Bacteriology Commons^™

Investigating The Synthesis And Antibacterial Activity Of A Main-Chain Cationic Polymer, Emily Smith

Honors Theses

Antibiotic resistance is a growing threat to public health. Due to the overuse of antibiotics in agriculture, the overprescription of antibiotics, and the misuse of antibiotics by patients, antibiotic resistance is spreading at an alarming rate. As antibiotic resistance spreads, the antibiotics we depend on to treat common infections become ineffective. Therefore, it is imperative to develop novel treatments for infections that do not increase the prevalence of antibiotic resistance. One treatment being explored is the use of synthetic polymers with antibacterial properties. Synthetic polymers are advantageous because they can be synthesized from widely available precursors and their structure is …

Elasmobranchii Oral Microbiome Diversity Within Southeast Florida: Implications Of Shark Zoonotic And Antibiotic Resistant Pathogens Associated With Human Interactions, Amanda Finnefrock

All HCAS Student Capstones, Theses, and Dissertations

Sharks are incredibly common in the Atlantic and Gulf waters surrounding Florida. Despite the prevalent nature of these animals, little research exists on the composition of their microbial communities (or “microbiomes”). Here we aim to determine the microbial makeup of the oral environment of sharks so that we can determine if there are any bacteria of clinical significance to humans, such as being antibiotic-resistant or having elevated capability for pathogenicity. A total of 41 samples were collected from the mouths and teeth of bull, Caribbean reef, great hammerhead, lemon, nurse, and sandbar sharks caught in Southeast Florida using sterile swabs …

Evolution Of Antibiotic Responses During Chronic P. Aeruginosa Infections In The Human Lung, David Frank Ritz

Dartmouth College Ph.D Dissertations

Typical antibiotic susceptibility testing (AST) of microbial samples is performed in homogeneous cultures in batch environments, which does not account for the highly heterogeneous and dynamic nature of antibiotic responses. The most common mutation found in P. aeruginosa lineages evolved during chronic cystic fibrosis infections in the human lung, a loss of function of repressor MexZ, increases basal levels of multidrug efflux MexXY, but does not increase resistance by traditional minimal inhibitory concentration (MIC) assays. Here, we use single cell microfluidics to show that P. aeruginosa’s response to aminoglycosides is highly heterogeneous, with only a subpopulation of cells surviving exposure. …

Elucidating The Relationship Between Water Quality And Antibiotic Resistance Of Rainwater Microbes Across Western Humboldt County, Theo P. Murphy, Eve Wendley, Justice Laskowski, Tyler Paredes

Humboldt Journal of Microbiology

Limited studies have been conducted regarding the fecal contamination and microbial dispersal through rainwater, with no known studies investigating the potential connection between antibiotic resistant microbes and water quality in rainwater. This study seeks to identify the presence of a correlation between water quality and incidence of antibiotic resistance in rainwater microbes. We hypothesize that there will be a correlation between these two variables. We additionally anticipate a high incidence of fecal contamination across rural and urban collection sites alike, with fecal contamination being more prevalent in rural areas than urban locals. To determine water quality, we measured the concentration …

Synergistic Cefiderocol-Containing Antibiotic Combinations Active Against Highly Drug-Resistant Acinetobacter Baumannii Patient Isolates With Diverse Resistance Mechanisms, Justin Halim, Andrew P. Keane, Jeannete Bouzo, Tope Aderibigbe, Jessica A. Chicola, Katie T. Nolan, Keertana Jonnalagadda, Jason X. Tran, Valerie J. Carabetta

Rowan-Virtua School of Osteopathic Medicine Departmental Research

BACKGROUND: Acinetobacter baumannii is a nosocomial pathogen known for rapidly developing resistance to nearly all antibiotics, including last-line agents. Cefiderocol, a novel siderophore cephalosporin, has shown in vitro activity against A. baumannii and is now used clinically, but resistance is emerging. Data on cefiderocol-based antibiotic combinations are limited.

OBJECTIVES: To evaluate the in vitro activity of cefiderocol alone and in combination with other antibiotics against XDR and PDR A. baumannii clinical isolates, and to explore resistance mechanisms underlying cefiderocol synergy.

