Medical Microbiology Commons^™

Infection And Transmission Determinants Of Flea-Borne Rickettsioses, Hanna J. Laukaitis

Graduate Theses and Dissertations (2019 - present)

The genus Rickettsia is comprised of Gram-negative, obligate intracellular bacteria that are spread by hematophagous arthropods. Elucidating the factors conferring rickettsial virulence has perplexed investigators for decades, complicated by the lack of efficient genetic tools necessary to uncover rickettsial- and vector-specific factors contributing to persistence. The advent of transposon mutagenesis has enabled the field to make vast developments in uncovering novel rickettsial mechanisms utilized in various host backgrounds. Thus, the aim of this study was to generate Rickettsia felis transposon mutants and characterize novel phenotypes associated with genetic disruption in an arthropod background. Distribution of rickettsiae is reliant on the …

Effect Of Sub-Inhibitory Concentrations Of Nitrofurantoin, Ciprofloxacin And Trimethoprim On In-Vitro Biofilm Formation In Uropathogenic Escherichia Coli, Shane Whelan

ORBioM (Open Research BioSciences Meeting)

The purpose of the current study was to determine the effect of sublethal concentrations of nitrofurantoin, ciprofloxacin and trimethoprim on biofilm formation in 57 uropathogenic Escherichia coli strains (UPEC).

The MIC of nitrofurantoin, ciprofloxacin and trimethoprim was determined for 57 UPEC isolates. Biofilm formation for each isolate with and without sub-lethal concentrations of each antibiotic was then quantified, and the statistical significance of changes in biofilm formation was ascertained by way of a Dunnett's test.

The effects of sub-MIC antibiotics on biofilm formation of UPEC were variable. A total of 22.8% of strains were induced to form biofilm by nitrofurantoin, …

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 …

Catheter-Associated Urinary Tract Infections: Patient Characteristics, Treatment, And Clinical Outcomes In One South Texas Acute Care Hospital, Kimberly A. Ambrosini, Jose Campo Maldonado

MEDI 9331 Scholarly Activities Clinical Years

Background: Catheter-associated urinary tract infections (CA-UTIs) account for 40 percent of nosocomial infections worldwide. Their elimination is at the forefront of quality improvement in one South Texas acute care hospital.

Methods: Over a period of 6 months, five CA-UTIs occurred in one South Texas acute care hospital. These cases were identified via regular surveillance by Infection Prevention staff and the Laboratory Department of the hospital. This research reviews patient age, sex, length of stay, bacteria contracted, appropriate antibiotic use, patient characteristics, and overall outcomes.

Results: Between the months of July and December 2021, 5 CAUTIs were contracted. Patients …

Evaluation Of Stratified Antibiograms For Use In Laboratory And Antimicrobial Stewardship, Linsey Donner

Theses & Dissertations

Antibiograms are critical for choosing empiric antimicrobial therapy. Cumulative antibiograms, which aggregate susceptibility data, can mask differences within specific patient subsets or clinical syndromes. This dissertation was done to determine if antibiotic susceptibilities showed substantial differences when comparing stratified antibiograms to cumulative antibiograms.

Antibiotic susceptibility data was retrospectively obtained from Nebraska Medicine January 1, 2017 – December 31, 2019 for Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis. The University of Nebraska Medical Center’s web antibiogram clinical decision support tool was used to export the data. Bacteria-antibiotic susceptibility rates of stratified antibiograms …

Genital Chlamydia Infection Is Influenced By The Female Sex Hormones Estrogen And Progesterone In Vivo, Amy Gail Gravitte

Electronic Theses and Dissertations

Chlamydia is the most common bacterial sexually transmitted infection in the United States and worldwide. It often goes unnoticed due to lack of symptoms and left untreated it can ascend the female genital tract to cause sequelae like pelvic inflammatory disease and irreversible tubal infertility. In reproductive-aged women, female sex hormones estrogen (E2) and progesterone (P4) concentrations fluctuate during the menstrual cycle and are influenced by hormonal contraceptives and hormone replacement therapy. E2 and P4 influence genital Chlamydia infection in women and mice, but these multifactorial interactions are not entirely mapped out. The complex interplay of E2 and P4 with …

Intestinal Dysbiosis – A New Treatment Target In The Prevention Of Colorectal Cancer, Florinela-Andrada Dumitru, Sergiu Ioan Micu, Roxana Emanuela Popoiag, Marilena Musat, Andreea Daniela Caloian, Valentin Calu, Vlad Denis Constantin, Daniela Gabriela Balan, Cornelia Nitipir, Florin Enache

Journal of Mind and Medical Sciences

The gastrointestinal microbiome contains at least 100 trillion microorganisms (bacteria, viruses, fungi), whose distribution varies from the mouth to the rectum spatially and temporally throughout one's lifetime. The microbiome benefits from advancing research due to its major role in human health. Studies indicate that its functions are immunity, metabolic processes and mucosal barrier. The disturbances of these functions, dysbiosis, influence physiology, lead to diabetes, inflammatory bowel disease, obesity and colon tumorigenesis. The third most common form of cancer, colorectal cancer, is the result of many factors and genes, and although the link between dysbiosis and this type of cancer is …

Microbial Influence On Alzheimer's Disease, Ashley N. Hamby

The Cardinal Edge

No abstract provided.

