Bacteriology Commons^™

Antibiotic Resistance Profile Of Enterobacteriaceae Isolated From Healthy Pigs In The Republic Of Armenia, Yura Shirvanyan, Irma Artushyan, Lilit Hovsepyan, Ashkhen Shirvanyan, Elmira Ghazaryan, Tigran Markosyan

The Thai Journal of Veterinary Medicine

The rising prevalence of antimicrobial resistance (AMR) among Enterobacteriaceae in livestock presents a significant threat to both animal and human health. This study investigates the antibiotic resistance profiles of Enterobacteriaceae isolated from 160 samples collected from the lymph nodes of healthy pigs in Armenia. Fifty isolates were identified, including Escherichia coli (24), Klebsiella spp. (10), Salmonella spp. (6), Raoultella ornithinolytica (4), Pseudomonas aeruginosa (4), and Proteus mirabilis (2). Resistance was evaluated using the disk diffusion method against 22 antibiotics from nine classes. Alarmingly, 94.5% of isolates were resistant to clarithromycin and 90.3% to erythromycin, while resistance to cephalothin and amoxicillin …

Antibacterial Activity Of Endophytic Actinobacteria Isolated From Ziziphus Mauritiana Against Multidrug-Resistant Strains, Hafifatunil Khairani, Jepri Agung Priyanto, Muhammad Eka Prastya, Dwi Retnowati

Makara Journal of Science

Increasing resistance to existing antibiotics has led to a need for new alternative sources. Among the possibilities that need to be explored is the endophytic actinobacteria associated with Ziziphus mauritiana. The present study aimed to evaluate the antibacterial activity of endophytic actinobacteria isolated from Z. mauritiana against five multidrug-resistant bacterial strains. Thirty actinobacteria isolates were obtained from the roots, stem, and leaves of the plant using the serial dilution technique. Using a double-layer agar test, we found that colonies from five of the 30 isolates (16%) exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and the M18 strain of Bacillus …

Transcription Factor Binding And Discovery Of Novel Gene In The Opportunistic Human Pathogen, Pseudomonas Aeruginosa, Alaina Westee

Symposium of Student Scholars

Pseudomonas aeruginosa (PA) is a gram-negative, ubiquitously-found bacterium that primarily causes nosocomial, or hospital-borne, infections within immunocompromised patients. Therefore, it has been deemed a critical priority pathogen by the World Health Organization (WHO) and the Center for Disease Control (CDC), generating a need for research on its fundamental biology. The Van Dyke laboratory focuses on proteins called transcription factors, which promote or repress gene expression to regulate an organism’s functioning. We are specifically studying the cadmium-responsive transcription factor, CadR, due to the importance of metals in virulence and the lack of information on PA’s response to metal fluctuations. We intend …

Thermophilic Microbiota Of Fifth Water Hot Springs: A Genomic Perspective, Ethan Powers, Zack Galbraith, Trever Thurgood

Annual Research Symposium

Geothermal hot springs provide unique microbial habitats characterized by extreme temperatures, variable pH, and diverse geochemical conditions. This study investigates the microbial diversity of three hot spring locations in Diamond Fork Canyon, Utah—Diamond Fork Warm Springs, Fifth Water Hot Springs, and Monk’s Hollow Trailhead—using Oxford Nanopore MinION sequencing of the 16S rRNA gene. Samples were collected in triplicate and analyzed to identify the bacterial composition, with a focus on potential opportunistic pathogens. Our results revealed a diverse microbial community, including members of Pseudomonas, Comamonas, Helicobacter, and Flavobacterium, some of which are known for biofilm formation, antibiotic …

The Use Of Ethyl Lauroyl Arginate Encapsulated In Organic Nanoparticles Within Boar Semen Extenders To Control Bacterial Growth And Preserve Sperm Quality During Short-Term Storage Without Antibiotics, Congbang Ngo, Naiyaphat Nittayasut, Teerapong Yata, Junpen Suwimonteerabutr, Nuvee Prapasarakul, Jane M. Morrell, Padet Tummaruk

