Pathogenic Microbiology Commons^™

Tetrodotoxin, Fungal Pathogen Infection, And Bacterial Microbiome Associations Are Variable In The Skin Microecosystems Of Two Taricha Newt Species, Talon B. Jost

EWU Masters Thesis Collection

Chytridiomycosis is an amphibian disease linked to population declines and species extinctions, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). While chytridiomycosis can result in host death, some amphibians are less susceptible to severe infections through intrinsic factors including host-associated skin microbes aiding defense through resource competition and antifungal metabolite production. Amphibians can also release toxins in response to stress cues to defend against disease, parasitism, and predation. Tetrodotoxin (TTX) is a potent low molecular weight neurotoxin found in genus Taricha, and despite a previously observed negative relationship between differential levels of TTX concentration and Bd infection presence within a …

Host-Defense Piscidin Peptides As Antibiotic Adjuvants Against Clostridioides Difficile, Adenrele Oludiran, Areej Malik, Andriana C. Zourou, Yonghan Wu, Steven P. Gross, Albert Siryapon, Asia Poudel, Kwincy Alleyne, Savion Adams, David S. Courson, Myriam L. Cotten, Erin B. Purcell

Chemistry & Biochemistry Faculty Publications

The spore-forming intestinal pathogen Clostridioides difficile causes multidrug resistant infection with a high rate of recurrence after treatment. Piscidins 1 (p1) and 3 (p3), cationic host defense peptides with micromolar cytotoxicity against C. difficile, sensitize C. difficile to clinically relevant antibiotics tested at sublethal concentrations. Both peptides bind to Cu²⁺ using an amino terminal copper and nickel binding motif. Here, we investigate the two peptides in the apo and holo states as antibiotic adjuvants against an epidemic strain of C. difficile. We find that the presence of the peptides leads to lower doses of …

Genetic And Biochemical Analysis Of Novel Borrelia Burgdorferi Genes Bb0244 And Bb0246, Christian J. Ruiz-Rodriguez

Honors Undergraduate Theses

As the cause of the most common vector-borne disease in the US, Borrelia burgdorferi continues to affect an estimated hundreds of thousands of patients each year. The spirochete boasts one of the most complex genomes in comparison to all other prokaryotes as it is fragmented across up to 21 different replicons. Moreover, the functions of a majority of the encoded genes remain unknown. Gene of unknown function, bb0244, along with putative co-transcribed genes bb0245, and bb0246 are hypothesized to be involved in the vital functions of cell division and cell wall biogenesis. B. burgdorferi lacking bb0244 demonstrate a significant growth …

Invasion Of Superbugs: Cockroach-Driven Outbreak Of Multidrug-Resistant Enterobacter In An Icu, Jennifer Hanrahan, Nicholas Schouten, Steven H. Fyffe, Annette Jencson, Stephanie Stroever

Department of Medicine Faculty Publications

Objective: To describe factors in an outbreak of multidrug-resistant Enterobacter cloacae (MRE) in an intensive care unit (ICU) over a 20-month period including the likely contribution of cockroaches to the outbreak.

Design: This is a retrospective descriptive study.

Setting: ICU in an urban hospital.

Patients: All patients admitted to the ICU during the 20-month outbreak period were included in the study.

Interventions: Infection prevention interventions included contact isolation, hand hygiene, dedicated patient equipment, environmental cultures, and pest control.

Results: 25 patients were identified as being colonized or infected with MRE. Relatedness of the outbreak strain and strains found in cockroaches …

Salmonella Detection In Food Using A Hek-Htlr5 Reported Cell-Based Sensor, Esma Eser, Victoria A. Felton, Rishi Drolia, Arun K. Bhunia

Biological Sciences Faculty Publications

The development of a rapid, sensitive, specific method for detecting foodborne pathogens is paramount for supplying safe food to enhance public health safety. Despite the significant improvement in pathogen detection methods, key issues are still associated with rapid methods, such as distinguishing living cells from dead, the pathogenic potential or health risk of the analyte at the time of consumption, the detection limit, and the sample-to-result. Mammalian cell-based assays analyze pathogens’ interaction with host cells and are responsive only to live pathogens or active toxins. In this study, a human embryonic kidney (HEK293) cell line expressing Toll-Like Receptor 5 (TLR-5) …