Assesment Of Antibiotic Resistant Gene Expression In Clinical Isolates Of Pseudomonas Aeruginosa, Dustin Esmond

Biology Theses

Increasing prevalence of nosocomial infections by antimicrobial resistant pathogens resulting in higher mortality rates and financial burden is of great concern. Pseudomonas aeruginosa represents one of six highly virulent “ESKAPE” pathogens that exhibit considerable intrinsic drug resistance as well as mechanisms for acquiring further resistance. As many of these mechanisms are regulated through gene expression, we sought to identify regulatory strategies and patterns at play in 23 clinical isolates collected from Baku, Azerbaijan and Tyler, Texas, USA. Real-time quantitative polymerase chain reaction was performed on six gene targets implicated in resistance and contrasted with antibiotic phenotypes. We found AmpC cephalosporinase …

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 …

A Novel Application Of Galleria Mellonella Larvae To Study Pathogenesis Of Rickettsia Rickettsii Infection, Jacob M. Jones

Honors College Theses

Rickettsia are obligate intracellular tick-borne bacteria that cause acute undifferentiated febrile illness accompanied by headache, malaise, myalgias, and disseminated endothelial infection. Immune responses to Rickettsia and pathogenesis of rickettsioses are not fully understood. Current work with Rickettsia is limited to vertebrate models that are strictly regulated and have low throughput. Since the innate immune system of vertebrates retains striking similarities with the immune response in insects, invertebrates are being used to study host responses to various pathogens. The purpose of this study was to evaluate if larvae of the greater wax moth Galleria mellonella (GML) can be used as an …

When The Pandemic Opts For The Lockdown: Secretion System Evolution In The Cholera Bacterium, Francis J. Santoriello, Stefan Pukatzki

Publications and Research

Vibrio cholerae, the causative agent of the diarrheal disease cholera, is a microbe capable of inhabiting two different ecosystems: chitinous surfaces in brackish, estuarine waters and the epithelial lining of the human gastrointestinal tract. V. cholerae defends against competitive microorganisms with a contact-dependent, contractile killing machine called the type VI secretion system (T6SS) in each of these niches. The T6SS resembles an inverted T4 bacteriophage tail and is used to deliver toxic effector proteins into neighboring cells. Pandemic strains of V. cholerae encode a unique set of T6SS effector proteins, which may play a role in pathogenesis or pandemic …

Streptococcus Cristatus – An Oral Bacterium Causing A Case Of Mild Bacteremia And “Possible Endocarditis”, Camilo Guzman, Adi Zaclli, John Molinari

Medical Student Research Symposium

Streptococcus cristatus is a member of the Mitis streptococcus group. Like other members of this group, it resides in mucosal surfaces of the oral cavity but rarely causes disease. We present a case of S. cristatus bacteremia and “possible endocarditis” (per the modified Duke criteria) in a 59-year-old male suffering from end- stage cryptogenic cirrhosis. To date, it is the fifth reported case of disease caused by the microbe, and the first adult case in which S. cristatus was the sole microbe identified. Our patient had a history of dental caries and poor dentition, which were likely the source of …

Comparisons Of Oral, Intestinal, And Pancreatic Bacterial Microbiomes In Patients With Pancreatic Cancer And Other Gastrointestinal Diseases, Mei Chung, Naisi Zhao, Richard Meier, Devin C. Koestler, Guojun Wu, Erika De Castillo, Bruce J. Paster, Kevin Charpentier, Jacques Izard, Karl T. Kelsey, Dominique S. Michaud

Department of Food Science and Technology: Faculty Publications

Background: Oral microbiota is believed to play important roles in systemic diseases, including cancer. Methods: We collected oral samples (tongue, buccal, supragingival, and saliva) and pancreatic tissue or intestinal samples from 52 subjects, and characterized 16S rRNA genes using high-throughput DNA sequencing.

