Pathogenic Microbiology Commons^™

Antibacterial Properties Of Novel Amphiphiles: Exploring Structure-Activity Relationships, Reafa Hossain

Senior Honors Projects, 2010-2019

The increased cases of antibiotic resistance have large implication in hospital settings where infections by antibiotic resistant bacteria are harder to treat resulting in longer stays at the hospital, which drastically increases the costs to patients and hospitals. To address this matter, many research groups are searching for an alternative to antibiotics. One option is the development of amphiphiles, some of which have antibacterial properties. Amphiphiles contain a hydrophilic, polar head group, and a hydrophobic, nonpolar tail, which may intercalate into the cell membrane, resulting in cell lysis. Understanding the impact of amphiphile geometry on antibacterial activity allows for the …

Francisella Tularensis Insertion Sequence Elements Contribute To Differential Gene Expression, Amanda M. Bartling

Theses & Dissertations

This abstract is under embargo until April 26, 2020.

Identification Of Genes Conferring Acid Resistance In Vibrio Parahaemolyticus, Erin Gibbons

Honors Scholar Theses

Vibrio parahaemolyticus has the capability to be acid resistant due to known and unknown mechanisms. The goal of this project was to determine possible genes involved in conferring acid resistance of this bacterium. The vp1277 gene (designated as HA) and its downstream gene vp1999 were investigated for their role in acid resistance. Another potential gene that could contribute to acid resistance is vp0820 because of its similarity to the ToxR gene in Vibrio cholera. All three of these knockout strains and the wild type were grown in neutral LB and then tested with acidic LB’s of pH 4.5, 5, and …

Downregulation Of Microrna Eca-Mir-128 In Seminal Exosomes And Enhanced Expression Of Cxcl16 In The Stallion Reproductive Tract Are Associated With Long-Term Persistence Of Equine Arteritis Virus, Mariano Carossino, Pouya Dini, Theodore S. Kalbfleisch, Alan T. Loynachan, Igor F. Canisso, Kathleen M. Shuck, Peter J. Timoney, R. Frank Cook, Udeni B. R. Balasuriya

Maxwell H. Gluck Equine Research Center Faculty Publications

Equine arteritis virus (EAV) can establish long-term persistent infection in the reproductive tract of stallions and is shed in the semen. Previous studies showed that long-term persistence is associated with a specific allele of the CXCL16 gene (CXCL16S) and that persistent infection is maintained despite the presence of a local inflammatory and humoral and mucosal antibody responses. In this study, we demonstrated that equine seminal exosomes (SEs) are enriched in a small subset of microRNAs (miRNAs). Most importantly, we demonstrated that long-term EAV persistence is associated with the downregulation of an SE-associated miRNA (eca-mir-128) and with an enhanced …

The Characterization Of The Transcription Factor Msab And Its Role In Staphylococcal Virulence, Justin Batte

Dissertations

Staphylococcus aureus is a common human pathogen that is responsible for a wide range of infections, ranging from relative minor skin infections to life-threatening disease such as bacteremia, septicemia, and endocarditis. S. aureus possesses many different virulent factors that aid in its ability to cause this wide array of infections. One major virulence factor includes the production of capsular polysaccharide (CP). The production of CP plays a major role in the virulence response during infection specifically by providing S. aureus an antiphagocytic mechanism that allows the pathogen to evade phagocytosis during an infection. S. aureus has developed complex genetic regulatory …

Characterizing The Virulence Factor Yape In Yersinia Pestis., Tiva Templeton Vancleave

Electronic Theses and Dissertations

Yersinia pestis is the causative agent of bubonic plague and is primarily transmitted by fleas. Upon infection, the bacteria rapidly travel to the regional lymph nodes causing inflammation and cellulitis in these tissues (referred to as buboes). Two outer membrane proteins, YapE and Pla, have been implicated to have roles in dissemination to the lymph nodes. Their adhesive properties have shown that they are able to interact with host macrophages thereby increasing their ability to disseminate to regional lymph nodes. More recently, we have shown that YapE is cleaved by another virulence factor important for lymph node colonization, Pla, to …

Characterization Of Type Ii Toxin Anti-Toxin Systems In Aggregatibacter Actinomycetemcomitans., Blair W. Schneider