METHODS: We tested 21 XDR/PDR clinical isolates and one NDM-1-producing strain using broth microdilution and checkerboard assays with cefiderocol and …

Resistant & Persistent Bacterial Cells, Jean-Louis Bru

Open Educational Resources

An activity on the difference between resistant & persistent bacterial cells. This activity aims to build on the pre-lecture materials about resistant bacterial cells, so that students can make a connection toward persistent cells. In both cases, they make antibiotics less effective.

Learning Objectives

Recognize the importance of antibiotics in fighting bacterial infections. Understand how bacterial species become antibiotic resistant. Determine the difference between resistant and persistent bacterial cells.

Social and Collaborative

Students work together on this in-class activity in groups of 2-4 (3, ideally). Each student will have one of the following roles: encourager, recorded, investigator, and time keeper. …

Clinical Characteristics And Outcomes Of Pediatric Staphylococcal Scalded Skin Syndrome (Ssss) At An Inner-City Tertiary Care Center, Nina Kb Gust Md, Ashley Frei Bs, Rebecca M. Adams Bs, Elika Ridelman Phd, Christina Shanti Md, Ronald Thomas Phd, Jocelyn Y. Ang Md

Medical Student Research Symposium

Introduction

Staphylococcal Scalded Skin Syndrome (SSSS) is a blistering skin condition caused by a toxin-producing staphylococcus species. Epidemiologic studies on pediatric SSSS in the United States are limited, with a reported incidence of 7.67 cases per million children and 45.1 per million infants. Immature renal function, lack of protective antibodies, and increased exotoxin target desmoglein-1 are hypothesized to increase incidence in younger children. We aimed to determine clinical and microbiological characteristics of pediatric SSSS and factors that could help predict disease severity.

Methods

A retrospective chart review was performed for admitted patients under 18 years old diagnosed with SSSS from …

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 …

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 …

Characterizing The Role Of Pa5189 Of Pseudomonas Aeruginosa In Deletion And Overexpression Mutants, Seh Na Mellick

Theses/Capstones/Creative Projects

In the context of rising multidrug resistance in biofilm-forming pathogens like Pseudomonas aeruginosa, this study investigates the role of the understudied transcription factor PA5189 in antibiotic resistance and biofilm formation. PA5189 deletion and overexpression mutants were created in a parent P. aeruginosa strain using pEX18Tc-based recombinant suicide vectors, with genotypic verification of putative triparental conjugants achieved through restriction digestion and PCR. The study revealed that PA5189 overexpression significantly increases resistance to commonly used broad spectrum antibiotics such as ciprofloxacin and imipenem. Additionally, differential expression of PA5189 was found to notably affect biofilm formation, with variations contingent on the nutrient …

Harmonizing Soybean-Associated Beneficial Bacteria For Sustainable Cultivation, Jonas J. Padilla

LSU Master's Theses

Long-term reliance on agrochemicals, such as fertilizers and pesticides, to improve crop productivity can severely impact soil physicochemical properties and health. This eventually leads us to completely depend on these chemicals to sustain the needs of our crops. To resuscitate the deteriorating state of our arable lands, we need to shift from traditional farming to more sustainable crop management. One of the alternatives that we can use instead of these chemicals is the utilization of microorganisms that can perform a variety of beneficial functions for the growth and development of crops. Recently, seed-treating materials made up of bacterial consortia were …

An Exploration Of The Effectiveness Of Xanthorrhiza Simplicissima And Its Secondary Alkaloids As Antibiotics Against Staphylococcus Aureus With The Use Of Reserpine, Donald Bothe, Savita Chaurasia

Undergraduate Theses

Xanthorhiza simplicissima is a plant that is steeped in medical history. It has been used for hundreds of years by the Native Americans, and later by the Europeans, of Appalachia for its medicinal properties. One of the most useful medical applications of this plant are its antibiotic properties, as typified by its use as a tea that was consumed to treat mouth sores. These antibiotic properties can be attributed to some of its secondary alkaloids such as berberine, liriodenine, oxyacanthine, and magnoflorine. These compounds have been studied in other systems; however, oxyacanthine and magnoflorine have not been researched in tandem …

