Bacterial Infections and Mycoses Commons^™

Investigation Of Clinically Relevant Fluconazole Resistance Mechanisms In The Fungal Pathogen Candida Parapsilosis, Laura Anne Doorley

Theses and Dissertations (ETD)

Invasive candidiasis is a severe fungal infection associated with significant morbidity and mortality, particularly among the critically ill and immunocompromised. Candida parapsilosis is the most common non-albicans species causing invasive Candida infections in pediatric and neonatal populations worldwide and is particularly common in the countries of South America, Western Asia, Mediterranean Europe, and Southern Africa. For many of these countries, fluconazole and other triazoles are the first line antifungal agents used for effective treatment of invasive Candida infection. Until recently, rates of fluconazole resistance among C. parapsilosis isolates were relatively low, therefore the determination of clinically relevant resistance mechanisms in …

Physiologically-Based Pharmacokinetic (Pbpk) Modeling For The Preclinical Development Of Spectinamide Antibiotics, Keyur R. Parmar

Theses and Dissertations (ETD)

Despite being an ancient disease caused by Mycobacterium tuberculosis (Mtb) and after decades of research, tuberculosis (TB) still affects millions of people every year worldwide. In 2018, the World Health Organization (WHO) reported that 10 million people developed tuberculosis and 1.5 million died of the disease. With the increase in the multidrug-resistant (MDR) and extensively drug-resistant (XDR) cases, the treatment for TB with the standard first and second-line therapy is becoming increasingly difficult. Therefore, there is an urgent need to find new anti-TB drugs as combination partners of existing and experimental classes of antimicrobial agents to shorten and simplify the …

Computer-Aided Drug Discovery For Helicobacter Pylori, Nicole Ann Vita

Theses and Dissertations (ETD)

Helicobacter pylori is a high-priority drug-resistant pathogen and is currently the only bacteria considered to be a class I carcinogen and there is a critical need to identify novel chemical matter to treat H. pylori infections. Hp is responsible for greater than 60% of gastric cancer related deaths and 89% of all gastric cancer morbidities. In a previous study, our lab identified novel Hp thienopyrmidine inhibitors that target respiratory complex I, an essential enzyme in respiration. Respiratory complex I is a large asymmetric multidomain and membrane bound enzyme and due to these innate features, it is not practical for biophysical …

A Cloning-Free Recyclable System For Crispr-Cas9 Mediated Mutant And Reversion Construction In Candida Albicans Clinical Isolates, Amanda K. Vogel

Theses and Dissertations (ETD)

Candida albicans is a ubiquitous opportunistic fungal pathogen and one of the most prevalent causes of fungal diseases worldwide. The reference isolate SC5314 is one of the most widely used strains for both experimental and genetic studies, but it is becoming increasingly evident that genetic diversity in clinical isolates plays an important role in antifungal resistance, virulence, and pathogenicity. These recent discoveries highlight the need for genetic tools that are capable of investigating genes in multiple strain backgrounds. Here we build on the SAT1-flipper method and combine it with CRISPR-Cas9 technology to achieve cloning-free homozygous deletion in a single transformation …

Nursing Perspectives And Opinions On Early Or Delayed Sepsis Treatment: A Mixed Methods Approach, Pamela L. Harris

Theses and Dissertations (ETD)

Purpose. Each year at least 1.7 million adults in America develop sepsis. Sepsis can lead to life threatening organ dysfunction, severe hypotension, and death when severe sepsis or septic shock is involved. Sepsis is responsible for 50% of acute kidney injury (AKI), which is the most common form of organ dysfunction seen in critical care. Sepsis associated AKI results in loss of, or decreased renal function, is associated with adverse long-term outcomes, and carries a higher mortality rate than non-septic AKI, sepsis without AKI, or septic shock without AKI. Surviving sepsis guidelines suggests a 1-hour window from the time of …

Sepsis: Do The Clinical Criteria Support The Medical Coding?, April M. Insco

Theses and Dissertations (ETD)