Erwinia Amylovora Phage Therapy: Biocontrol Formulation, Receptor Identification, Resistance Mechanisms, Nassereldin Ibrahim

Theses and Dissertations (Comprehensive)

Fire blight is known as a disease of Rosaceae and it displays infection symptoms in about 200 species in 40 rosaceous genera. The most economically important crops that are affected by fire blight are apples and pears. Fire blight can cause severe outbreaks and a single fire blight outbreak can disrupt orchard production for years. The bacterium that causes this disease is indigenous in North America, and according to Statistics Canada, economic losses in apples and pears were valued at an estimated $4 million in 2005, which is approximately 5% of the total production. In addition, production costs can increase …

Synergetic Signaling Between The Chlamydia Secreted Effectors Tarp And Tmea Regulates Actin Kinetics And Efficient Entry, Matthew Romero

Theses & Dissertations

Chlamydia trachomatis is both the leading cause of non-congenital preventable blindness in developing nations and the leading source of bacterial sexually transmitted infections. As an obligate intracellular pathogen, Chlamydia has an absolute requirement on gaining entry into its host, which is accomplished by manipulating the host actin cytoskeleton to assemble engulfment structures that drive pathogen entry. In support of this, Chlamydia secretes the effectors TarP and TmeA via a type-III secretion system, whose respective signaling outputs operate synergistically to generate rapid actin kinetics and efficient pathogen engulfment. Rapid actin recruitment characteristic of invading Chlamydia is derived from a collaborative interaction …

Pathogenicity Of Acinetobacter Calcoaceticus, Kaitlan A. Sullivan

MUSC Theses and Dissertations

Acinetobacter is a genus of gram-negative bacteria that have been appearing frequently in hospitals contributing to infections in the blood, lungs, urinary tract, and other parts of the body. It infects patients with weakened immune systems that are placed on ventilators, after the use of catheters, or have any other open wounds produced by prolonged hospital stays. This genus of bacteria is problematic due to its high probability of becoming resistant to multiple classes of antibiotics. Thus, we are determining the pathogenicity of clinical isolates of Acinetobacter calcoaceticus using the organism Caenorhabditis elegans as a model.

We are testing …

Identification And Characterization Of Geotrichum Candidum Isolates From Peach With Reduced Sensitivity To Propiconazole, Sara Price

All Theses

Geotrichum candidum Link (1809) is a yeast-like fungus that causes sour rot of stone fruits, including peach (Prunus persica). The disease caused damage between 2021 and 2023 to the peach crop kept in cold storage at a commercial farm in South Carolina despite preharvest and postharvest applications of fungicides. Isolates from 41 symptomatic fruit, from a South Carolina (SC) commercial packing house, as well as other isolates obtained from South Carolina were identified to be G. candidum based on species-specific PCR amplifications of the β tubulin gene. Commonly used postharvest fungicide fludioxonil had no effect on G. candidum mycelial growth …

Breaking Virulent: The Coincidental Evolution Of Virulence Factors In Bacteria., Rhiannon Emmanuelle Cecil

Electronic Theses and Dissertations

Understanding how innocuous organisms can evolve to be pathogenic to humans is of increasing global concern. Further, understanding how existing pathogens may evolved to be more virulent is also vital to our ability to provide healthcare to people afflicted with diseases that promote chronic bacterial infections, such as cystic fibrosis. With the rise of antibiotic resistance in both bacteria and fungi it is paramount that new therapeutics are identified. Understanding what mutations occur that result in increased virulence in microbes can potentially provide new targets for antimicrobial drugs to combat antibiotic resistance. The Coincidental Evolution Hypothesis is a fundamental hypothesis …

Characterizing The Regulation Of Candida Albicans Hyphal Morphogenesis In The Context Of Host Macrophages, Hannah Wilson

Dissertations and Theses (Open Access)

