Microbiology Commons^™

Antibiotic Resistance Patterns In Bacterial Isolates From Mississippi Gulf Coastal Environments, Lawler F. Horn

Honors Theses

Coastal environments host diverse microbial communities that play essential ecological roles but may also serve as reservoirs for antibiotic-resistant bacteria. This study investigated patterns of antibiotic resistance in microbial isolates collected from public beaches along the Mississippi Gulf Coast. A total of 143 bacterial isolates exhibited growth and were included in antibiotic susceptibility screening. High levels of antibiotic resistance were observed, with 137 of 143 isolates showing growth on vancomycin, 124 on amoxicillin, and 102 on erythromycin. Resistance to kanamycin (19/143 isolates) and tetracycline (33/143) was less common. Multidrug resistance was widespread, with 101 isolates (70.6%) resistant to three or …

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 …

Analysis Of Bacterial Virulence And Resistance In A Model Of Recurrent Uti, Rachel L. Proper

Undergraduate Honors Theses

Urinary tract infection (UTI) is a major women’s health issue, affecting approximately 40% of women during their lifetime. Formation of a biofilm by UTI-causing bacteria poses a major challenge in treatment, as the protection provided by the biofilm hinders both host defenses and antibiotic treatment. Failure to eradicate these infections causes them to become recurrent (rUTI). Previous research indicates that rUTI may be comorbid with a mutation in the SERPINE1 gene, which causes fibrin to accumulate within the body. Literature also indicates that fibrin provides a better scaffold for bacterial attachment and, subsequently, biofilm formation. In this work it was …

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 …

Emergence Of Heterogeneity In Bacteria During Antibiotic Exposures, Mirjana Stevanovic

Dartmouth College Ph.D Dissertations

Bacterial populations exposed to antibiotics often exhibit phenotypic heterogeneity, with individual cells displaying distinct responses with fates ranging from survival to arrest or death. The emergence of this heterogeneity is largely driven by feedback mechanisms mediated by the interactions between antibiotic action, gene regulation, and cellular metabolism. These responses unfold in dynamic environments where conditions such as nutrient availability and drug concentration fluctuate over time and space. Yet, these complex interactions and their role in shaping population-level outcomes during drug responses remain poorly understood. Using tetracycline resistance in E. coli as a model system, this thesis focuses on how these …

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 …

Exploration Of Enterococcus Faecalis Bacteriophages Diversity: Comprehensive Phylogenetic Analysis And Discovery Isolation Of Enterococcus Faecalis Phage From A Soil Sample In South Florida, Hailey N. Jauernick

All HCAS Student Capstones, Theses, and Dissertations

Enterococcus faecalis is a commensal bacterium found in the gastrointestinal tract, oral cavity, and vagina of humans, which can transition to pathogenic states, leading to diverse infections. Many E. faecalis infections are becoming progressively challenging to treat, stemming from the lack of effective antibiotic therapies against its virulence factors, including biofilm formation and antibiotic resistance. Phage therapy emerges as a promising alternative, targeting bacteria with minimal impact on host flora. However, despite phages' ubiquitous presence and potential applications in medicine and biotechnology, their diversity and ecological niches are vastly understudied. Here, we investigated the diversity of sequenced E. faecalis phages …

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 …

Decreasing The Antibiotic Survival Of Multi-Drug Resistant Gram-Positive Organisms, Areej Malik

Biomedical Sciences Theses & Dissertations

Biofilm production plays a crucial role in bacterial antibiotic tolerance and novel approaches are needed to combat it. The stringent response (SR), activated by nucleotide alarmones (pp)pGpp, is crucial for bacterial transcriptional reprogramming. In Clostridioides difficile, the SR is implicated in antibiotic survival, contributing to infection recurrence. Despite its known roles in sporulation and biofilm production in other bacterial species, the broader influence of the SR on C. difficile physiology remains undiscovered. This study deletes the C. difficile SR gene relQ, revealing the pivotal role of RelQ in regulating SR-dependent phenotypes in this organism. The absence of RelQ …

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 …

Microbial Prevalence And Antibiotic Resistance Associated With Urban Food Production Systems, Nirosha Ruwani Amarasekara

Wayne State University Dissertations

Despite the increasing popularity of urban agriculture and farmers’ markets, there is a lack of scientific data on microbial prevalence and antibiotic resistance associated with this unique food production system. The overall goal of this research is to understand antibiotic resistance and microbial prevalence in soil and fresh produce associated with urban agriculture. Specifically, we aim to investigate ARG in association with resistance genes to metals and other compounds in urban agricultural soil as well as antibiotic resistome and Listeria contamination in fresh produce distributed in urban communities.

In the initial phase of this research, soil samples were collected from …

Persistence Of Wastewater-Associated Antibiotic Resistant Bacteria In River Microcosms, Aoife P. Mahaney

Theses and Dissertations

The spread of antibiotic-resistant bacteria (ARB) associated with wastewater is a significant environmental concern, but little is known about the persistence and proliferation of these organisms in receiving water bodies after discharge. To address this knowledge gap, we performed a series of microcosm experiments in which river water was amended with either untreated or treated wastewater, and the abundance of viable ciprofloxacin-, Bactrim-, and erythromycin-resistant bacteria was monitored for 72 hours.