Results: Bray–Curtis plot showed clear separations between bacterial communities in the oral cavity and those in intestinal and pancreatic tissue samples. PERMANOVA tests indicated that bacterial communities from buccal samples were similar to supragingival and saliva samples, and pancreatic duct samples were similar to pancreatic tumor samples, but all other samples were significantly different from each …

Pandemic Vibrio Cholerae Shuts Down Site-Specific Recombination To Retain An Interbacterial Defence Mechanism, Francis J. Santoriello, Lina Michel, Daniel Unterweger, Stefan Pukatzki

Publications and Research

Vibrio cholerae is an aquatic microbe that can be divided into three subtypes: harmless environmental strains, localised pathogenic strains, and pandemic strains causing global cholera outbreaks. Each type has a contact-dependent type VI secretion system (T6SS) that kills neighbouring competitors by translocating unique toxic effector proteins. Pandemic isolates possess identical effectors, indicating that T6SS effectors may affect pandemicity. Here, we show that one of the T6SS gene clusters (Aux3) exists in two states: a mobile, prophage-like element in a small subset of environmental strains, and a truncated Aux3 unique to and conserved in pandemic isolates. Environmental Aux3 can be readily …

Investigating Microbial And Host Factors That Modulate Severity Of Clostridioides Difficile Associated Disease, Armando Lerma

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Clostridioides difficile is recognized as one of the most important pathogens in hospital and community healthcare settings. The clinical outcome of infection of toxigenic C. difficile infection (CDI) ranges from asymptomatic colonization to fulminant pseudomembranous colitis and death. In recent studies, it has been suggested that a high proportion of nosocomial CDI cases are transmitted from asymptomatic carriers which might be acting as infection reservoirs. Understanding what causes the different responses to infection could lead to the development of novel prevention and treatment strategies. Although several explanations have been proposed to explain variations in susceptibility, understanding of the exact mechanisms …

Chain-Selective Isotopic Labeling Of The Heterodimeric Type Iii Secretion Chaperone, Scc4:Scc1, Reveals The Total Structural Rearrangement Of The Chlamydia Trachomatis Bi-Functional Protein, Scc4, Thilini O. Ukwaththage, Samantha M. Keane, Li Shen, Megan A. Macnaughtan

School of Medicine Faculty Publications

Scc4 is an unusual bi-functional protein from Chlamydia trachomatis (CT) that functions as a type III secretion system (T3SS) chaperone and an RNA polymerase (RNAP)-binding protein. Both functions require interactions with protein partners during specific stages of the CT developmental cycle. As a T3SS chaperone, Scc4 binds Scc1 during the late stage of development to form a heterodimer complex, which chaperones the essential virulence effector, CopN. During the early-middle stage of development, Scc4 regulates T3SS gene expression by binding the σ66-containing RNAP holoenzyme. In order to study the structure and association mechanism of the Scc4:Scc1 T3SS chaperone complex using nuclear …

The Inhibitory Effects Of An Antimicrobial Gel On The Staphylococcus Species, Mara Trinkle

Undergraduate Honors Theses

The prevalence of antibiotic resistant bacteria has made the choices for topical treatments for patients who experience burns wounds extremely limited. The Staphylococcus genus is naturally occurring in and on the human body but can become harmful once it enters the bloodstream. A novel antimicrobial gel has been shown by our laboratory to inhibit both the planktonic growth and biofilm formation of Staphylococcus aureus in previous studies. The antimicrobial gel is made of seven natural compounds including antioxidants (vitamin C and E). We wanted to examine the effects of the antimicrobial gel on numerous other Staphylococcal species because it is …

Plasmodium Impairs Antibacterial Innate Immunity To Systemic Infections In Part Through Hemozoin-Bound Bioactive Molecules., Christopher Lynn Harding

Electronic Theses and Dissertations

Despite efforts to decrease the global health burden of malaria, infections with Plasmodium species continue to cause over 200 million episodes of malaria each year which resulted in 405,000 deaths in 2018 [1]. One complication of malaria is increased susceptibility to invasive bacterial infections. Plasmodium infections impair host immunity to non-Typhoid Salmonella (NTS) through activities of heme oxygenase I (HO-I) )-induced release of immature granulocytes and myeloid cell-derived IL-10. Yet, it is not known if these mechanisms are specific to NTS. We show here, that Plasmodium yoelii 17XNL (Py) infected mice had impaired clearance of systemic Listeria monocytogenes (Lm) during …

Gut Pathophysiology In Mouse Models Of Social Behavior Deficits, Kyla Scott

Undergraduate Honors Theses

Autism spectrum disorders (ASD) encompass neurodevelopment disorders characterized by atypical patterns of development that impact multiple areas of functioning beginning in early childhood. The etiology of ASD is unknown and there are currently no preventative treatment options. Gastrointestinal symptoms are commonly associated comorbidities. The microbiota-gut-brain axis is a multidirectional communication chain that connects the central and enteric nervous system that relates brain function to peripheral intestinal functions. Changes within this axis have been postulated in ASD. For example, the “leaky gut theory” proposes that chronic inflammation is linked to alterations in the bacterial profiles of the gut microbiome and subsequent …