Candida albicans is a commensal fungus that resides on the skin, mucosal surfaces, and in the gut of an estimated 80% of individuals. Though generally harmless, C. albicans is capable of causing uncomfortable mucosal infections as well as deadly disseminated infections depending on the immune status of the host. Although antifungal therapeutics exist, the mortality rate associated with disseminated disease still lingers around 50%. Further, C. albicans is the fourth most common cause of all bloodstream infections and continues to present as a major clinical issue with less than satisfactory treatment options. For this reason, it is imperative to understand …

Connecting The Nebraska Water Quality Index To The Aquatic Microbial Community Of The North Platte River Basin, Nebraska, Paula R. Guastello

School of Natural Resources: Dissertations, Theses, and Student Research

The Nebraska Water Quality Index, under development by the Nebraska Department of Environment and Energy, summarizes in a single value eight environmental parameters that have been monitored in Nebraska for nearly 20 years. Water quality parameters including those used in the Nebraska Water Quality Index have been shown in previous studies to impact bacterial growth. As such, this index has the potential to correlate with the freshwater microbial community. Here, I relate the Nebraska Water Quality Index to microbial community composition and structure using 16S rRNA gene amplicon sequence data collected from the North Platte River Basin, Nebraska. This index …

Persistence Of Salmonella Enterica Subsp. Enterica Ser. Javiana, Listeria Monocytogenes, And Listeria Innocua In Hydroponic Nutrient Solution, Gayatri R. Dhulappanavar, Kristen E. Gibson

Food Science Faculty Publications and Presentations

This study aimed to determine the persistence of Salmonella Javiana, Listeria monocytogenes, and Listeria innocua in nonsterile, hydroponic nutrient solution (NS) at 15, 25, 30, and 37°C over a 21-day period to mimic time from seedling to mature lettuce. Bacteria were inoculated in modified Hoagland's NS at 106 CFU/mL and maintained at 15, 25, 30, and 37°C. Samples were collected at various time points, and bacteria were quantified. A mixed model was used to determine the effect of bacteria type, time (day), and temperature on bacteria concentration (log CFU/mL). The least-squares means were calculated to compare the mean log …

Molecular Mimicry Of Noda Genes By An N-Acetylmuramoyl-L-Alanine Amidases Gene In A Nodule Forming Staphylococcus Cohnii [Research Note], Aberathne Herath Mudiyanselage Nadeeshani Ruwandika Aberathne, Wedage Methsala Madurangi Wedage, Dilantha Gunawardana

The Philippine Agricultural Scientist

A rare, nodule-forming, Gram-positive bacterium (Sub4) was isolated from the forage and cover crop Pueraria phaseoloides, which aligned at 99.26% sequence identity to a partial 16S rDNA sequence of Staphylococcus cohnii sp. This was the first record of a strain/species of Staphylococcus capable of independent, unassisted nodule formation in a legume host. When a nodA gene was sought by PCR using a pair of gene-specific primers synthesized using a related (Firmicutes) Paenibacillus sp. nodA gene, the reaction yielded a PCR product of similar size but a distinct identity. The resulting ~400bp PCR product coded for a likely N-acetylmuramoyl-L-alanine amidase …

The Bactericidal Activity Of A Novel Aneurinibacillus Aneurinilyticus Isolate Effectively Controls Foodborne Pathogens Campylobacter Jejuni And Listeria Monocytogenes, Peter M. Rubinelli, Rohana Liyanage, Jackson Lay, Jennifer C. Acuff

Chemistry & Biochemistry Faculty Publications and Presentations

Human zoonotic infection with Campylobacter is a major cause of gastroenteritis in the United States and worldwide. Listeria monocytogenes causes a potentially fatal infection in humans and is often attributed to contaminated food. Genetic typing has demonstrated that Campylobacter infection is often associated with the consumption of contaminated poultry products, with Campylobacter often colonizing the poultry gastrointestinal tract, while listeriosis is commonly associated with the consumption of contaminated ready-to-eat (RTE) foods. In this study, a strain of endospore-forming bacterium (strain NH) that is bactericidal towards the human food pathogens Campylobacter jejuni and Listeria monocytogenes was identified and characterized. Transwell experiments …

