Medical Microbiology Commons^™

Infection Potential Of Rickettsia Felis Via Ingestion, Matthew M. Schexnayder

LSU Master's Theses

Rickettsia felis is the etiologic agent of flea-borne spotted fever (FBSF) in humans and a poorly described cause of fever in animals. It is transmitted by its primary arthropod vector and reservoir host, the cat flea Ctenocephalides felis. Known routes of Rickettsia felis transmission between Rickettsia felis-infected cat fleas and vertebrate hosts include cutaneous bites and contamination of cutaneous wounds with infective flea feces. The bulk of FBSF infections occur in young children in Africa, though infections of people at all ages all over the world have been confirmed. As mammals and young children frequently come into contact …

Monocyte Anti-Inflammatory Activity Is Dictated By Metabolic Status During Staphylococcus Aureus Biofilm Infection, Kelsey J. Yamada

Theses & Dissertations

Staphylococcus aureus biofilms represent a significant cause of morbidity and economic burden and are often associated with nosocomial infections, including medically implanted devices. In particular, prosthetic joint infections (PJIs) are a growing concern due to the continued increase in orthopedic procedures. Staphylococcal species cause >50% of all PJIs, while S. aureus represents the most invasive and associated with the most morbidity. S. aureus-associated biofilm infections are recalcitrant to antibiotic therapy, due to both the acquisition of genetic elements and metabolic dormancy. Furthermore, S. aureus biofilm infections remain chronic because they cannot be cleared by the immune system. Recent studies …

Identification Of Anaerobes In Clinical Specimens Comparison Between The Rapid Ana Ii System And The Bruker Maldi-Tof Ms System Utilized In The Clinical Laboratory, Raymond Chow

Natural Sciences and Mathematics | Clinical Laboratory Sciences

Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has been revealed as an invaluable platform for identifying anaerobic bacteria in the clinical laboratory over traditional methods such as the RapID ANA II System.

A qualitative comparison is made, through the analysis of methodologies and specifications, to determine whether the RapID ANA II system or Bruker MALDI-TOF MS is more suitable for identifying anaerobic organism in the clinical laboratory. Based on the data reviewed, the MALDI-TOF MS is a more intuitive platform within the clinical laboratory due to its increased specificity, cost-effectiveness, and shorten turnaround time for the identification …

Development Of Methods To Evaluate The Use Of Medi-551 To Target Cd19 Transmembrane Proteins On B-Cells To Improve Systemic Sclerosis, Natalia Dohman

Honors Thesis

Systemic sclerosis, a subcategory of scleroderma, is a rare autoimmune disease that affects the skin and, in some cases, the internal organs of those diagnosed with the disease. There is currently no cure for this disease, only treatments to slow its progression. It is important to note that each individual diagnosed with scleroderma experience differences in severity and symptoms of the disease and are treated based on their symptoms, not as a whole. Many factors of this disease still remain unknown, such as what causes the disease or stimulates the onset of it. Recent studies have helped determine different treatment …

Effects Of Ambient And Laser Light On Water Evaporation From The Surface Of Polyurethane Swabs Doped With Surfactant, Collin Campbell

Chemical Engineering Undergraduate Honors Theses

Polyurethane swabs are a common instrument for environmental sampling in the food, medical, and forensic fields due to their high recovery of organisms like viruses, spores, and bacteria. For sampling microbes in food and medical facilities, storage of the collected samples occurs under the absence of light to promote growth for more accurate testing. In the forensic fields, microbial growth results in sample contamination so the inhibition of this growth requires the drying of the swabs. This work studies the evaporation rates of water from polyurethane swabs under zero watt incident light, 30 W fluorescent bulb, 50 mW 532 nm …

Role Of Atm In T Cell Dysfunction During Chronic Viral Infections, Juan Zhao

Electronic Theses and Dissertations

Hepatitis C virus (HCV) or human immunodeficiency virus (HIV) infection leads to a phenomenon of inflammaging, in which chronic infection or inflammation induces an immune aged phenotype with T cell dysfunction. Thus, HCV or HIV infection has been deemed as a model to study the mechanisms of T cell infammaging and viral persistence in humans. In this dissertation, T cell homeostasis, DNA damage and repair machineries were investigated in patients with chronic HCV or HIV infection at risk for inflammaging. We found a significant depletion in CD4 T cells, which was correlated with their apoptosis in chronically HCV/HIVinfected patients, compared …