Electronic Theses and Dissertations

Microbes express many protective mechanisms in response to environmental stress. Toxin/anti-toxin systems encode a biologically active toxin and a labile anti-toxin that inhibits the toxin’s activity. These systems are known to contribute to persister cell and biofilm formation. A. actinomycetemcomitans thrives in the complex oral microbial community and is subjected to continual environmental flux. Little is known regarding the presence and function of TA systems in this organism or their contribution survival in the oral environment. Using BLAST searches and other informatics tools, we identified 11 intact TA systems that are conserved across all seven serotypes of A. actinomycetemcomitans and …

Nutritional Virulence Of Legionella Pneumophila., Ashley M. Best

Electronic Theses and Dissertations

Legionella pneumophila is an environment organism that parasitizes a wide range of protozoa. Growth within the environmental host primes L. pneumophila for infection of human alveolar macrophages when contaminated aerosols are inhaled. Intracellular replication within either host requires the establishment a replicative niche, known as the Legionella-containing vacuole (LCV). Biogenesis of the LCV depends on the type IVb translocation system, the Dot/Icm, to translocation >320 effectors into the host cytosol. Effectors are responsible for preventing lysosome fusion to the LCV, recruitment of ER-derived vesicles to the LCV, and modulation of a plethora of host processes to promote the intracellular …

Functional Similarity Of Prd-Containing Virulence Regulators In Bacillus Anthracis, Malik Raynor

Dissertations and Theses (Open Access)

Bacillus anthracis produces three regulators, AtxA, AcpA, and AcpB, that control virulence gene expression and are members of an emerging class of regulators termed “PCVRs” (Phosphoenolpyruvate-dependent phosphotransferase regulation Domain-Containing Virulence Regulators). AtxA controls expression of the toxin genes; lef, cya, and pag, and is the master virulence regulator and archetype PCVR. AcpA and AcpB are less well studied. AcpA and AcpB independently positively control transcription of the capsule biosynthetic operon capBCADE, and culture conditions that enhance AtxA activity result in capBCADE transcription in strains lacking acpA and acpB. RNA-Seq was used to assess the regulons of the …

Characterization Of The Interaction Between R. Conorii And Human Host Vitronectin In Rickettsial Pathogenesis, Abigail Inez Fish

LSU Doctoral Dissertations

Spotted Fever Group Rickettsia are inoculated into the mammalian host during hematophagous arthropod feeding. Once in the bloodstream and during dissemination, the survival of these pathogens is dependent upon their ability to evade innate host defenses until a proper cellular target is reached. The establishment of a successful infection also relies on the ability of the bacteria to attach and invade target cells, as failure to do so results in destruction of the bacterium. Rickettsia conorii expresses an outer membrane protein, Adr1, which binds the multifunctional human glycoprotein, vitronectin, to promote resistance to complement mediated killing. Homologs of Adr1 are …

In Vitro Assay Development As An Alternative To The Use Of Laboratory Animals For Measuring Clostridium Perfingens Type C Toxoid, Lauren M. Wilmes

School of Veterinary and Biomedical Sciences: Dissertations, Theses, and Student Research

Clostridium perfringens type C produces beta toxin, which is a primary virulence determinate that can cause necrotic enteritis in neonatal animals. Vaccines directed against C. perfringens toxins have shown to be efficacious in preventing disease. However, the production of a commercial vaccine requires not only an efficacious antigen, but also testing methods for quantifying antigens and potency on final product. This research was undertaken to fulfill a need for the reduction in small animal usage to produce and deliver vaccines. The current testing methods are performed in vivo according to the Code of Federal Regulations number 9 (9CFR) United …

Rapid Identification And Typing Of Mycobacterium Avium Complex Using Matrix Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (Maldi-Tof) Library And Biomarker Based Approaches, Claudia Antonika, John Dustin Loy, Raul Barletta, Michael Collins

UCARE: Research Products

Bacteria associated with the Mycobacterium avium complex (MAC) cause significant problems in animal agriculture and cause large economic losses and morbidity of livestock. Two clinically important subspecies of M. avium are M.avium ssp paratuberculosis (MAP) and M. avium ssp hominissuis (MAH). MAP is the etiologic agent of Johne’s disease, a chronic and fatal enteritis in ruminants, that has been linked to Crohn’s disease in humans.1 MAH has zoonotic potential as it is one of the leading causes of secondary infections in AIDS patients. Identification of M. avium in clinical samples is challenging as they have overlapping host ranges and clinical …

Breeding For Resistance In California Strawberry To Verticillium Dahliae, Zachary Christman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This article focuses on breeding resistant strawberries to the fungus Verticillium dahliae, common name Verticillium wilt. This is a serious fungal disease that can result in a loss of 50% or more of a strawberry harvest when grown in infested soil. The main goal is to provide an example of how a cultivar can be made more resistant to a plant pathogen with the use of plant breeding methods.