The Thai Journal of Veterinary Medicine

The aim of the present study was to investigate the effect of adding ethyl lauroyl arginate (ELA), encapsulated in organic nanoparticles, to a semen extender without antibiotics on sperm quality and bacterial load during short-term storage. Three ejaculates from Duroc boars were divided into four equal portions and diluted with Beltsville Thawing Solution to produce semen doses containing 3 billion spermatozoa in 80 ml. The extended semen did not include antibiotics but instead incorporated different concentrations of ELA nanoparticles into the extenders: 0 ppm, 5 ppm, 10 ppm, and 15 ppm. The semen doses were stored for 4 days, with …

Functional Analysis Of Ligand Binding Domain 2 Of Outer Surface Protein C Of Borreliella Burgdorferi, Gavin Z. Chambers

Theses and Dissertations

Lyme disease, caused by the spirochete Borreliella burgdorferi, is the most common vector-borne infection in North America. A critical determinant of early mammalian infection is outer surface protein C (OspC), a highly variable lipoprotein that is indispensable for spirochete survival but whose precise function remains unresolved. OspC has been proposed to mediate diverse roles, including complement evasion, adhesion, tissue dissemination, and antiphagocytic activity, supporting the view that it is a multifunctional virulence factor. Structural studies have identified two putative ligand-binding domains (LBD1 and LBD2), with LBD2 forming a solvent-exposed crown at the membrane-distal end of the OspC dimer.

To …

The Impact Staphylococcus Aureus Has On Conventional And Organic Dairy Herds In New Hampshire And New York, Jacqueline Rose Holmes

Honors Theses and Capstones

Staphylococcus aureus is a potentially virulent bacterium that causes mastitis in dairy cattle. The toxins produced from S. aureus impact host immunity, damage the mammary gland, and can adapt to cause antimicrobial resistance. It is important to manage both organic and conventional farms correctly by practicing proper hygiene while milking and providing a clean environment. There is a significant increase of S. aureus cases on organic farms compared to conventional, so there may be ways in which organic management and treatment options could be altered to reduce economic loss and animal suffering. The thesis focuses on the involvement S. aureus …

The Role Of Horizontal Gene Transfer In Antibiotic Resistance Amidst Prevalent Community And Healthcare-Associated Mrsa Rates, Gabrielle Nascimento

Honors College Theses

In recent decades, cases of community-acquired MRSA (CA-MRSA) and healthcare-associated MRSA (HA-MRSA) have been on the rise. The ability of antibiotic resistance to transfer between microorganisms greatly expands its threat to the effective treatment and containment of bacterial infections. The mecA gene is found on a mobile cassette within the Staphylococcal cell and encodes for PBP2a, an alternate version of penicillin-binding protein (PBP) with less binding affinity for β-lactam antibiotics, increasing resistance to the effects of antibiotics. The goal of this research is to investigate the horizontal transfer of the mecA gene between various Staphylococcus species as well as to …

A Novel Silver-Ruthenium-Based Antimicrobial Kills Gram-Negative Bacteria Through Oxidative Stress-Induced Macromolecular Damage, Patrick O. Tawiah

Theses and Dissertations

The rise in drug-resistant bacteria, together with the decline in antibiotic development, requires new strategies for infectious disease control. Gram-negative pathogens are particularly challenging to combat due to their outer membrane. This study highlights the effectiveness of the silver-containing antimicrobial AGXX® against the Gram-negative bacterium Escherichia coli. AGXX® is a promising silver coating that presumably kills bacteria through the generation of reactive oxygen species (ROS). However, neither AGXX®’s mode of action is fully understood, nor have its effects on Gram-negative bacteria or bacterial response and defense mechanisms towards AGXX® been studied in detail. Here, I report that the bactericidal …

Investigating Regulation And The Regulome Of The Nucleic Acid Binding Protein Spovg Within Borrelia Burgdorferi, Timothy C. Saylor