Turbidimetric Bioassays: A Solution To Antimicrobial Activity Detection In Asymptomatic Bacteriuria Isolates Against Uropathogenic Escherichia Coli, Ciara Kenneally, Craig P. Murphy, Roy D. Sleator, Eamonn P. Culligan

Department of Biological Sciences Publications

Traditional bacteriocin screening methods often face limitations due to diffusion-related challenges in agar matrices, which can prevent the peptides from reaching their target organism. Turbidimetric techniques offer a solution to these issues, eliminating diffusion-related problems and providing an initial quantification of bacteriocin efficacy in producer organisms. This study involved screening the cell-free supernatant (CFS) from eight uncharacterized asymptomatic bacteriuria (ABU) isolates and Escherichia coli 83972 for antimicrobial activity against clinical uropathogenic E. coli (UPEC) strains using turbidimetric growth methods. ABU isolates exhibiting activity against five or more UPEC strains were further characterized (PUTS 37, PUTS 58, PUTS 59, S-07-4, and …

Methionyl-Trna Synthetase Synthetic And Proofreading Activities Are Determinants Of Antibiotic Persistence, Whitney N. Wood, Miguel Angel Rubio, Lorenzo Eugenio Leiva, Gregory J. Phillips, Michael Ibba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Bacterial antibiotic persistence is a phenomenon where bacteria are exposed to an antibiotic and the majority of the population dies while a small subset enters a low metabolic, persistent, state and are able to survive. Once the antibiotic is removed the persistent population can resuscitate and continue growing. Several different molecular mechanisms and pathways have been implicated in this phenomenon. A common mechanism that may underly bacterial antibiotic persistence is perturbations in protein synthesis. To investigate this mechanism, we characterized four distinct metG mutants for their ability to increase antibiotic persistence. Two metG mutants encode changes near the catalytic site …

Diagnosis Of Urinary Tract Infections And Rapid Molecular Characterization Of Antibiotic Resistance, Mohammed Harris

All Dissertations

Urinary tract infections (UTIs) are one of the most common infectious clinical entities in both community and hospital settings. They have a broad range of clinical severity yet inflict large epidemiological burden of morbidity and mortality on patients and the healthcare system with billions of dollars in cost of treatment. Understanding what methods are optimal for diagnosing UTIs are critical to mitigate the marked impact and cost of these infections.

Chapter 1 and 2 in this work surveys the broad array of diagnostic modalities for UTIs and highlights their advantages and limitations in the context of the current standard of …

Effects Of Altering Physiologically Relevant Cholesterol Levels And Media Types On Porin Gene Expression In Klebsiella Pneumoniae And The Resulting Impact On Antibiotic Resistance, Megan R. Camden

UNF Graduate Theses and Dissertations

Klebsiella pneumoniae is a Gram-negative, non-motile bacterium belonging to the Enterobacteriaceae family. K. pneumoniae is a rising threat in the clinical setting, as there has been a large increase in the presence of antibiotic resistant isolates. While much research is conducted on laboratory and clinical strains of bacteria, not much is known regarding the impact that human physiology can have on bacterial gene expression, and in response, to antibiotic susceptibility. The goal of this study is to determine if physiologically relevant cholesterol levels and media types impact porin gene expression and antibiotic resistance in K. pneumoniae. To accomplish this, …

Functional Residues Of Cjpata, Robert Lamont

Theses and Dissertations (Comprehensive)

Antibiotic resistance in pathogenic bacteria continues to challenge clinicians and threaten the lives of infected individuals. For this reason, new classes of antibiotics or new targets for antibiotic therapy are needed to circumvent this global health crisis. In Gram-negative bacteria, the enzymes peptidoglycan O-acetyltransferase A and B (PatA and PatB), are responsible for adding acetyl groups to the C-6 hydroxyl group of N-acetyl muramic acid (MurNAc) in peptidoglycan (PG). These acetyl groups are responsible for inhibiting the activity of lysozyme from host organisms that hydrolyze the β1-4 glycosidic linkage between MurNAc and N-acetylglucosamine (GlcNAc). The acetyl groups …