Since 1930 the University of California, Davis, has been developing strawberry cultivars that are adapted to the agricultural industry and regional farms. Developing cultivars that require fewer inputs are of …

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 …

Adherence Mechanism Analysis: The Role Of Prsa Gene In Lactobacillus Acidophilus And Other Infectious Microorganisms, Nujuma Moussa

AUCTUS: The Journal of Undergraduate Research and Creative Scholarship

No abstract provided.

Antibody Dependent Enhancement Of Visceral Leishmaniasis, Alan K. Mcnolty

All Master's Theses

Leishmaniasis is a parasitic disease caused by protozoans of the genus Leishmania. This vector-born disease, transmitted by biting phlebotomine sandflies, typically manifests in one of three ways. The cutaneous form of the disease is characterized by localized lesions of the skin and is by far the most common manifestation. The visceral form of the disease is caused by parasitic infiltration of internal organs, particularly the spleen, liver, and bone marrow. The mucocutaneous form is caused by parasitic infection of the mucosa in the nose or mouth. While cutaneous leishmaniasis (CL) is often self-healing, visceral leishmaniasis (VL) is fatal if …

Size-Dependent Inhibitory Effects Of Antibiotic Drug Nanocarriers Against Pseudomonas Aeruginosa, Feng Ding, Preeyaporn Songkiatisak, Pavan Kumar Cherukuri, Tao Huang, Xiao-Hong Nancy Xu

Chemistry & Biochemistry Faculty Publications

Multidrug membrane transporters (efflux pumps) are responsible for multidrug resistance (MDR) and the low efficacy of therapeutic drugs. Noble metal nanoparticles (NPs) possess a high surface-area-to-volume ratio and size-dependent plasmonic optical properties, enabling them to serve both as imaging probes to study sized-dependent MDR and as potential drug carriers to circumvent MDR and enhance therapeutic efficacy. To this end, in this study, we synthesized three different sizes of silver nanoparticles (Ag NPs), 2.4 ± 0.7, 13.0 ± 3.1, and 92.6 ± 4.4 nm, functionalized their surface with a monolayer of 11-amino-1-undecanethiol (AUT), and covalently conjugated them with antibiotics (ofloxacin, Oflx) …

Synthesis, Secretion, And Perception Of Abscisic Acid Regulates Stress Responses In Chlorella Sorokiniana, Maya Khasin, Rebecca E. Cahoon, Sophie Alvarez, Richard Beckeris, Seong-Il Eyun, Qidong Jia, Jean-Jack Riethoven, Kenneth Nickerson, Wayne R. Riekhof

Kenneth Nickerson Papers

Abscisic acid (ABA) is a phytohormone that has been extensively characterized in higher plants for its roles in seed and bud dormancy, leaf abscission, and stress responses. Genomic studies have identified orthologs for ABA-related genes throughout the Viridiplantae, including in unicellular algae; however, the role of ABA in algal physiology has not been characterized, and the existence of such a role has been a matter of dispute. In this study, we demonstrate that ABA is involved in regulating algal stress responses. Chlorella sorokiniana strain UTEX 1230 contains genes orthologous to those of higher plants which are essential for ABA …

Relationships Between Factors Influencing Biofilm Formation And Pathogen Retention In Complex Rhizosphere Microbial Communities, Aaron Coristine

Theses and Dissertations (Comprehensive)

Riparian wetlands are unique habitats facilitating all forms of life. The riverbanks of these environments provide ideal conditions for bacteria, plants, and higher organisms. Of particular interest to this research was the variation in microbial community structure at high, intermediate and poor water quality impacted areas. Assessing the capabilities of plants to retain microbial pathogens was identified. Root systems and corresponding soil are ideal locations for bacterial deposition, resulting in attachment at these areas. Biofilm production in these regions is important for long-term establishment, leading to persistence and potential naturalization. Opportunistic pathogens originating from mammalian fecal matter are introduced into …

Acid Sphingomyelinase Is Essential For Vacuolar Development Of A. Phagocytophilum., Chelsea Cockburn

