Medicine and Health Sciences Commons^™

Evaluation Of Stratified Antibiograms For Use In Laboratory And Antimicrobial Stewardship, Linsey Donner

Theses & Dissertations

Antibiograms are critical for choosing empiric antimicrobial therapy. Cumulative antibiograms, which aggregate susceptibility data, can mask differences within specific patient subsets or clinical syndromes. This dissertation was done to determine if antibiotic susceptibilities showed substantial differences when comparing stratified antibiograms to cumulative antibiograms.

Antibiotic susceptibility data was retrospectively obtained from Nebraska Medicine January 1, 2017 – December 31, 2019 for Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis. The University of Nebraska Medical Center’s web antibiogram clinical decision support tool was used to export the data. Bacteria-antibiotic susceptibility rates of stratified antibiograms …

Accumulation Of Succinyl Coenzyme A Perturbs The Methicillin-Resistant Staphylococcus Aureus (Mrsa) Succinylome And Is Associated With Increased Susceptibility To Beta-Lactam Antibiotics, Christopher Campbell, Claire Fingleton, Merve S. Zeden, Emilio Bueno, Laura A Gallagher, Dhananjay Shinde, Jong-Sam Ahn, Heather M. Olson, Thomas L. Fillmore, Joshua N. Adkins, Fareha Razvi, Kenneth W. Bayles, Paul D. Fey, Vinai Chittezham Thomas, Felipe Cava, Geremy C. Clair, James P. O'Gara

Journal Articles: Pathology and Microbiology

Penicillin binding protein 2a (PBP2a)-dependent resistance to β-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA) is regulated by the activity of the tricarboxylic acid (TCA) cycle via a poorly understood mechanism. We report that mutations in sucC and sucD, but not other TCA cycle enzymes, negatively impact β-lactam resistance without changing PBP2a expression. Increased intracellular levels of succinyl coenzyme A (succinyl-CoA) in the sucC mutant significantly perturbed lysine succinylation in the MRSA proteome. Suppressor mutations in sucA or sucB, responsible for succinyl-CoA biosynthesis, reversed sucC mutant phenotypes. The major autolysin (Atl) was the most succinylated protein in the proteome, …

The Prospect Of Nanoparticle Systems For Modulating Immune Cell Polarization During Central Nervous System Infection, Lee E. Korshoj, Wen Shi, Bin Duan, Tammy Kielian

Journal Articles: Pathology and Microbiology

The blood-brain barrier (BBB) selectively restricts the entry of molecules from peripheral circulation into the central nervous system (CNS) parenchyma. Despite this protective barrier, bacteria and other pathogens can still invade the CNS, often as a consequence of immune deficiencies or complications following neurosurgical procedures. These infections are difficult to treat since many bacteria, such as Staphylococcus aureus, encode a repertoire of virulence factors, can acquire antibiotic resistance, and form biofilm. Additionally, pathogens can leverage virulence factor production to polarize host immune cells towards an anti-inflammatory phenotype, leading to chronic infection. The difficulty of pathogen clearance is magnified by …

Clinical Consequences And Determinants Of False Positive Blood Cultures In Adult Hospitalized Patients, Sidra Liaquat

Theses & Dissertations

Blood cultures are the gold standard for detecting blood stream infections. However, in the US, 0.6-6% of all blood cultures get contaminated leading to adverse clinical outcomes such as unnecessarily prolonged hospital stay and antibiotic therapy. Using electronic medical records, we explored the clinical outcomes and patient-specific risk factors of contaminated blood cultures in an era where rapid blood culture testing was being utilized to provide blood culture results within hours. Rapid blood culture test results can help clinicians in early and more effective management of patients with contaminated blood cultures, thus improving clinical outcomes. We also studied the impact …

The Migration Of Carbapenem-Resistant Acinetobacter Baumannii From The Battlefields Of Iraq And Afghanistan To The Healthcare Facilities Of The Veterans Health Administration, Jeffery Rogers

Capstone Experience

Multidrug-resistant organisms (MDRO) pose a great threat to health across the globe. That threat is also felt in the Veterans Health Administration (VHA). Wounded warriors returning home from the battlefields of Iraq and Afghanistan may have brought with them MDROs, such as the bacterium Acinetobacter baumannii, as they have transitioned from military service into the VHA facilities. This study investigates the interconnectedness of military service in the Department of Defense (DoD) and a lifetime of care at VHA through a longitudinal tracking of a linked cohort of combat veterans with battlefield injuries and subsequent MDR infections of A. baumannii. …

