Pathogenic Microbiology Commons^™

Characterization Of Staphylococcus Aureus Clinical Isolates From Deep Musculoskeletal Infections For An In Vitro Biofilm Model For Phage Therapy, Raquel C. Luna

Dissertations and Theses (Open Access)

The rise of multidrug-resistant (MDR) infections is a growing concern in the treatment of deep musculoskeletal infections (MSKIs) and orthopaedic device-related infections (ODRIs). Staphylococcus aureus is responsible for about one third of these infections due to its strong biofilm forming capacity, presence on human skin, and the large number of antibiotic-resistant variants. Bacteriophage (phage) therapy is now being considered as a treatment for MDR MSKIs/ODRIs. We are investigating the use of phage encapsulated into or adsorbed onto biodegradable microspheres for local delivery to the site of these MDR infections. We determined that the anti-staphylococcal phage K effectively lyses the S. …

Elucidation Of A Role In Biofilm Production For The Tyrosine Catabolism Pathway In Vibrio Cholerae And Analysis Of Reversible Phase Variation In Vibrio Vulnificus, Aheli S. Mukerji

LSU Doctoral Dissertations

Biofilms produced by the cholera pathogen Vibrio cholerae not only enhance its ability to survive in the environment but also allow pathogenic success of the bacterium. This organism also undergoes phase variation, switching between smooth and rugose colonial phenotypes, the latter forming much more vibrio polysaccharide (VPS) resulting in more robust biofilms and subsequently having an increased level of persistence. In a previous study, many genes were found to be upregulated in the transition from the smooth to the rugose phenotype. Here, several of these upregulated genes were investigated for their potential role in biofilm production, and an additional gene, …

Antibiotic-Induced Changes In Efflux Transporter Expression: A Key Factor In Pseudomonas Aeruginosa Biofilm Resistance, Zara Imtiaz, Avinash Chatoo, Will Wang, Weiqi Li, Paramita Basu

Touro College of Pharmacy (New York) Publications and Research

Listed by WHO as an antibiotic-resistant priority pathogen, Pseudomonas aeruginosa(P.A.) is a serious threat in nosocomial infections. Its high antibiotic resistance is attributed to major mechanisms that can be categorized into intrinsic, acquired, and adaptive resistance. This study tests the ability of three commonly used antibiotics to inhibit new biofilm formation and eradicate mature biofilm growth, as well as investigate changes in the expression levels of selected genes coding for multidrug efflux pumps in P.A. planktonic cells and biofilms before and after treatment with antibiotics to provide a conceptual estimate of the activity of the efflux transporters that work to …

Reiq-Mediated Alarmone Signalling Regulates Growth, Stress-Induced Biofilm Formation And Spore Accumulation In Clostridioides Difficile, Areej Malik, Adenrele Oludiran, Asia Poudel, Orlando Berumen Alvarez, Charles Woodward, Erin B. Purcell

Chemistry & Biochemistry Faculty Publications

The bacterial stringent response (SR) is a conserved transcriptional reprogramming pathway mediated by the nucleotide signalling alarmones, (pp)pGpp. The SR has been implicated in antibiotic survival in Clostridioides difficile, a biofilm- and spore-forming pathogen that causes resilient, highly recurrent C. difficile infections. The role of the SR in other processes and the effectors by which it regulates C. difficile physiology are unknown. C. difficile RelQ is a clostridial alarmone synthetase. Deletion of relQ dysregulates C. difficile growth in unstressed conditions, affects susceptibility to antibiotic and oxidative stressors and drastically reduces biofilm formation. While wild-type C. difficile displays increased biofilm …

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. …

Identification And Characterization Of Genetic Elements That Regulate A C-Di-Gmp Mediated Multicellular Trait In Pseudomonas Fluorescens, Collin Kessler

Electronic Theses and Dissertations

Microbial communities contain densely packed cells where competition for space and resources are fierce. These communities are generally referred to as biofilms and provide advantages to individual cells against immunological and antimicrobial intervention, dehydration, and predation. High intracellular pools of cyclic diguanylate monophosphate (c-di-GMP) cause cells to aggregate during biofilm formation through the production of diverse extracellular polymers. Genes that encode c-di-GMP catalytic enzymes are commonly mutated during chronic infections where opportunists display enhanced resistance to phagocytosis and antibiotics. Our lab uses an emergent multicellular trait in the model organism Pseudomonas fluorescens Pf0-1 to study the emergence of c-di-GMP mutations …

The Role Of L-Alanine Signaling In Aspergillus Fumigatus Biofilm Adherence, Carbon Catabolism, And Echinocandin Susceptibility., Joshua D. Kerkaert