Transcriptional Regulation Of Nlrc4 Inflammasome By Irf8, Ein Lee

Theses and Dissertations (ETD)

The NLRC4 inflammasome is a crucial part of the innate immune response against bacterial infections. We found that NLRC4 inflammasome activation in bone marrow-derived macrophages (BMDMs) is greatly dependent on interferon regulatory factor 8 (IRF8). NLRC4-mediated caspase-1 activation and subsequent production of the inflammasome-dependent cytokines IL-1β and IL-18 and cell death were impaired in IRF8-deficient cells. IRF8 mediated the transcription of genes encoding NAIPs, the receptors for NLRC4 inflammasome, which recognize bacterial flagellin and type III secretion system (T3SS) proteins. IRF8 was critical for host survival following infection with Salmonella Typhimurium or Burkholderia thailandensis. Furthermore, mice deficient in IRF8 were …

Rabies-Based Vaccine Induces Potent Immune Responses Against Nipah Virus., Rohan Keshwara, Thomas Shiels, Elena Postnikova, Drishya Kurup, Christoph Wirblich, Reed F. Johnson, Matthias J. Schnell

Department of Microbiology and Immunology Faculty Papers

Nipah Virus (NiV) is a re-emerging zoonotic pathogen in the genus Henipavirus of the Paramyxoviridae family of viruses. NiV is endemic to Bangladesh and Malaysia and is highly fatal to both livestock and humans (human case fatality rate = 74.5%). Currently, there is no approved vaccine against NiV on the market. The goal of this study was to use a recombinant RABV vector expressing NiV glycoprotein (NiV G) to develop a bivalent candidate vaccine against NiV disease and rabies virus (RABV) disease, which is also a significant health burden in the regions where NiV is endemic. The rabies vector is …

Role Of Ribosome Recycling Factor As A Ribosome Releasing Factor, Yoshio Inokuchi, Fabio Quaglia, Akikazu Hirashima, Yoshihiro Yamamoto, Hideko Kaji, A. Kaji

Department of Biochemistry and Molecular Biology Posters

The objective of this presentation is to study the in vivo actions of ribosome recycling factor (RRF) and compare them with those found in vitro. RRF is known to catalyze three separate reactions: release of tRNA and mRNA from the post-termination complex (PoTC), and splitting of the ribosome of the PoTC. To study the mechanism of RRF reaction in vivo, we used E. coli harboring temperature sensitive (ts) RRF and assayed by following downstream reading of translationally coupled ORF. At the non-permissive temperature, ribosomes remain on the termination codon of the junction sequence of coupled ORFs and translate downstream ORF …

Induction Of Lipid Bodies In Leishmania Infantum-Infected C57bl/6 Macrophages Of Male Versus Female Origin, Victor A. Soupene, Ryan D. Lockard, Mary E. Wilson, Nilda E. Rodriguez

Research in the Capitol

Worldwide, 12 million people are infected with Leishmania spp. parasites. Leishmania are transmitted by the bite of sand flies. The parasite is internalized by immune cells where they develop, reproduce, and spread to new immune cells causing disease. Epidemiological studies have shown that males are more likely to develop disease. We recently demonstrated that Leishmania infantum survive better in immune cells of male origin than in cells derived from females. We also showed that L. infantum infection is characterized by fat accumulation. Additional experiments have shown that infected immune cells from males accumulate more fat than cells from females. We …

Long-Term Use Of Antibiotics And Risk Of Colorectal Adenoma, Yin Cao, Kana Wu, Raaj Mehta, David A. Drew, Mingyang Song, Paul Lochhead, Long H. Nguyen, Jacques Izard, Charles S. Fuchs, Wendy S. Garrett, Curtis Huttenhower, Shuji Ogino, Edward L. Giovannucci, Andrew T. Chan

Department of Food Science and Technology: Faculty Publications

Objective: Recent evidence suggests that antibiotic use, which alters the gut microbiome, is associated with an increased risk of colorectal cancer. However, the association between antibiotic use and risk of colorectal adenoma, the precursor for the majority of colorectal cancers, has not been investigated.