Integrative Network Analyses Of Transcriptomics Data Reveal Potential Drug Targets For Acute Radiation Syndrome, Robert Moore, Bhanwar Lal Puniya, Robert Powers, Chittibabu Guda, Kenneth W. Bayles, David B. Berkowitz, Tomáš Helikar

Journal Articles: Pathology and Microbiology

Recent political unrest has highlighted the importance of understanding the short- and long-term effects of gamma-radiation exposure on human health and survivability. In this regard, effective treatment for acute radiation syndrome (ARS) is a necessity in cases of nuclear disasters. Here, we propose 20 therapeutic targets for ARS identified using a systematic approach that integrates gene coexpression networks obtained under radiation treatment in humans and mice, drug databases, disease-gene association, radiation-induced differential gene expression, and literature mining. By selecting gene targets with existing drugs, we identified potential candidates for drug repurposing. Eight of these genes (BRD4, NFKBIA, CDKN1A, TFPI, MMP9, …

Crosstalk Between Staphylococcus Aureus And Innate Immunity: Focus On Immunometabolism, Christopher M. Horn, Tammy Kielian

Journal Articles: Pathology and Microbiology

Staphylococcus aureus is a leading cause of bacterial infections globally in both healthcare and community settings. The success of this bacterium is the product of an expansive repertoire of virulence factors in combination with acquired antibiotic resistance and propensity for biofilm formation. S. aureus leverages these factors to adapt to and subvert the host immune response. With the burgeoning field of immunometabolism, it has become clear that the metabolic program of leukocytes dictates their inflammatory status and overall effectiveness in clearing an infection. The metabolic flexibility of S. aureus offers an inherent means by which the pathogen could manipulate the …

The Evolution And Future Of Targeted Cancer Therapy: From Nanoparticles, Oncolytic Viruses, And Oncolytic Bacteria To The Treatment Of Solid Tumors, Kyle M. Pierce, William R. Miklavcic, Kyle P. Cook, Mikayla Sweitzer Hennen, Kenneth W. Bayles, Michael A. Hollingsworth, Amanda E. Brooks, Jessica E. Pullan, Kaitlin M. Dailey

Journal Articles: Pathology and Microbiology

While many classes of chemotherapeutic agents exist to treat solid tumors, few can generate a lasting response without substantial off-target toxicity despite significant scientific advancements and investments. In this review, the paths of development for nanoparticles, oncolytic viruses, and oncolytic bacteria over the last 20 years of research towards clinical translation and acceptance as novel cancer therapeutics are compared. Novel nanoparticle, oncolytic virus, and oncolytic bacteria therapies all start with a common goal of accomplishing therapeutic drug activity or delivery to a specific site while avoiding off-target effects, with overlapping methodology between all three modalities. Indeed, the degree of overlap …

Immunopathogenesis Of Craniotomy Infection And Niche-Specific Immune Responses To Biofilm, Sharon D.B. De Morais, Gunjan Kak, Joseph P. Menousek, Tammy Kielian

Journal Articles: Pathology and Microbiology

Bacterial infections in the central nervous system (CNS) can be life threatening and often impair neurological function. Biofilm infection is a complication following craniotomy, a neurosurgical procedure that involves the removal and replacement of a skull fragment (bone flap) to access the brain for surgical intervention. The incidence of infection following craniotomy ranges from 1% to 3% with approximately half caused by Staphylococcus aureus (S. aureus). These infections present a significant therapeutic challenge due to the antibiotic tolerance of biofilm and unique immune properties of the CNS. Previous studies have revealed a critical role for innate immune responses …

Structure And Activity Of A Selective Antibiofilm Peptide Sk-24 Derived From The Nmr Structure Of Human Cathelicidin Ll-37, Yingxia Zhang, Jayaram Lakshmaiah Narayana, Qianhui Wu, Xiangli Dang, Guangshun Wang

Journal Articles: Pathology and Microbiology

The deployment of the innate immune system in humans is essential to protect us from infection. Human cathelicidin LL-37 is a linear host defense peptide with both antimicrobial and immune modulatory properties. Despite years of studies of numerous peptides, SK-24, corresponding to the long hydrophobic domain (residues 9–32) in the anionic lipid-bound NMR structure of LL-37, has not been investigated. This study reports the structure and activity of SK-24. Interestingly, SK-24 is entirely helical (~100%) in phosphate buffer (PBS), more than LL-37 (84%), GI-20 (75%), and GF-17 (33%), while RI-10 and 17BIPHE2 are essentially randomly coiled (helix%: 7–10%). These results …