Theses and Dissertations--Medical Sciences

Prior studies indicated Borrelia burgdorferi SpoVG protein was regulated, SpoVG binds specifically to a number of nucleic acids, and SpoVG binds to the non-variable section of the major virulence factor vlsE. Although a direct transcriptional activator or inhibitor was not elucidated, it is shown that SpoVG is regulated based on cell culture density independent of the growth rate of B. burgdorferi, indicating that SpoVG regulation is outside the scope of the alternative sigma factor RpoS. Using a dCas9 CRISPRi construct to target SpoVG resulted in protein expression trending towards upregulation of the BosR-RpoS regulon, and a marked decrease …

Isolation And Characterization Of Rhizobia Bacteria From Midwest Soils, Jr Loya

Electronic Theses and Dissertations

Symbiotic bacteria, known as rhizobia, can colonize the roots of legume plants and then convert atmospheric nitrogen into a usable form by the host through the process called biological nitrogen fixation (BNF). Many of these bacteria produce other plant-growth-promoting benefits, such as nutrient acquisition, phytohormone production, and the modification of plant stress responses. Agricultural inoculants made from these bacteria have helped reduce the need for man-made nitrogenous fertilizers, known causes of pollution and eutrophication. There are additional benefits in developing bacteria inoculants local to regional soils. The ability to survive and compete in Midwest soil and climates present an opportunity …

Bacterial Two-Hybrid Systems Evolved: Innovations For Protein-Protein Interaction Research, Rebecca M. Richardson, Steven M. Pascal

Chemistry & Biochemistry Faculty Publications

Bacterial two-hybrid (B2H) systems offer a versatile platform for detecting protein-protein interactions (PPIs) in vivo. Originally developed to study bacterial transcriptional regulators, these systems have evolved to support a wide range of applications, including interaction mapping, domain analysis, and high-throughput screening. This review surveys the development and expansion of B2H systems across diverse biological contexts. We highlight technical considerations, platform-specific innovations, and recent adaptations that extend the utility of B2H systems in both prokaryotic and eukaryotic protein interaction research environments. By comparing different B2H variants and discussing their integration with complementary approaches, we provide a framework for leveraging these …

Antibody-Induced Multicellular Behaviors Of Salmonella Typhimurium, Samantha K. Lindberg

Electronic Theses & Dissertations (2024 - present)

Salmonella enterica is a globally distributed bacterial pathogen that is commonly acquired through consumption of contaminated food and water. The enterica subspecies includes over 1500 unique subvariants, or serovars, that are classified by antigen presentation. Due to its global environmental prevalence, broad host range, and increasing pathogenicity, serovar Typhimurium is of particular concern for human and animal health, as well as food safety. Once in the gastrointestinal tract, Salmonella Typhimurium (STm) exploits host immune mechanisms, implements an arsenal of virulence factors, and outcompetes the microbiota to invade the intestinal epithelium. While STm infections are generally self-limiting and relatively mild, emerging …

Biochemical And Molecular Analysis Of Anr-Dependent Microoxic Fitness Factors In Pseudomonas Aeruginosa, Stacie E. Balsam

Dartmouth College Ph.D Dissertations

Pseudomonas aeruginosa is a prominent opportunistic pathogen that is often found in microoxic environments like sites of infection and colony biofilms. P. aeruginosa can grow at oxygen (O2) at concentrations as little as 3 μM and also grows anaerobically by generating energy using nitrate as an alternate electron acceptor. An important way P. aeruginosa adapts to low O2 is through Anr, a transcription factor that upregulates many genes important for microoxic and anoxic fitness.

Specifically, Anr regulates mhr which encodes a hemerythrin protein (Mhr) that binds O2 with affinities relevant to microoxia and is also necessary for full fitness of …

Interactions Between Lipopolysaccharide And Capsule Retention In Klebsiella Pneumoniae And The Resultant Effects On Macrophages, Juliane Leigh Nguy

UNF Graduate Theses and Dissertations

Klebsiella pneumoniae is the third most common cause of nosocomial infections in the United States. The capsular polysaccharides (CPS) are virulence factors allowing K. pneumoniae to evade host immune systems. The current model of capsule structure indicates that CPS fibrils interact with the external O-antigen of lipopolysaccharide molecules to enhance retention to the bacterial outer membrane. These interactions may influence pathogenicity in clinically relevant strains. This study characterized alterations to LPS and CPS structure, the impact of these changes on capsule retention, membrane permeability, biofilm formation, and macrophage interactions. LPS and CPS were quantified and visualized in four strains of …