Design: We prospectively evaluated the association between antibiotic use at age 20–39 and 40–59 (assessed in 2004) and recent antibiotic use (assessed in 2008) with risk of subsequent colorectal adenoma among 16,642 women aged ≥ 60 enrolled in the Nurses’ Health Study who underwent at least one colonoscopy through 2010. We used multivariate logistic …

Dynamic Molecular Changes During The First Week Of Human Life Follow A Robust Developmental Trajectory., Amy H. Lee, Casey P. Shannon, Nelly Amenyogbe, Tue B. Bennike, Joann Diray-Arce, Olubukola T. Idoko, Erin E. Gill, Rym Ben-Othman, William S. Pomat, Simon D. Van Haren, Kim-Anh Lê Cao, Momoudou Cox, Alansana Darboe, Reza Falsafi, Davide Ferrari, Daniel J. Harbeson, Daniel He, Cai Bing, Samuel J. Hinshaw, Jorjoh Ndure, Jainaba Njie-Jobe, Matthew A. Pettengill, Peter C. Richmond, Rebecca Ford, Gerard Saleu, Geraldine Masiria, John Paul Matlam, Wendy Kirarock, Elishia Roberts, Mehrnoush Malek, Guzmán Sanchez-Schmitz, Amrit Singh, Asimenia Angelidou, Kinga K. Smolen, Diana Vo, Ken Kraft, Kerry Mcenaney, Sofia Vignolo, Arnaud Marchant, Ryan R. Brinkman, Al Ozonoff, Robert E.W. Hancock, Anita H.J. Van Den Biggelaar, Hanno Steen, Scott J. Tebbutt, Beate Kampmann, Ofer Levy, Tobias R. Kollmann

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Systems biology can unravel complex biology but has not been extensively applied to human newborns, a group highly vulnerable to a wide range of diseases. We optimized methods to extract transcriptomic, proteomic, metabolomic, cytokine/chemokine, and single cell immune phenotyping data fromblood, a volume readily obtained from newborns. Indexing to baseline and applying innovative integrative computational methods reveals dramatic changes along a remarkably stable developmental trajectory over the first week of life. This is most evident in changes of interferon and complement pathways, as well as neutrophil-associated signaling. Validated across two independent cohorts of newborns from West Africa and Australasia, a …

Ripk1 Can Mediate Apoptosis In Addition To Necroptosis During Embryonic Development., Xuhua Zhang, John P. Dowling, Jianke Zhang

Department of Microbiology and Immunology Faculty Papers

RIPK1 has emerged as a key effector in programmed necrosis or necroptosis. This function of RIPK1 is mediated by its protein serine/threonine kinase activity and through the downstream kinase RIPK3. Deletion of RIPK1 prevents embryonic lethality in mice lacking FADD, a signaling adaptor protein required for activation of Caspase 8 in extrinsic apoptotic pathways. This indicates that FADD-mediated apoptosis inhibits RIPK1-dependent necroptosis to ensure successful embryogenesis. However, the molecular mechanism for this critical regulation remains unclear. In the current study, a novel mouse model has been generated, by disrupting a potential caspase cleavage site at aspartic residue (D)324 in RIPK1. …

Wave 2 Strains Of Atypical Vibrio Cholerae El Tor Caused The 2009-2011 Cholera Outbreak In Papua New Guinea, Andrew R. Greenhill, Ankur Mutreja, Dieter Bulach, Matthew J. Belousoff, Marinjho H. Jonduo, Deirdre A. Collins, Monalisa P. Kas, Johanna Wapling, Torsten Seemann, Alice Lafana, Gordon Dougan, Mark V. Brown, Paul F. Horwood