Background: Sepsis is a condition that can be very costly and very deadly. Diagnosing sepsis can be challenging as there is not one specific test that will identify whether a patient has sepsis and there are varying opinions as to the true definition of sepsis. The definition of sepsis used for this research is a combination of System Inflammatory Response Syndrome (SIRS) with an identified infection. Medical Coders must review the documentation provided in a medical record to accurately assign an ICD-10-CM code. Administrative data is then used to provide statistical information for research purposes. When coded data is not …

Cellular Dynamics And Disease Outcome Of Type 3 Streptococcus Pneumoniae Clinical Isolates Differ Between Strains, Taylor Rae Plunkett White

Theses and Dissertations (ETD)

Streptococcus pneumoniae is a bacterial pathogen that continues to be a major cause of disease around the world. It is not only the number one cause of bacterial pneumonia but also the cause of about 15% of the deaths of children under 5 around the world. There is a lot of research done on this organism, but with around 100 known serotypes and each one producing a unique capsule, there is still much more to be studied. The Etiology of Pneumonia in the Community (EPIC) study conducted by the CDC observed the burden of hospitalizations caused by pneumonia while determining …

Antibiotic Tolerance And Heteroresistance: Associated Fitness Costs And Potential In Evading Antibiotic Killing, Tina H. Dao

Theses and Dissertations (ETD)

Streptococcus pneumoniae is a prominent human pathogen that causes both invasive and non-invasive diseases, such as otitis media, pneumonia, meningitis, and bacteremia. Although it is frequently an asymptomatic colonizer of the human nasopharynx, S. pneumoniae is a major cause of morbidity and mortality in the immune compromised population, young children, and the elderly. Up until the 1970s, S. pneumoniae was susceptible to almost all antibiotics. Since then, this pathogen has gained resistance to a variety of antibiotic treatments, including beta-lactams, macrolides, and fluoroquinolones.

In the first chapter, we focused on fluoroquinolone resistance in S. pneumoniae. Fluoroquinolones are one of the …

Identification Of Effectors Of Synergistic Lethality In Candida Albicans-Staphylococcus Aureus Polymicrobial Intra-Abdominal Infection, Olivia Adele Todd

Theses and Dissertations (ETD)

Candida albicans, an opportunistic fungal pathogen, and Staphylococcus aureus, a ubiquitous pathogenic bacterium, are among the most prevalent causes of nosocomial infections and cause severe morbidity and mortality. Moreover, they are frequently coisolated from central venous catheters and deep-seated infections, including intra-abdominal sepsis. Relatively little is known about the complex interactions and signaling events that occur between microbes and even less so how microbial “cross-talk” shapes human health and disease.

Using a murine model of polymicrobial intra-abdominal infection (IAI), we have previously shown that coinfection with C. albicans and S. aureus leads to synergistic lethality whereas monomicrobial infection is nonlethal. …

Delineating The Upc2a Regulon In Candida Glabrata, Yu Li

Theses and Dissertations (ETD)

Candida glabrata is the second most common cause of invasive candidiasis. Intrinsic resistance has greatly limited the utility of the triazole antifungal, fluconazole, in the treatment of invasive fungal infection. The transcription factor Upc2 regulates the expression of sterol biosynthesis genes in yeast. Disrupting UPC2A in C. glabrata greatly increases its susceptibility to fluconazole (FLU) in both FLU-susceptible and -resistant clinical isolates. Therefore, the Upc2A and its target genes represent a potential pathway for overcoming FLU resistance in C. glabrata. We aimed to delineate the Upc2A regulon to determine its target genes involved in FLU resistance. Transcriptome sequencing (RNA-seq) analysis …

Model-Based Dose-Exposure-Response Assessment For Lead And Backup Spectinamide In A Mouse Model Of Tuberculosis, Santosh Janardan Wagh

Theses and Dissertations (ETD)

Despite decades of research, tuberculosis remains the oldest pathogen-based disease that is the leading cause of death from a single infectious agent. Among many anti-tubercular therapies under investigation, the semisynthetic compounds spectinamides are a promising novel class of anti-tuberculosis agents. One such lead candidate, spectinamide 1810, and backup spectinamide 1599 have demonstrated excellent efficacy, safety, and drug-like properties in various in vitro and in vivo assessments. The dose-ranging and dose fractionation studies were designed to characterize the dose-exposure-response relationship for lead and backup spectinamide in a mouse model of Mycobacterium tuberculosis infection. In this current study, we used 26 and …