Both types of wastewater amendments increased the initial abundance of ARB compared to microcosms containing only river water. The increase was greatest with untreated wastewater, but that effect decreased …

Probiotic Compounds Inhibit Staphylococcus Aureus Biofilm Formation, Reduce Virulence, & Improve Antibiotic Sensitivity, Kyle R. Leistikow

Dissertations (1934 -)

Multidrug-resistant (MDR) bacterial infections are a top five global public health threat, causing 2.8 million infections and 35,000 deaths annually in the US alone. Staphylococcus aureus is one of the most clinically important MDR pathogens in the world with infections leading to high rates of morbidity and mortality in both humans and animals. This bacterium's ability to form protective biofilms further complicates classical antibiotic interventions, highlighting the need for new therapeutics with novel mechanisms of action. The goal of this dissertation was to investigate antibiofilm mechanisms employed by probiotic bacteria to reduce S. aureus virulence and mitigate antimicrobial resistance evolution …

Roles For Mycobacterial Dinb2 In Frameshift And Substitution Mutagenesis, Pierre Dupuy, Shreya Ghosh, Allison Fay, Oyindamola Adefisayo, Richa Gupta, Stewart Shuman, Michael S. Glickman

Publications and Research

Translesion synthesis by translesion polymerases is a conserved mechanism of DNA damage tolerance. In bacteria, DinB enzymes are the widely distributed promutagenic translesion polymerases. The role of DinBs in mycobacterial mutagenesis was unclear until recent studies revealed a role for mycobacterial DinB1 in substitution and frameshift mutagenesis, overlapping with that of translesion polymerase DnaE2. Mycobacterium smegmatis encodes two additional DinBs (DinB2 and DinB3) and Mycobacterium tuberculosis encodes DinB2, but the roles of these polymerases in mycobacterial damage tolerance and mutagenesis is unknown. The biochemical properties of DinB2, including facile utilization of ribonucleotides and 8-oxo- guanine, suggest that DinB2 could be …

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 …

Using Nspefs To Sensitize Mrsa To Vancomycin Treatment, Areej Malik, Alexandra E. Chittams-Miles, Claudia Muratori, Erin B. Purcell

The Graduate School Posters

Staphylococcus aureus (S. aureus) is a biofilm-forming pathogen. S. aureus treatment is marked by the development of antibiotic resistance. The public health impact has increased since the emergence of methicillin-resistant S. aureus (MRSA), which has started to show intermediate resistance to vancomycin in MRSA. Nano-second pulse electric fields (nsPEFs) are low-energy and high-power electric pulses, which have been suggested to sensitize pathogens to antibiotics by creating transient pores in the cell membrane. Our combinatorial treatment includes nsPEF pre-treatment and vancomycin post-treatment of MRSA cells. Our results show that MRSA log phase cells had the highest susceptibility to vancomycin. …

The Persistence And Stabilization Of Auxiliary Genes In The Human Skin Virome, Ema H. Graham, Wesley A. Tom, Alison C. Neujahr, Michael Adamowicz, Jennifer Clarke, Joshua R. Herr, Samodha C. Fernando

Nebraska Center for Virology: Faculty Publications

Background The human skin contains a diverse microbiome that provides protective functions against environmental pathogens. Studies have demonstrated that bacteriophages modulate bacterial community composition and facilitate the transfer of host-specific genes, potentially influencing host cellular functions. However, little is known about the human skin virome and its role in human health. Especially, how viral-host relationships influence skin microbiome structure and function is poorly understood.

Results Population dynamics and genetic diversity of bacteriophage communities in viral metagenomic data collected from three anatomical skin locations from 60 subjects at five different time points revealed that cutaneous bacteriophage populations are mainly composed of …

Laboratory Practices And Antimicrobial Resistance In A Florida Hospital, Crispina Marie Sy-Trias

Walden Dissertations and Doctoral Studies

Antibiotic resistance is a health threat affecting millions of Americans. Microorganisms develop resistance to antibiotics, rendering them useless for treating infections. The purpose of this quantitative study was to assess the associations between sample processing time and antibiotic resistance and is based on the health belief model. A retrospective specimen tracking activity of data from November 2019 to November 2020 was obtained by random sampling of 246 bacterial cultures. One hundred ninety-six (80%) samples were processed on time, and 50 (20%) were delayed; 167 (68%) samples were determined to have the presence of antimicrobial resistance (AMR), and 79 (32%) with …

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 …

Connecting Antibiotic Resistance To The Environment (Care): Introducing A Novel Framework Integrating Chemical Cross-Resistance And Place-Based Engagement To The Blue Marsh Watershed In Reading, Pennsylvania, Jill Felker

Antioch University Dissertations & Theses

Antibiotic resistance is a serious health threat around the world. Millions of individuals are infected with antibiotic-resistant bacteria yearly, and thousands die from previously curable illnesses. Although antibiotic resistance occurs naturally, misuse of antibiotics accelerates the loss of their effectiveness. Public health campaigns focusing on antibiotic awareness have not effectively communicated and educated the public on this health crisis. New efforts to combat antibiotic resistance are urgently needed. This dissertation focuses on the ecological and public health components of antibiotic resistance research that must be addressed to decelerate antibiotic resistance. A new interdisciplinary theoretical framework was developed to Connect Antibiotic …