Research outputs 2014 to 2021

Vibrio cholerae is the causative agent of cholera, a globally important human disease for at least 200 years. In 2009-2011, the first recorded cholera outbreak in Papua New Guinea (PNG) occurred. We conducted genetic and phenotypic characterization of 21 isolates of V. cholerae, with whole-genome sequencing conducted on 2 representative isolates. The PNG outbreak was caused by an atypical El Tor strain harbouring a tandem repeat of the CTX prophage on chromosome II. Whole-genome sequence data, prophage structural analysis and the absence of the SXT integrative conjugative element was indicative that the PNG isolates were most closely related to strains …

Osteoblasts Are "Educated" By Crosstalk With Metastatic Breast Cancer Cells In The Bone Tumor Microenvironment., Alexus D. Kolb, Alison B. Shupp, Dimpi Mukhopadhyay, Frank C. Marini, Karen M. Bussard

Department of Cancer Biology Faculty Papers

INTRODUCTION: In a cancer-free environment in the adult, the skeleton continuously undergoes remodeling. Bone-resorbing osteoclasts excavate erosion cavities, and bone-depositing osteoblasts synthesize osteoid matrix that forms new bone, with no net bone gain or loss. When metastatic breast cancer cells invade the bone, this balance is disrupted. Patients with bone metastatic breast cancer frequently suffer from osteolytic bone lesions that elicit severe bone pain and fractures. Bisphosphonate treatments are not curative. Under ideal circumstances, osteoblasts would synthesize new matrix to fill in erosion cavities caused by osteoclasts, but this is not what occurs. Our prior evidence demonstrated that osteoblasts are …

Tradd Regulates Perinatal Development And Adulthood Survival In Mice Lacking Ripk1 And Ripk3., John P. Dowling, Mohamed Alsabbagh, Christina Del Casale, Zheng-Gang Liu, Jianke Zhang

Department of Microbiology and Immunology Faculty Papers

TRADD is an adaptor for TNFR1-induced apoptosis and NFκB activation. However, TRADD-deficient mice undergo normal development and contain normal lymphoid populations, which contrasts with an embryonic defect in mice lacking FADD, the shared adaptor mediating apoptosis. Recent studies indicate FADD suppresses embryonic necroptosis mediated by RIPK1. TRADD was suggested to also mediate necroptosis. Here we report that targeting TRADD fails to rescue Fadd ^−/− embryos from necroptosis, and ablation of TRADD rescues Ripk1 ^−/− mice from perinatal lethality when RIPK3-mediated necroptosis is disabled. The resulting Ripk1 ^−/− Ripk3 ^−/− Tradd ^−/− mice survive until early adulthood, but die thereafter. A …

Cyclin D1 Integrates G9a-Mediated Histone Methylation., Zhiping Li, Xuanmao Jiao, Gabriele Di Sante, Adam Ertel, Mathew C. Casimiro, Min Wang, Sanjay Katiyar, Xiaoming Ju, D. V. Klopfenstein, Aydin Tozeren, William Dampier, Iouri Chepelev, Albert Jeltsch, Richard G. Pestell

Department of Cancer Biology Faculty Papers

Lysine methylation of histones and non-histone substrates by the SET domain containing protein lysine methyltransferase (KMT) G9a/EHMT2 governs transcription contributing to apoptosis, aberrant cell growth, and pluripotency. The positioning of chromosomes within the nuclear three-dimensional space involves interactions between nuclear lamina (NL) and the lamina-associated domains (LAD). Contact of individual LADs with the NL are dependent upon H3K9me2 introduced by G9a. The mechanisms governing the recruitment of G9a to distinct subcellular sites, into chromatin or to LAD, is not known. The cyclin D1 gene product encodes the regulatory subunit of the holoenzyme that phosphorylates pRB and NRF1 thereby governing cell-cycle …

Severity Of Disease And Mortality For Hospitalized Patients With Community-Acquired Viral Pneumonia Compared To Patients With Community-Acquired Bacterial Pneumonia, Richard Y. Kim, Thomas Chandler, Stephen P. Furmanek, Timothy Lee Wiemken, Rodrigo Cavallazzi

The University of Louisville Journal of Respiratory Infections

Background: There exists a large body of literature to help identify, diagnose, treat, and manage community-acquired pneumonia (CAP). Despite this, there is little data that directly compares the clinical syndromes and complications of pure bacterial pneumonia to pure viral pneumonia. Our study compares the clinical presentation, morbidity and mortality of viral vs. bacterial etiologies of CAP.