Role Of Cerebral Vasculature And Effect Of Circulating Exosomes In Propagation Of Systemic Inflammatory Responses Into The Central Nervous System, Mahesh Chandra Kodali

Theses and Dissertations (ETD)

Sepsis-associated encephalopathy (SAE) is an acutely progressing brain dysfunction induced by systemic inflammation. The mechanism of initiation of neuroinflammation during SAE, which ultimately leads to delirium and cognitive dysfunction, remains elusive. The goal of this project was to study the molecular events of SAE to capture its onset and progression into the central nervous system (CNS), and further identify the cellular players involved in mediating acute inflammatory signaling. Gene expression profiling on the cerebral vessels isolated from the brains of the mice treated with peripheral lipopolysaccharide (LPS) revealed that the cerebral vasculature responds within minutes to acute systemic inflammation by …

Validation And Application Of A Novel Target-Based Whole-Cell Screen To Identify Antifungal Compounds, Christian Alexander Dejarnette

Theses and Dissertations (ETD)

Traditional approaches to drug discovery are inefficient and have several key limitations that constrain our capacity to rapidly identify and develop novel experimental therapeutics. To address this, we have devised a second-generation target-based whole-cell screening assay based on the principles of competitive fitness, which can rapidly identify target-specific and physiologically-active compounds. Briefly, strains expressing high, intermediate, and low levels of a preselected target protein were constructed, tagged with spectrally distinct fluorescent proteins (FPs), and mixed together. The pooled strains were then grown in the presence of various small molecules, and the relative growth of each strain within the mixed culture …

Novel Determinants That Influence Azole Susceptibility In Candida Glabrata And Candida Albicans, Sarah Garland Whaley

Theses and Dissertations (ETD)

Despite the scientific and medical communities’ best efforts, the incidence of fungal infections in susceptible populations continues to rise. The most common cause of these opportunistic fungal infections is Candida. In fact, Candida is the fourth most common pathogen associated with nosocomial blood stream infections. Reported mortality rates for patients with candidemia vary, but have not decreased in the past fifteen years and are reported to be as high as 50%. Candida glabrata, second only to Candida albicans among Candida infections, expresses high rates of resistance to treatment with arguably the best class of currently available antifungals - …

Development Of Oral Vaccines Against Lyme Disease, Rita Raquel Dos Anjos De Carvalho E Melo

Theses and Dissertations (ETD)

Lyme Disease, caused by the spirochete Borrelia burgdorferi, is the most common vector-borne disease in the United States and Europe. If left untreated, it can lead to permanent damage to the nervous and musculoskeletal systems. In some cases, patients that receive the recommended antibiotic therapy develop a debilitating health condition associated with substantial health care costs. Despite current preventive measures, the incidence and the geographic distribution of Lyme Disease continues to increase. Recent estimates from CDC suggest that the true number of cases of Lyme Disease in the US is approximately 300,000 per year. Yet, there is currently no vaccine …

Genetic Control Of Survival And Weight Loss During Pneumonic Burkholderia Pseudomallei (Bp) Infection, Felicia D. Emery

Theses and Dissertations (ETD)

Burkholderia pseudomallei (Bp) is a saprophytic, gram-negative aerobe and the causative agent of the disease melioidosis. Melioidosis is an infectious disease that occurs in humans and animals and is prevalent in Southeast Asia, northern Australia and other tropical areas. Transmission occurs through direct contact with the organism via ingestion, inhalation, or through open wounds and skin abrasions. Clinical presentation is extremely variable and can range from acute septicemia with bacterial dissemination to distant sites, to an isolated pulmonary infection. Treatment of melioidosis can be problematic because it is often difficult to diagnose and Bp is resistant to a diverse group …

Development And Evaluation Of Amphotericin B Loaded Iron Oxide Nanoparticles For Targeted Drug Delivery To Systemic Fungal Infections, Pavan Balabathula

Theses and Dissertations (ETD)