Elucidation Of Gene Essentiality And Genetic Determinants Of Intrinsic P-Aminosalicylic Acid Resistance In Mycobacterium Kansasii, Keith J. Levendosky

Dissertations, Theses, and Capstone Projects

Mycobacterium kansasii (Mk) is an opportunistic pathogen capable of causing tuberculosis-like pulmonary disease in immunocompromised individuals and those with other risk factors including chronic obstructive pulmonary disease or malignancy. Mk is frequently isolated from man-made water sources where it forms resilient biofilms, posing a health risk to these susceptible individuals. Despite its medical relevance as an environmental pathogen, and a close phylogenetic relationship with the obligate pathogen Mycobacterium tuberculosis (Mtb), few studies to date have probed the molecular biology and genetics of Mk. Here, we sought to apply a transposon (Tn) mutagenesis tool to dissect …

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, …

Resolving The Repression Pathway Of Virulence Gene Hila In Salmonella, Alexandra King, Lon Chubiz Phd, Brenda Pratte, Lauren Daugherty

Undergraduate Research Symposium

Salmonella is a relatively abundant, virulent species of bacteria that is most known for spreading gastrointestinal diseases through food. These illnesses result in approximately 1.35 million infections, including over 25,000 hospitalizations each year, in the U.S. alone (CDC.gov). As antibiotic resistance becomes an increasingly urgent public health problem, the importance of developing alternative treatment methods is only becoming more crucial. One of the genes responsible for this virulence is known as hilA. HilA is the main transcriptional regulator of Salmonella Pathogenicity Island-1 gene (UniProt). SPI-1 plays an important role in the invasion of Salmonella into epithelial cells. The proteins encoded …

Diversity Of Bacteriophage In Burkholderia Species, Abigail Price

Honors Projects

Bacteriophages are viruses that infect and replicate within bacteria and offer the potential of a therapeutic alternative to chronic infections that do not respond to antibiotic-based therapies. B. vietnamiensis is one of a number of Burkholderia species involved with chronic drug resistant infections in the lungs of individuals with compromised respiratory systems, as found in those with chronic obstructive pulmonary disease and, most especially, are of particular significance in patients with cystic fibrosis. The diversity of the Burkholderia species is explored by using online databases and looking at bacteriophage or phage-encoding viruses found in B. vietnamiensis. The open reading frames …

Investigating Antimicrobial Properties Of Snake Venoms Against B. Cereus, B. Subtilis, E. Coli, And P. Vulgaris, Savannah Elaine Berger

Honors Program Theses and Research Projects

The increasing incidence of antibiotic resistant bacterial infections has provoked the attention of health officials and scientists as a major threat to global public health. Antibiotic resistance is the product of overprescription by doctors, ineffective or shortened dosing by the patient, and more. When a bacterial infection is ineffectively treated as such, persistent pathogenic cells are given the opportunity to proliferate and spread their resistance to other cells. With bacteria utilizing such tools to fight and ultimately resist our current treatment methods, investigation towards the next novel mechanism of inhibition is essential. Venom is of particular interest to many scientists …

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 …

The Role Of The Msaabcr Operon In Cell Wall Integrity And Programmed Cell Death During Biofilm Development, Bibek G C

Dissertations

Staphylococcus aureus is an important human pathogen in both community and health care settings. Biggest challenges with S. aureus as a pathogen is its ability to acquire antibiotic resistance and produce robust biofilms. In this work, we investigated the nature of the cell wall defect in the msaABCR operon mutant in the Mu50 (VISA) and USA300 LAC methicillin-resistant Staphylococcus aureus (MRSA) strains. Results showed that msaABCR-mutant cells had decreased cell wall thickness and cell wall crosslinking in both strains. These defects are most likely due to increased murein hydrolase activity and/or nonspecific processing of murein hydrolases mediated by increased …

Increasing Antibiotic Resistance In Shigella Bacteria In The United States, William J. Pharr