Optimization Of L-Citrulline Production In Corynebacterium Glutamicum, And The Effect Of The Human Small Intestine Environment, Simran S. Ghulldu

Honors Undergraduate Theses

L-citrulline is a crucial amino acid involved in nitric oxide production, which supports cardiovascular health, physical performance, and intestinal well-being. Nitric oxide deficiency is linked to conditions like hypertension, highlighting the need for efficient L-citrulline production. This study attempts to enhance L-citrulline synthesis in Corynebacterium glutamicum, a bacterium widely used in industrial amino acid production, as well as test a The hypothesis is that overexpressing carAB, which encodes carbamoyl phosphate synthetase, will increase carbamoyl phosphate levels and boost L-citrulline production. Two C. glutamicum strains were used: a wild type and the CRBG strain, which has mutations that promote …

Development Of A Proposed Selective Medium For The Isolation And Differentiation Of P. Sordellii, Dimyana Bottros

Honors Undergraduate Theses

Clostridium, a genus of anaerobic, spore-forming bacteria, includes clinically and ecologically significant species like Clostridium difficile and Paeniclostridium sordellii. C. difficile causes antibiotic-associated colitis, while P. sordellii is linked to fatal infections and spontaneous abortions. Recent studies found both species in marine sediments, suggesting their role in environmental and wildlife health disturbances, including the 2013 mass mortality of over 300 manatees in the Indian River Lagoon. However, isolating and differentiating P. sordellii is challenging due to the lack of selective media optimized for its growth. This thesis proposes a novel selective medium tailored to P. sordellii’s physiological …

Characterization Of Adaptive Quorum Sensing In Pseudomonas Aeruginosa, Kayla Simanek

Electronic Theses & Dissertations (2024 - present)

Pseudomonas aeruginosa is an opportunistic pathogen that is highly antibiotic resistant and causes tens of thousands of infections each year. It persists in hospitals by forming biofilms on medical equipment like ventilators and catheters, making it difficult to eradicate. Biofilm formation, among other virulence factors of P. aeruginosa, is regulated through quorum sensing, a mechanism of bacterial communication. Quorum sensing is primarily coordinated through LuxI-R type systems comprised of an autoinducer synthase and receptor, respectively. Canonically, the first system to be expressed is LasI-R, and LasR upregulates the second arm of the quorum sensing network, the RhlI-R system. Research …

Reversible Degradation Of Peptidoglycan By Lytic Transglycosylases, Aaron Devereaux

Theses and Dissertations (Comprehensive)

Antimicrobial resistance continues to be a burden on the global healthcare system with an estimated cost of billions of dollars and millions of deaths each year. Recently, there has been little to no development on new antibiotics to treat bacterial infection, and any that are developed become resisted to within a few years. Both Gram-positive and Gram-negative bacteria contain a mesh-like layer called peptidoglycan (PG) that surrounds their cells providing strength, cell shape, and protection from their environments. This layer is a polymer of N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) connected via a b-1,4-glycosidic bond, with each strand being cross-linked …

Evaluating The Effectiveness Of Benguet Pine (Pinus Kesiya) Xylem For Deep Well Water Filtration, Allen Conner C. Hizon, Robert Zachary M. Santos, Juan Jose B. Lacson, Jefferson Danilo G. Villarin, Juan Carlo T. Gumangan

Sinaya: A Philippine Journal for Senior High School Teachers and Students

Even today, many rural and remote communities still do not have access to safe drinking water, which is a basic right of every human. To address this problem, the effectiveness of the Benguet pine tree (Pinus kesiya) xylem as a sustainable water filtration method for well water was investigated. The physical and chemical properties of the filtered and unfiltered deep well water were tested: the total dissolved solids (TDS) and the electrical conductivity using a 5-in-1 electronic water quality tester and the pH level using pH strips. On the other hand, the microbiological metrics, such as heterotrophic plate …