A targeted nanotheronostic drug delivery system to diagnose and treat life threatening invasive fungal infections (IFIs) such as cryptococcal meningitis was designed, developed, characterized, and evaluated. To address the development processes, first, iron oxide nanoparticles (IONP) (34-40 nm) coated with bovine serum albumin (BSA), loaded and targeted with amphotericin B (AMB) (AMB-IONP) was formulated by applying a layer by layer approach. Several designs (A, B, C, D, & E) of AMB-IONP were developed and their physicochemical properties such as drug loading with HPLC method, particle size, poly dispersity index (PDI), and ζ-potential using dynamic light scattering (DLS) technique, morphology with …

A Novel Mechanism Of Enhanced Susceptibility To Bacterial Pneumonia In Influenza-Infected Hosts, Hazem Elsayed Ghoneim

Theses and Dissertations (ETD)

Viruses such as influenza suppress host immune function by a variety of methods. This may result in a significant morbidity through several pathways, including facilitation of secondary bacterial pneumonia from pathogens such as Streptococcus pneumoniae. Lungresident alveolar macrophages (AMs) act as the first line of innate cellular immunity against respiratory bacterial pathogens, including pneumococcus. Therefore, they represent an attractive target for study Before investigating the impact of influenza infection on resident AMs, we first characterized different subsets of lung-resident macrophages in naïve mice using a novel in vivo labeling approach in conjunction with multicolor flow cytometric analysis and confocal microscopic …

Erg11-Mediated Azole Resistance In Candida Albicans, Stephanie Ann Flowers

Theses and Dissertations (ETD)

Although many medically important Candida species are commensal to the gut or colonizers of the skin, these organisms have the propensity to cause disease in the event of a waning immune system. Clinical manifestations of infections with Candida species can range from superficial mucosal infections to deep organ involvement usually resulting from haematogenous spread of infection. Despite significant progress made in the management of patients with fungal infections, the emergence of antifungal resistant clinical isolates creates significant problem in regards to antifungal prophylaxis and empirical treatment strategies. Antifungal resistance is associated with high mortality rates and hefty medical costs. The …

Signal Transduction And Transcriptional Regulation Pathways Essential For Azole Resistance In Candida Albicans, Erin M. Vasicek

Theses and Dissertations (ETD)

Candida albicans is the most prevalent human fungal pathogen, found as a commensal organism in the mucosa, gastrointestinal, and urogenital tracts of humans. This pathogenic fungus causes a wide spectrum of diseases, including the mucosal infection oropharyngeal candidiasis (OPC) which frequently effects patients with human immunodeficiency virus (HIV). The azole antifungals (such as fluconazole) are the most widely used and important ergosterol biosynthesis inhibitors (EBIs) for the treatment of Candida infections, including OPC. However, the azoles are fungistatic against C. albicans and therefore have limited efficacy against this organism, especially for immunocompromised patients. In C. albicans, the transcription factor Upc2 …

Toll-Like Receptors 2 And 9 Are Important For Innate Immune Cell Activation And Recruitment In Hypersensitivity Pneumonitis, Kelly J. Andrews

Theses and Dissertations (ETD)

Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by repeated inhalation of environmental antigens. The disease is characterized by alveolitis and granuloma formation; however, some patients develop chronic HP (CHP), a restrictive lung disease characterized by fibrosis. Previous studies revealed that neutrophils are recruited into the lung via a MyD88- dependent pathway and regulate disease severity through cytokine production. Toll-like receptors (TLRs) 2 and 9 recognize conserved molecular patterns present in bacteria, and signal through the adaptor molecule MyD88. The goal of my project is to investigate the role of TLRs 2 and 9 in the pathogenesis of HP …

Pharmacokinetic And Pharmacodynamic Studies Of A Novel Spectinamide Series Of Antituberculosis Agents, V. N. R. Pavan Kumar Vaddady

Theses and Dissertations (ETD)

Spectinamides are novel amide derivatives of the antibiotic spectinomycin that have emerged as a new class of agents to treat tuberculosis. These agents showed potent in vitro activity against Mycobacterium tuberculosis (MTB) compared to spectinomycin and in a preliminary in vivo study in interferon gamma (IFN‑γ) knockout mice, spectinamide Lee1329 reduced the lung bacillary load of TB comparable to streptomycin. We hypothesized that the application of an iterative pharmacokinetics and pharmacodynamics (PK/PD) guided approach would facilitate the optimization of these lead compounds suitable for further development.

