fermentative Metabolism And Reduced Viability In A Cystic Fibrosis Model, Laura M. Filkins, Jyoti A. Graber, Daniel G. Olson, Emily L. Dolben, Lee Lynd, Sabin Bhuju, George A. O'Toole Apr 2015

Coculture Of Staphylococcus Aureus With Pseudomonas Aeruginosa Drives S. Aureus Towards Fermentative Metabolism And Reduced Viability In A Cystic Fibrosis Model, Laura M. Filkins, Jyoti A. Graber, Daniel G. Olson, Emily L. Dolben, Lee Lynd, Sabin Bhuju, George A. O'Toole

Dartmouth Scholarship

The airways of patients with cystic fibrosis are colonized with diverse bacterial communities that change dynamically during pediatric years and early adulthood. Staphylococcus aureus is the most prevalent pathogen during early childhood, but during late teens and early adulthood, a shift in microbial composition occurs leading to Pseudomonas aeruginosa community predominance in ∼50% of adults. We developed a robust dual-bacterial in vitro coculture system of P. aeruginosa and S. aureus on monolayers of human bronchial epithelial cells homozygous for the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) mutation to better model the mechanisms of this interaction. We show that P. …