Theses and Dissertations

Obligate intracellular bacteria are significant causes of morbidity and mortality with over two hundred and fifty million infections worldwide annually. One such bacterium, Anaplasma phagocytophilum is the etiologic agent of human granulocytic anaplasmosis (HGA), a tick-transmitted febrile illness. Previous studies have shown that A. phagocytophilum lacks genes for cholesterol biosynthesis and solely relies on Niemann Pick protein type C (NPC)1-mediated low density lipoprotein (LDL)-derived cholesterol to complete its infection cycle.Acid sphingomyelinase (ASMase) is a lysosomal enzyme that is essential for diverse cellular processes including liberation of LDL-derived cholesterol from the lysosome. By first studying A. phagocytophilum, we found that …

Orientia Tsutsugamushi Modulates Endoplasmic Reticulum Stress To Benefit Its Intracellular Growth And Targets Nlrc5 To Inhibit Major Histocompatibility Complex I Expression, Kyle G. Rodino

Theses and Dissertations

Scrub typhus, caused by the obligate intracellular bacterium Orientia tsutsugamushi, afflicts one million people annually. Despite being a global health threat, little is known about O. tsutsugamushi pathogenesis. Here, we demonstrate that O. tsutsugamushi modulates the ER and ER-associated processes as mechanisms of nutritional virulence and immune evasion. To obtain amino acids to fuel replication, O. tsutsugamushi simultaneously induces ER stress and the unfolded protein response (UPR) while inhibiting ER-associated degradation (ERAD) during early infection time points. During exponential growth, the bacterium releases the ER bottleneck, resulting in generation of ERAD-derived amino acids that it parasitized for replication. …

Comparison Between Listeria Sensu Stricto And Listeria Sensu Lato Strains Identifies Novel Determinants Involved In Infection, Jakob Schardt, Grant Jones, Stefanie Müller-Herbst, Kristina Schauer, Sarah E. F. D'Orazio, Thilo M. Fuchs

Microbiology, Immunology, and Molecular Genetics Faculty Publications

The human pathogen L. monocytogenes and the animal pathogen L. ivanovii, together with four other species isolated from symptom-free animals, form the "Listeria sensu stricto" clade. The members of the second clade, "Listeria sensu lato", are believed to be solely environmental bacteria without the ability to colonize mammalian hosts. To identify novel determinants that contribute to infection by L. monocytogenes, the causative agent of the foodborne disease listeriosis, we performed a genome comparison of the two clades and found 151 candidate genes that are conserved in the Listeria sensu stricto species. Two factors were …

Changing Antimalarial Drug Sensitivities In Uganda, Stephanie Alexis Rasmussen

Dissertations, Masters Theses, Capstones, and Culminating Projects

Dihydroartemisinin-piperaquine (DP) has demonstrated excellent efficacy for the treatment and prevention of malaria in Uganda. However, resistance to both components of this regimen has emerged in Southeast Asia. The efficacy of artemether-lumefantrine, the first-line regimen to treat malaria in Uganda, has also been excellent, but continued pressure may select for parasites with decreased sensitivity to lumefantrine. To gain insight into current drug sensitivity patterns, ex vivo sensitivities were assessed and genotypes previously associated with altered drug sensitivity were characterized for 58 isolates collected in Tororo, Uganda from subjects presenting in 2016 with malaria from the community or as part of …

Vibrio Vulnificus Monitoring Along The Coastal Bend And The Rio Grande Valley, Texas, Louay Bachnak

Honors Theses

Vibrio vulnificus is a common opportunistic pathogen found in marine, coastal, and estuarine waters. This one micrometer microorganism is the leading cause of deaths in the United States due to food poisoning after consumption of raw or undercooked seafood. The optimal temperature for survival is between 15.6°C and 35.0°C with moderate salinities – conditions frequently found in the Gulf of Mexico (Lin, Payne, & Schwarz, 2003).