A series of in vitro experiments including parallel artificial membrane permeability assay (PAMPA), microsomal …

Inflammatory Proteins, Genetic Variation, And Environmental Influences On Health Care Associated Infection Development In Sepsis, Reba Antoinette Umberger

Theses and Dissertations (ETD)

The purpose of this study was to determine the impact of baseline systemic inflammation (pro‑inflammatory cytokine, anti‑inflammatory cytokine, and their ratio), genetic variability, and environment on the development of health care associated infections (HAI) among sepsis patients during their ICU stay (up to 28 days).

Methods: A prospective observation study was conducted at the Veterans Affairs Medical Center in the Medical Intensive Care Unit over an 18 month period. A total of 78 patients were enrolled within 72 hours of presenting to the ICU with sepsis. Patient were excluded if they were receiving immunosuppressants (chemotherapy or greater than one mg/kg …

Interactions Of Francisella Tularensis With Components Of The Host Fibrinolytic System, Shawn Russell Clinton

Theses and Dissertations (ETD)

Francisella tularensis (FT) is a Gram-negative coccobacillus and causative agent of a life-threatening disease commonly referred to as tularemia. Due to the highly infectious nature of the organism, its previous development as a biowarfare agent and its potential use in acts of bioterrorism, this bacterium is listed as a Category A select agent by the Centers for Disease Control and Prevention (CDC). Efforts to understand the pathogenic mechanisms of FT within the host environment are vital for the development of safe and effective vaccines, as well as treatments, against tularemia. Though considered an intracellular pathogen, FT research of late has …

Transcriptional Regulation Of Azole Antifungal Resistance And Tolerance In Candida Glabrata, Kelly E. Caudle

Theses and Dissertations (ETD)

Azole antifungal resistance has emerged as a significant problem in the management of infections caused by fungi including Candida species. In recent years, Candida glabrata has become the second most common cause of mucosal and invasive fungal infections in humans second to Candida albicans. Not only are systemic C. glabrata infections characterized by high mortality rates, treatment failures to the azole class of antifungals, the most widely used antifungal for treatment of Candida infections, have been reported. Contributing to this problem, C. glabrata exhibits intrinsic reduced susceptibility to the azole antifungals, and the development of high-level azole resistance …

Transcriptional Regulation Of Azole Antifungal Resistance In Candida Albicans, Teresa T. Liu

Theses and Dissertations (ETD)

Candida albicans is a pathogenic fungi found in the mucosa, gastrointestinal, and urogenital tracts of humans. Oropharyngeal candidiasis (OPC), an opportunistic mucosal infection caused by C. albicans, occurs most frequently in patients infected with human immunodeficiency virus (HIV). OPC is usually treated with azole antifungals, a class of antifungals that target ergosterol biosynthesis, at low doses over long periods of time. This course of treatment allows for the development of azole resistance.

Two major mechanisms of azole resistance exist in C. albicans, the up-regulation of genes encoding efflux pumps and the up-regulation of ERG11, a gene encoding the azole drug …

Biochemical And Immunological Mechanisms Underlying Differential Interaction Of Superantigens With Host Immunogenetic Factors In Streptococcal Sepsis, Mohammed Nooh

Theses and Dissertations (ETD)

Group A streptococci (GAS) are serious human pathogens that can cause a wide array of diseases ranging from pharyngitis to streptococcal toxic shock (STSS), which is caused by excessive cytokines responses triggered by streptococcal superantigens (Strep SAgs). SAgs interact simultaneously with HLA class II molecules on antigen presenting cells (APC) and with the T cell receptor beta chain variable elements (TCR V) and cause excessive stimulation of both cell types and massive release of inflammatory mediators.

The Strep SAgs include the streptococcal pyrogenic exotoxins (Spes), which play a crucial role in the pathogenesis of severe invasive streptococcal diseases, including Strep …