Evaluation Of The Virulence Potential Of Avian Pathogenic Escherichia Coli Isolated From Broiler Breeders With Colibacillosis In Mississippi, Jiddu Joseph

Theses and Dissertations

Avian pathogenic Escherichia coli (APEC) is a bacterium that is responsible for colibacillosis in birds. However, information about broiler breeder APEC isolates is limited, but the data is critical due to the transfer of this bacteria down the production pyramid to progenies resulting in high mortality. Therefore, we evaluated the phenotypic virulence characteristics of 28 isolates using embryo lethality and day-old chick challenge assays. Also, the in vitro adhesion and invasion potential of selected nine isolates were identified. Results showed more than 1/3^rd of the isolates were highly virulent and the virulence increased as the number of virulence-associated genes …

Glycerophosphocholine Is Used For Lipid And Phosphate Metabolism By Candida Albicans, Will King

Electronic Theses and Dissertations

The metabolism of phosphatidylcholine (PC), a major eukaryotic membrane lipid, has been shown to be an important aspect of pathogenesis in Candida albicans. Of note, PC turnover product, glycerophosphocholine (GPC), is abundant renal metabolite available within the host. GPC is readily imported by C. albicans, and deletion of the major GPC transporter, Git3, leads to decreased virulence in a bloodstream infection model. Here I have characterized two potential metabolic fates of internalized GPC. The first metabolic fate explored is internalized GPC can be hydrolyzed to release P_i. To determine if GPC import and subsequent metabolism impact phosphate …

Use Of Transposon Screening For Salicylic Acid-Assisted Desiccation Killing In Salmonella, Shannon D. Elliott

Electronic Theses and Dissertations

Salmonella enterica serovar Typhimurium is one of the most prevalent food-borne pathogens, affecting millions around the world every year, making it a threat to global health. Salmonella possesses the ability to survive the normally lethal condition of desiccation, however, discovery of the genes and mechanisms behind this phenomenon are still ongoing. Using a transposon mutagenesis approach to construct a broad transposon library, this study aimed to uncover genes that may be contributing to changes in Salmonella’s survivability under desiccation, particularly when exposed to the antimicrobial molecule salicylic acid. Building on previous findings showing salicylic acid can alter cell viability …

Elucidating Acetate Metabolism: Identification Of Transporters And Enzymes Required For Acetate Utilization In The Fungal Pathogen Cryptococcus Neoformans, Perry L. Kezh

All Dissertations

Cryptococcus neoformans is the leading cause of fungal meningitis world-wide. While exposure to this environmental sporophyte is common during childhood, those who are immune compromised are at risk of infection. Following inhalation, this basidiomycetous fungus subsequently colonizes other organs though hematogenous dissemination, eventually crossing the blood brain barrier and colonizing the brain where it causes as cryptococcal meningitis. Changes in the availability of carbon sources stemming from the movement from soil to the lungs induce changes in fungal metabolism. Specifically, alveolar macrophages, which present a first line of defense against infection, provide a glucose-/amino acid-poor environment. As such, the use …

Effect Of Authentic Kefir And Nigella Sativa On Broilers Challenged By Coccidia And Clostridium Perfringens, Julian E. Nixon

All Dissertations

Black seed oil concentrations of 0%, 0.1%, 1% and 5% were added to milk inoculated with kefir grains and incubated at 25°C for 22 h. The pH and microbial count indicated 1% black seed oil caused low inhibition (P > 0.05) of fermentation, but 5% black seed oil caused significant inhibition of the kefir microorganisms (P < 0.05).

Cobb 500 male chicks (n = 256) were distributed in a randomized block design and received one of four treatments: CTRL1 (Non-medicated, no kefir, no Clostridium perfringens), CTRL2 (Non-medicated, no kefir, C. perfringens inoculated), CTRL3 (BMD medicated, no kefir, C. perfringens inoculated), KTRT (Non-medicated, …