In the United States, V. vulnificus infections are more common in states bordering the Gulf of Mexico, including Texas. However, infections can still occur in individuals consuming infected food more inland or sustain wounds …

Fluorescence-Reported Allelic Exchange Mutagenesis Reveals A Role For Chlamydia Trachomatis Tmea In Invasion That Is Independent Of Host Ahnak, M. J. Mckuen, Konrad E. Mueller, Y. S. Bae, Kenneth A. Fields

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Development of approaches to genetically manipulate Chlamydia is fostering important advances in understanding pathogenesis. Fluorescence-reported allelic exchange mutagenesis (FRAEM) now enables the complete deletion of specific genes in C. trachomatis L2. We have leveraged this technology to delete the coding sequences for a known type III effector. The evidence provided here indicates that CT694/CTL0063 is a virulence protein involved in chlamydial invasion. Based on our findings, we designate the gene product corresponding to ct694-ctl0063 translocated membrane-associated effector A (TmeA). Deletion of tmeA did not impact development of intracellular chlamydiae. However, the absence of TmeA manifested as a decrease in infectivity …

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

Dissertations and Theses (Open Access)

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

Role Of Incompatibility Group 1 (Inci1) Plasmid-Encoded Factors On Salmonella Enterica Antimicrobial Resistance And Virulence, Pravin Raghunath Kaldhone

Graduate Theses and Dissertations

Foodborne illnesses are a leading cause of infectious diseases in the world. Among enteric organisms Salmonella is a key pathogen. It’s high prevalence in poultry and other food-animal sources make it imperative to study. Salmonella has the ability to modify its genetic content with help of mobile genetic elements such as plasmids. Incompatibiltiy group 1 (IncI1) plasmids are commonly reported in Salmonella. This study evaluates role on IncI1 plasmids in antimicrobial resistance and virulence in Salmonella. Genetic determinants of resistance and virulence are noted among our IncI1-containing Salmonella isolates. These genetic elements are also transferable and reported to carry respective …

Experimental Approaches To Understand And Control Salmonella Infection In Poultry, Yichao Yang

Graduate Theses and Dissertations

Salmonella is a major foodborne pathogen around the world and chickens are the major reservoir to transmit Salmonella into the human food chain. For decreasing the infection of Salmonella, we developed six attenuated live vaccines based on Salmonella Enteritidis (SE) and Typhimurium (ST) for testing the cross-serovar and cross-serogroup protection from the challenge of Salmonella Heidelberg and Campylobacter jejuni. One of the constructed vaccine strain showed ability to protect against challenge from Salmonella Heidelberg. Even though some preventive approaches are able to decrease Salmonella colonization in the gastrointestinal tract of chickens or other farm animals, Salmonella transmission mechanisms remain unclear. …

The Molecular Mechanism Of N-Acetylglucosamine Side-Chain Attachment To The Lancefield Group A Carbohydrate In Streptococcus Pyogenes, Jeffrey Rush, Rebecca J. Edgar, Pan Deng, Jing Chen, Haining Zhu, Nina M. Van Sorge, Andrew J. Morris, Konstantin V. Korotkov, Natalia Korotkova

Molecular and Cellular Biochemistry Faculty Publications

In many Lactobacillales species (i.e. lactic acid bacteria), peptidoglycan is decorated by polyrhamnose polysaccharides that are critical for cell envelope integrity and cell shape and also represent key antigenic determinants. Despite the biological importance of these polysaccharides, their biosynthetic pathways have received limited attention. The important human pathogen, Streptococcus pyogenes, synthesizes a key antigenic surface polymer, the Lancefield group A carbohydrate (GAC). GAC is covalently attached to peptidoglycan and consists of a polyrhamnose polymer, with N-acetylglucosamine (GlcNAc) side chains, which is an essential virulence determinant. The molecular details of the mechanism of polyrhamnose modification with GlcNAc are …

Human Rickettsial Pathogen Modulates Arthropod Organic Anion Transporting Polypeptide And Tryptophan Pathway For Its Survival In Ticks, Vikas Taank, Shovan Dutta, Amrita Dasgupta, Durland Fish, John F. Anderson, Hameeda Sultana, Girish Neelakanta

Biological Sciences Faculty Publications

The black-legged tick Ixodes scapularis transmits the human anaplasmosis agent, Anaplasma phagocytophilum. In this study, we show that A. phagocytophilum specifically up-regulates I. scapularis organic anion transporting polypeptide, isoatp4056 and kynurenine amino transferase (kat), a gene involved in the production of tryptophan metabolite xanthurenic acid (XA), for its survival in ticks. RNAi analysis revealed that knockdown of isoatp4056 expression had no effect on A. phagocytophilum acquisition from the murine host but affected the bacterial survival in tick cells. Knockdown of the expression of kat mRNA alone or in combination with isoatp4056 mRNA significantly affected A. phagocytophilum survival …