Dartmouth College Ph.D Dissertations

Aspergillus fumigatus is a saprophytic filamentous fungus that participates in environmental carbon and nitrogen cycles through the degradation of complex organic substrates. In addition to its ecological role, A. fumigatus is the primary causative agent of a spectrum of diseases depending on the immune status of the individual, the most lethal of which is invasive aspergillosis (IA). Treatment strategies for IA are limited and far too frequently fail. Despite the high rates of treatment failure, antifungal resistance remains relatively low, albeit rising at a concerning rate. Insights into this discrepancy between the rate of treatment failure and the rate of …

Identification Of Pneumococcal Membrane Proteins Involved In Colonization/Biofilm Formation And Cognate Host Cellular Receptors, Yoonsung Hu

Theses and Dissertations

Colonization is prerequisite for infection and transmission of Streptococcus pneumoniae, or pneumococcus. Currently available pneumococcal conjugate and pneumococcal polysaccharide vaccines can provide protection against a limited number of capsular serotypes. Implementation of vaccines has decreased the frequency of invasive pneumococcal disease and their colonization rates, but only in a serotype-dependent manner. This has led to serotype replacement in pneumococcal ecology and increased invasive disease caused by non-vaccine serotypes. Development of conserved protein-based vaccine that can provide protection against all pneumococcal serotypes is needed. Numerous surface proteins are conserved in all serotypes, and some are known to be involved in …

Periodic Spatial Disturbances Alter The Expression Of Quorum Sensing Virulence Factors In Pseudomonas Aeruginosa, Laura García-Diéguez

All HCAS Student Capstones, Theses, and Dissertations

Pseudomonas aeruginosa is an opportunistic pathogen associated with severe acute and chronic illnesses. Current antibiotic-based approaches fail to effectively treat P. aeruginosa infections due to the effectiveness and robustness of the quorum sensing signaling system (QS). Pathogenic bacteria, such as P. aeruginosa, employ this population density-dependent communication mechanism to confer antimicrobial resistance, propagate infection, and coordinate the expression of virulence factors, through the production and detection of autoinducing signaling molecules (AI). As such, there is a growing interest in developing novel non-antibiotic-based techniques to attenuate the pathogenicity of P. aeruginosa by disrupting the functionality of its QS system. Previous …

Increasing The Frequency Of Periodic Spatial Disturbance Decreases Surface Attachment Protein Expression In Staphylococcus Aureus, Ivana M. Barraza

All HCAS Student Capstones, Theses, and Dissertations

Staphylococcus aureus is an opportunistic pathogen that can cause a variety of acute and chronic illnesses. The severity of these illnesses such as sepsis, necrotizing pneumonia, and toxic shock syndrome is measured through the virulence that S. aureus inflicts on its host. Methicillin-resistant S. aureus (MRSA) is commonly associated with secondary infections and is challenging to treat given the limited selection of antibiotics that are effective against it. Accordingly, novel approaches to reduce S. aureus pathogenicity are required. S. aureus regulates pathogenesis through a cell-to-cell communication system referred to as quorum sensing. Effective communication determines the production of two broad …

Biofilm Associated Staphylococcus Aureus Viability Is Altered By Burkholderia Cenocepacia, Bridget Wall, Tiffany J. Brandt, Dr. Deborah Yoder-Himes

Undergraduate Arts and Research Showcase

Respiratory failure caused by chronic and recurrent microbial infections is the most common cause of death for people with cystic fibrosis (CF)¹, a disease causing the formation of thick mucus in the lungs². Most bacteria can form biofilms, collections of sessile cells adhered to a surface by a secreted substance. Biofilm-associated cells develop antibiotic resistance at higher rates³. The thicker mucus in CF lungs is extremely difficult to clear via action of the mucociliary escalator and its presence fosters the formation of bacterial biofilms. Staphylococcus aureus and Burkholderia cenocepacia are two pathogens commonly found …

Phenotypic And Transcriptomic Characterization Of Colonial Phase Variation In The Cholera Pathogen Reveals A Novel Smooth Biofilm-Defective Form, Bliss Nicole Lambert

LSU Doctoral Dissertations

Biofilm formation, through the production of Vibrio polysaccharide (VPS), greatly enhances the environmental fitness and pathogenic success of Vibrio cholerae. As a result of phase variation, V. cholerae can switch from a smooth form to rugose, whose cells produce excess VPS, resulting in highly structured biofilms and greater resistance to stress. To further characterize the reversible process of phase variation, we isolated three colonial lineages. Each lineage began with a smooth parent, N16961, and contained a rugose variant derived from the parent, N16961R, as well as a smooth revertant of the rugose, N16961SD. We found clear phenotypic and transcriptomic …