Methods: This was a secondary data analysis of the Community-Acquired Pneumonia Organization (CAPO) international study database. Data was collected concerning patient demographics, physical examination findings, laboratory findings, radiological findings, severity of illness, and clinical outcomes and stratified according to the two study groups, CAVP …

Intranasal Peptide-Based Fpva-Klh Conjugate Vaccine Protects Mice From Pseudomonas Aeruginosa Acute Murine Pneumonia, Emel Sen-Kilic, Catherine B. Blackwood, Dylan T. Boehm, Wiliam T. Witt, Aaron C. Malkowski, Justin R. Bevere, Ting Y. Wong, Jesse M. Hall, Shelby D. Bradford, Melinda E. Varney, Fredrick Heath Damron, Mariette Barbier

Faculty & Staff Scholarship

Pseudomonas aeruginosa is an opportunistic pathogen causing acute and chronic respiratory infections associated with morbidity and mortality, especially in patients with cystic fibrosis. Vaccination against P. aeruginosa before colonization may be a solution against these infections and improve the quality of life of at-risk patients. To develop a vaccine against P. aeruginosa, we formulated a novel peptide-based P. aeruginosa subunit vaccine based on the extracellular regions of one of its major siderophore receptors, FpvA. We evaluated the effectiveness and immunogenicity of the FpvA peptides conjugated to keyhole limpet hemocyanin (KLH) with the adjuvant curdlan in a murine vaccination and challenge …

Protease-Mediated Growth Of Staphylococcus Aureus On Host Proteins Is Opp3 Dependent, Mckenzie K. Lehman, Austin S. Nuxoll, Kelsey J. Yamada, Tammy Kielian, Steven D. Carson, Paul D. Fey

Journal Articles: Pathology and Microbiology

Staphylococcus aureus has the ability to cause infections in multiple organ systems, suggesting an ability to rapidly adapt to changing carbon and nitrogen sources. Although there is little information about the nutrients available at specific sites of infection, a mature skin abscess has been characterized as glucose depleted, indicating that peptides and free amino acids are an important source of nutrients for the bacteria. Our studies have found that mutations in enzymes necessary for growth on amino acids, including pyruvate carboxykinase (ΔpckA) and glutamate dehydrogenase (ΔgudB), reduced the ability of the bacteria to proliferate within a …

Janus Kinase 1 Is Required For Transcriptional Reprograming Of Murine Astrocytes In Response To Endoplasmic Reticulum Stress, Savannah G. Sims, Gordon P. Meares

Faculty & Staff Scholarship

Neurodegenerative diseases are associated with the accumulation of misfolded proteins in the endoplasmic reticulum (ER), leading to ER stress. To adapt, cells initiate the unfolded protein response (UPR). However, severe or unresolved UPR activation leads to cell death and inflammation. The UPR is initiated, in part, by the transER membrane kinase PKR-like ER kinase (PERK). Recent evidence indicates ER stress and inflammation are linked, and we have shown that this involves PERKdependent signaling via Janus Kinase (JAK) 1. This signaling provokes the production of soluble inflammatory mediators such as interleukin-6 (IL-6) and chemokine C-C motif ligand 2 (CCL2). We, therefore, …

Endoplasmic Reticulum Stress Differentially Modulates The Il-6 Family Of Cytokines In Murine Astrocytes And Macrophages, Cristina L. Sanchez, Savnnah G. Sims, John D. Nowery, Gordon P. Meares

Faculty & Staff Scholarship

In many diseases, misfolded proteins accumulate within the endoplasmic reticulum (ER), leading to ER stress. In response, the cell initiates the unfolded protein response (UPR) to reestablish homeostasis. Additionally, in response to ER stress, various cell types mount an inflammatory response involving interleukin (IL)-6. While IL-6 has been widely studied, the impact of ER stress on other members of the IL-6 cytokine family, including oncostatin (OSM), IL-11, ciliary neurotrophic factor (CNTF), and leukemia inhibitor factor (LIF) remains to be elucidated. Here, we have examined the expression of the IL-6 family cytokines in response to pharmacologically-induced ER stress in astrocytes and …