The Corinthian

Shigella bacteria cause half a million infections, 6,000 hospitalizations, and 70 deaths annually in the United States. These bacteria are of particular concern due to their high survivability, low infectious dose, and high adaptability. Cases of shigellosis from Shigella sonnei are becoming a more prevalent issue in the U.S. as the bacteria continues to develop higher resistance to today’s strongest antibiotics. Much of this resistance is connected to the exchange of genes between strains of Shigella due to insertion sequences (IS), intercontinental travel, and men who have sex with men (MSM). As a result of increased resistance, the use of …

The Effects Of Farnesol, A Quorum Sensing Molecule From Candida Albicans, On Alcaligenes Faecalis, Savannah Hutson

Undergraduate Honors Theses

Quorum sensing molecules have become a recent focus of study to learn if and how they can be used, both on their own and in conjecture with current antimicrobial methods, as a means of bacterial control. One such quorum sensing molecule is the sesquiterpene alcohol, Farnesol, which is synthesized and released by the fungus, Candida albicans. In most in-vivo cases, our laboratory has shown that Alcaligenes faecalis overtakes C. albicans, preventing its growth. However, as a way to counteract this inhibitory effect, Farnesol may be one way that Candida has found to fight back. In this study, we …

Characterization Of The Broad-Spectrum Inhibitory Capability Of Alcaligenes Faecalis And A. Viscolactis Against Potential Pathogenic Microorganisms, Andrew Fuqua

Undergraduate Honors Theses

The recent rise of multidrug resistant microorganisms has grown from an isolated concern to a massive public health crisis. It has become imperative that scientists look for new ways to combat this issue. Due to the selective pressures of competition, bacteria and other microbes possess a host of defenses and weapons designed to exploit vulnerabilities in other microorganisms. Consequently, the study of these systems and microbial interactions has much to reveal in the search for novel antimicrobial treatments. Previous research from our laboratory has discovered that both Alcaligenes faecalis and Alcaligenes viscolactis, two rarely studied and generally non-virulent bacteria, …

Antibiotic Resistant Bacteria, Antibiotic Resistance Genes And Potential Drivers In The Aquatic Environments, Shuo Shen

Dissertations

As antibiotic resistance genes in aquatic environment have been increasing across the world, affecting water quality and public health, many studies documented concentrations of antibiotic resistance genes and some studies discussed their potential drivers. However, systematic and quantitative reviews that link antibiotic resistance genes (ARGs) to anthropogenic and environmental factors are limited. Nevertheless, this information will be important for developing regulation policy on controlling antibiotic use and therefore reducing potential risks to antibiotic resistance. I conducted meta-analysis of ARGs concentration at a global scale using Bayesian inference to explore climatic and socio-economic factors as drivers. I found local-scale climatic variables …

Identification Of Antibiotic Producing Soil Bacteria Against Bacillus Subtilis, Morgan Brockhouse, Dr. Lori Scott

Identifying and Characterizing Novel Antibiotic Producing Microbes From the Soil

This project is a collaboration with the Tiny Earth Project Initiative (TEPI), which is a global network of educators and students focused on student-sourcing antibiotic discovery from soil. Individual strains of soil bacteria were isolated and produced antibiotic against Bacillus subtilis. Two of these samples were sequenced using the 16S rRNA gene to reveal they are very closely related to the genus Pseudomonas.

Assessing The Prevalence Of Multidrug Resistant Salmonella Enterica From Stream Sediment And Poultry Litter In The Shenandoah Valley Of Virginia, Noah Greenman

Masters Theses, 2010-2019

Multidrug resistant Salmonella enterica present in stream sediment and poultry litter represent a critical health concern. A small number of S. enterica serotypes are responsible for most lab-confirmed infections in the US each year. To assess the prevalence of these significant strains, we isolated 88 S. enterica from stream sediment and poultry litter. Sequence data for all isolates were generated using an Illumina® sequencing platform, with long-reads for some isolates from the Oxford Nanopore MinION™ used in a hybrid genome assembly approach. Isolates were typed according to their serotype and multi-locus sequence type using SeqSero/SISTR and Enterobase respectively. Antibiotic resistance …