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 …

The Antimicrobial And Biofilm Disruption Activity Of Novel Amphiphiles, Elizabeth A. Rogers

Masters Theses, 2010-2019

Antibiotic resistant infections are responsible for approximately 23,000 deaths every year in the United States alone. The formation of bacterial biofilms makes resistant bacteria difficult to eliminate completely using chemical treatment. Therefore, novel antimicrobial compounds such as amphiphiles are essential to slow or stop the spread of resistant bacteria. Several novel series of amphiphiles were synthesized, and discrete aspects of their chemical structure were altered to investigate the relationship between structure and antibacterial activity. Minimum inhibitory concentration (MIC) assays were used to measure antibacterial activity against two Gram-negative and five Gram-positive bacteria, and the most effective compounds were tested for …

Determination Of The Effects That A Previously Uncharacterized Secreted Product From Klebsiella Pneumoniae Has On Citrobacter Freundii And Enterobacter Cloacae Biofilms, Cody M. Hastings

Undergraduate Honors Theses

More so than ever, Multiple Drug Resistant (MDR) bacteria are on the rise due to overuse of antibiotics along with natural selection for adaptations that enhance drug-resistant properties. One particular bacterial family, Enterobacteriaceae, has been problematic, exhibiting several bacterial members that have developed a precipitous resistance to modern antibiotics and are also primary causative agents of nosocomial, or hospital acquired, infections. Citrobacter freundii (CF) and Enterobacter cloacae (ECL) are two species of the Enterobacteriaceae family causing significant medical concern due to their role in producing numerous opportunistic infections such as bacteremia, lower respiratory tract infections, urinary tract infections, and endocarditis. …

Controlling Brochothrix Thermosphacta As A Spoilage Risk Using In Package Atmospheric Cold Plasma, Apurva Patange, Daniela Boehm, Carmen Bueno-Ferrer, Patrick J. Cullen, Paula Bourke

Articles

Brochothrix thermosphacta is a predominant spoilage microorganism in meat and its control in processing environments is important to maintain meat product quality. Atmospheric cold plasma is of interest for control of pathogenic and spoilage microorganisms in foods. This study ascertained the potential of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) for control of B. thermosphacta in response to key parameters such as treatment time, voltage level, interactions with media composition and post treatment storage conditions. Challenge populations were evaluated as suspensions in PBS, as biofilms in meat model medium and surface attached on raw lamb chops under MAP.

ACP treatment …

Fluid Dynamic Factors As A Cause And Effect Of Biofilm Formation Of Staphylococcus Aureus Biofilms, Erica Sherman

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Staphylococcus aureus bacteria are able to form biofilms and distinctive tower structures that facilitate their ability to tolerate treatment and to spread within the human body. The formation of towers, which break off, get carried downstream and serve to initiate biofilms in other parts of the body are of particular interest here. It is known that flow conditions play a role in the development, dispersion and propagation of biofilms. The influence of flow on tower formation and what factors lead to tower formation is not at all understood The hypothesis being examined is that tower structures form within a specific …

The Effect Of Antibiotics On Pseudomonas Aeruginosa Biofilm Production, Courtney Paige Turpin

Online Theses and Dissertations

Antibiotic-resistant bacteria have become an increasing burden worldwide. A highly resistant species is Pseudomonas aeruginosa, a nosocomial pathogen that produces a biofilm that enhances its resistance. This project examined the possibility of using bacteriocin, an internal protective toxin produced by some species of bacteria, as a potential treatment for resistant bacteria. In this study, standard broad spectrum antibiotics were used to treat P. aeruginosa to prevent biofilm formation. The biofilm was then analyzed to determine if the biofilm is inhibited or facilitated by each treatment. Optimal concentrations of antibiotics were determined to be effective at a concentration of 0.07mg/mL for …

Purification And Characterization Of Bcsc; An Integral Component Of Bacterial Cellulose Export, Emily D. Wilson Ms

Theses and Dissertations (Comprehensive)

Biofilms are a growing concern in the medical field due to their increased resistance to antibiotics. When found in a biofilm, bacteria can have antibiotic resistance 10-1000 times that of their planktonic counterparts. Therefore, it is important to study the formation of biofilms. Cellulose biofilms are formed by Enterobacteriaceae, such as many Escherichia coli and Salmonella spp. strains. Biofilms provide these species with benefits including antimicrobial protection, development of bacterial communities, promotion of DNA exchange, uptake of nutrients, and, in the case of cellulose biofilms, immune system evasion. Cellulose biofilms are controlled by the Bacterial cellulose synthesis (Bcs) complex located …