Intranasal Acellular Pertussis Vaccine Provides Mucosal Immunity And Protects Mice From Bordetella Pertussis, Dylan T. Boehm, M. Allison Wolf, Jesse M. Hall, Ting Y. Wong, Emel Sen-Kilic, Hayden D. Basinger, Sebastian A. Dziadowicz, Maria De La Paz Gutierrez, Catherine B. Blackwood, Shelby D. Bradford, Katherine A. Begley, William T. Witt, Melinda E. Varney, Mariette Barbier, F. Heath Damron

Faculty & Staff Scholarship

Current acellular pertussis vaccines fall short of optimal protection against the human respiratory pathogen Bordetella pertussis resulting in increased incidence of a previously controlled vaccine- preventable disease. Natural infection is known to induce a protective mucosal immunity. Therefore, in this study, we aimed to use acellular pertussis vaccines to recapitulate these mucosal immune responses. We utilized a murine immunization and challenge model to characterize the efficacy of intranasal immunization (IN) with DTaP vaccine or DTaP vaccine supplemented with curdlan, a known Th1/Th17 promoting adjuvant. Protection from IN delivered DTaP was compared to protection mediated by intraperitoneal injection of DTaP and …

Bordetella Pertussis Can Be Motile And Express Flagellum-Like Structures, Cassandra L. Hoffman, Laura A. Gonyar, Federico Zacca, Federico Sisti, Julieta Fernandez, Ting Wong, F. Heath Damron, Erik L. Hewlett

Faculty & Staff Scholarship

ABSTRACT Bordetella bronchiseptica encodes and expresses a flagellar apparatus. In contrast, Bordetella pertussis, the causative agent of whooping cough, has historically been described as a nonmotile and nonflagellated organism. The previous statements that B. pertussis was a nonmotile organism were consistent with a stop codon located in the flagellar biosynthesis gene, flhA, discovered when the B. pertussis Tohama I genome was sequenced and analyzed by Parkhill et al. in 2003 (J. Parkhill, M. Sebaihia, A. Preston, L. D. Murphy, et al., Nat Genet, 35:32– 40, 2003, https://doi.org/10 .1038/ng1227). The stop codon has subsequently been found in all annotated genomes. Parkhill …

In Vivo Gene Essentiality And Metabolism In Bordetella Pertussis, Laura A. Gonyar, Patrick E. Gelbach, Dennis G. Mcduffe, Alexander F. Koeppel, Qing Chen, Gloria Lee, Louise M. Temple, Scott Stibitz, Erik L. Hewlwtt, Jason A. Papin, F. Heath Damron, Joshua C. Eby

Faculty & Staff Scholarship

Bordetella pertussis is the causative agent of whooping cough, a serious respiratory illness affecting children and adults, associated with prolonged cough and potential mortality. Whooping cough has reemerged in recent years, emphasizing a need for increased knowledge of basic mechanisms of B. pertussis growth and pathogenicity. While previous studies have provided insight into in vitro gene essentiality of this organism, very little is known about in vivo gene essentiality, a critical gap in knowledge, since B. pertussis has no previously identified environmental reservoir and is isolated from human respiratory tract samples. We hypothesize that the metabolic capabilities of B. pertussis …

Caspase-11 Mediates Neutrophil Chemotaxis And Extracellular Trap Formation During Acute Gouty Arthritis Through Alteration Of Cofilin Phosphorylation, Kyle Caution, Nicholas Young, Frank Robledo-Avila, Kathrin Krause, Arwa Abu Khweek, Kaitlin Hamilton, Asmaa Badr, Anup Vaidya, Kylene Daily, Hawin Gosu, Midhun N. K. Anne, Mostafa Eltobgy, Duaa Dakhlallah, Sudha Argwal, Shady Estfanous, Xiaoli Zhang, Santiago Partida-Sanchez, Mikhail A. Gavrilin, Wael N. Jarjour, Amal O. Amer