Molecular Mechanisms Of Antimicrobial Resistance In Multi-Drug Resistant Enterococci, Ayesha Khan

Dissertations and Theses (Open Access)

Antibiotic resistance is a major global public health threat. Enterococci are recalcitrant, nosocomial pathogens that can be intrinsically resistant to valuable antibiotics, like beta-lactams, or evolve resistance to all existing antimicrobials. The LiaFSR system regulates resistance to cell membrane (CM) stressors like daptomycin (DAP), a front-line drug for multi-drug resistant infections. DAP resistance (DAP-R) in E. faecalis is mediated by CM phospholipid alterations. Emergence of DAP-R often leads to b-lactam resensitization, a phenomenon called the seesaw effect. The molecular mechanism of DAP-R and the seesaw effect are unknown. Here we show that LiaX is a surface exposed protein whose C-terminal …

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

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 …

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 …

Understanding The Host Immune Response Against Pseudomonas Aeruginosa To Develop Novel Therapeutics And Vaccines, Emel Sen Kilic

Graduate Theses, Dissertations, and Problem Reports (ETD)

Pseudomonas aeruginosa is a Gram-negative opportunistic bacterium that causes a broad range of acute and chronic infections. The high adaptability and emergence of multidrug-resistant strains of this bacterium pose a significant threat to human health. Particularly, pneumonia caused by this pathogen is associated with high morbidity and mortality in immunocompromised patients. To prevent these infections, we aimed to develop novel vaccine strategies by characterizing the host immune response against P. aeruginosa. During respiratory infections, P. aeruginosa first contacts with epithelial cells along the respiratory tract. Using RNA-sequencing, we were able to characterize transcriptional changes of the epithelial cells in …

Elucidating Immune Signaling Of Influenza A Virus And Aspergillus Fumigatus Co-Infections Through Pioneered Model Development, Meagan Danyelle Rippee-Brooks

Graduate Theses/Dissertations

Bacterial co-infections with influenza A virus (IAV) are extremely serious and life-threatening. However, there exists limited understanding about the importance of fungal infections with IAV. Clinical case reports indicate that fungal co-infections do occur and suggest the IAV pandemic of 2009 had a propensity to predispose patients to secondary fungal infections more than previous IAV strains. IAV-fungal co-infections are marked by high mortality rates of 47 to 61% in previously healthy individuals between the ages of 20 and 60. Yet, the variables involved in this co-infection remain undetermined. I achieved effective recapitulation of this co-infection using a C57Bl/6 murine (mouse) …

Development Of Improved Acellular Pertussis Vaccines Through Inclusion Of The Rtx Antigen Or Induction Of Mucosal Immunity, Dylan Tyler Boehm

Graduate Theses, Dissertations, and Problem Reports (ETD)

Pertussis is a human respiratory disease, primarily caused by the Gram-negative pathogen Bordetella pertussis. The infection is most severe and can be life-threatening in young children and infants where it manifests as a series of paroxysmal coughs. The disease is more commonly known as whooping cough, due to the whoop omitted during a massive inspiratory effort to bring air back into the lungs. Pertussis is a toxin-mediated disease that persists due to an early release of toxins that allow that bacteria to evade the cells of the innate immune response. The inhibition of the host response continues as toxin activity …

Interfering With Dna Decondensation As A Strategy Against Mycobacteria, Enzo M. Scutigliani, Edwin R. Scholl, Anita E. Grootemaat, Sadhana Khanal, Jakub A. Kochan, Przemek M. Krawczyk, Eric A. Reits, Atefeh Garzan, Huy X. Ngo, Keith D. Green, Sylvie Garneau-Tsodikova, Jan M. Ruijter, Henk A. Van Veen, Nicole N. Van Der Wel

Pharmaceutical Sciences Faculty Publications

Tuberculosis is once again a major global threat, leading to more than 1 million deaths each year. Treatment options for tuberculosis patients are limited, expensive and characterized by severe side effects, especially in the case of multidrug-resistant forms. Uncovering novel vulnerabilities of the pathogen is crucial to generate new therapeutic strategies. Using high resolution microscopy techniques, we discovered one such vulnerability of Mycobacterium tuberculosis. We demonstrate that the DNA of M. tuberculosis can condense under stressful conditions such as starvation and antibiotic treatment. The DNA condensation is reversible and specific for viable bacteria. Based on these observations, we hypothesized …