Faculty & Staff Scholarship

Gout is characterized by attacks of arthritis with hyperuricemia and monosodium urate (MSU) crystal-induced inflammation within joints. Innate immune responses are the primary drivers for tissue destruction and inflammation in gout. MSU crystals engage the Nlrp3 inflammasome, leading to the activation of caspase-1 and production of IL-1β and IL-18 within gout-affected joints, promoting the influx of neutrophils and monocytes. Here, we show that caspase-11−/− mice and their derived macrophages produce significantly reduced levels of gout-specific cytokines including IL-1β, TNFα, IL-6, and KC, while others like IFNγ and IL-12p70 are not altered. IL-1β induces the expression of caspase-11 in an IL-1 …

Identification Of Extracellular Dna-Binding Proteins In The Biofilm Matrix., Jeffrey S. Kavanaugh, Caralyn E. Flack, Jessica Lister, Erica B. Ricker, Carolyn B. Ibberson, Christian Jenul, Derek E. Moormeier, Elizabeth A. Delmain, Kenneth W. Bayles, Alexander R. Horswill

Journal Articles: Pathology and Microbiology

We developed a new approach that couples Southwestern blotting and mass spectrometry to discover proteins that bind extracellular DNA (eDNA) in bacterial biofilms. Using Staphylococcus aureus as a model pathogen, we identified proteins with known DNA-binding activity and uncovered a series of lipoproteins with previously unrecognized DNA-binding activity. We demonstrated that expression of these lipoproteins results in an eDNA-dependent biofilm enhancement. Additionally, we found that while deletion of lipoproteins had a minimal impact on biofilm accumulation, these lipoprotein mutations increased biofilm porosity, suggesting that lipoproteins and their associated interactions contribute to biofilm structure. For one of the lipoproteins, SaeP, we …

Reanalysis Of The Nccn Pd-L1 Companion Diagnostic Assay Study For Lung Cancer In The Context Of Pd-L1 Expression Findings In Triple-Negative Breast Cancer, David L. Rimm, Gang Han, Janis M. Taube, Eunhee S. Yi, Julia A. Bridge, Douglas B. Flieder, Robert Homer, Anja C. Roden, Fred R. Hirsch, Ignacio I. Wistuba, Lajos Pusztai

Journal Articles: Pathology and Microbiology

The companion diagnostic test for checkpoint inhibitor immune therapy is an immunohistochemical test for PD-L1. The test has been shown to be reproducible for expression in tumor cells, but not in immune cells. Immune cells were used in the IMpassion130 trial which showed PD-L1 expression was associated with a better outcome. Two large studies have been done assessing immune cell PD-L1 expression in lung cancer. Here, we reanalyze one of those studies, to show that, even with an easier scoring method, there is still only poor agreement between assays and pathologist for immune cell PD-L1 expression.

Observations Of Shear Stress Effects On Staphylococcus Aureus Biofilm Formation, Erica Sherman, Kenneth W. Bayles, Derek E. Moormeier, Jennifer L. Endres, Timothy Wei

Journal Articles: Pathology and Microbiology

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

Urease Is An Essential Component Of The Acid Response Network Of Staphylococcus Aureus And Is Required For A Persistent Murine Kidney Infection, Chunyi Zhou, Fatema Bhinderwala, Mckenzie K. Lehman, Vinai Chittezham Thomas, Sujata S. Chaudhari, Kelsey J. Yamada, Kirk W. Foster, Robert Powers, Tammy Kielian, Paul D. Fey

Journal Articles: Pathology and Microbiology

Staphylococcus aureus causes acute and chronic infections resulting in significant morbidity. Urease, an enzyme that generates NH3 and CO2 from urea, is key to pH homeostasis in bacterial pathogens under acidic stress and nitrogen limitation. However, the function of urease in S. aureus niche colonization and nitrogen metabolism has not been extensively studied. We discovered that urease is essential for pH homeostasis and viability in urea-rich environments under weak acid stress. The regulation of urease transcription by CcpA, Agr, and CodY was identified in this study, implying a complex network that controls urease expression in response to changes in metabolic …