Browsing by Author "Bauer, Margaret"

Now showing 1 - 4 of 4
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    Exploring the Bacterial Diversity of the Male Urethra During Idiopathic Urethritis
    (2020-08) Farrell, Rowan Micah; Nelson, David E.; Bauer, Margaret; Spinola, Stanley
    Idiopathic urethritis (IU) comprises up to 50% of symptomatic cases of male urethritis in clinical settings. The syndrome is of an unknown etiology but may be due to an as yet unidentified bacterial pathogen(s). We were interested in identifying pathogens that could cause IU using multiple methods. Shotgun metagenomic sequencing or 16S rRNA sequencing methods can provide rich datasets but are limited by the completeness of the corresponding sequence reference databases. We generated metagenomic and 16S datasets from DNA extracted from urethral swabs of men with IU to determine the composition of their urethral microbiome. In order to enrich the corresponding reference databases used to identify the reads in the sequence datasets, I cultivated bacteria from the first void urine (FVU) of men with IU. My goal was to grow and whole genome sequence bacterial isolates that are not currently represented in the reference databases. Of the 216 men we enrolled at the Bell Flower STD clinic in Indianapolis, IN, 59 men had IU. I grew a total of 802 isolates from the FVU of the IU patients and identified those isolates using colony-based 16S rRNA PCR. Based on % sequence similarity to the nearest type strain, I sorted the 16S alleles into four categories: Species (≥98 % identity) (N=264), Genus (≥95 % identity) (N=407), Closest Match (<95 % identity) (N=95), and No Hit (0 % identity) (N=22). There were 24 genera represented in the isolate collection. Of these, the six most abundant genera were Streptococcus, Staphylococcus, Corynebacterium, Haemophilus, Gardnerella, and Prevotella. These six genera composed nearly 80% of all IU-associated isolates. All sequences below 98% sequence similarity represent potentially novel strains of bacteria. We will proceed with whole genome sequencing of bacterial isolates with the goal of improving genome database coverage of bacterial diversity in the male urethra.
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    Inflammation by Toxoplasma gondii Infection Induces Prostatic Hyperplasia and Accompanying Urinary Dysfunction
    (2024-08) Stanczak, Emily F.; Arrizabalaga, Gustavo; Bauer, Margaret; Jerde, Travis; Nakshatri, Harikrishna
    Benign prostatic hyperplasia is the non-cancerous enlargement of the prostate. This syndrome develops as men age and affects 50% of men by the age of 50 and 80% of men by the age of 80. BPH is associated with a pattern of symptoms and pathology in patients that can be painful, problematic, and lower the quality of life. BPH is a multifactorial disease which may develop due to lifestyle choices, genetics, metabolic disorder, and potentially infection of the organ. Interestingly, previous work from our research group showed that the common parasite T. gondii can infect and establish a chronic infection in the prostate of mice resulting in histological hyperplasia and glandular nodule formation, reminiscent of that observed in men with BPH. This leads to the hypothesis that T. gondii contributes to BPH in humans. In this work, we investigated whether there is a correlation between T. gondii infection and BPH using a cohort of age matched BPH diagnosed and non-BPH diagnosed control donors. My data show that men diagnosed with BPH are significantly more likely to have evidence of T. gondii infection than undiagnosed controls. Additionally, men with antibodies against T. gondii and BPH had significantly more severe pathology in several categories including and most notably in epithelial and glandular nodules seen only in a steroid hormone model of the disease. Moreover, I have determined that mice infected with parasites demonstrated abnormal urination pattern behavior indicating lower urinary tract dysfunction. Based on these results, we conclude that T. gondii can contribute to the development and severity of BPH and BPH pathology in humans. In addition, T. gondii can potentially be used as a model for BPH and BPH-like symptoms and pathology in mice and other model organisms.
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    The Role of Chlamydia Protein TC0600 in Gastrointestinal Tract Infection
    (2021-12) Alrebdi, Waleed; Nelson, David; Bauer, Margaret; Yang, X. Frank
    Chlamydia is the most frequently reported bacterial sexually transmitted infection in the world. Most urogenital chlamydia infections in men and women are asymptomatic, but these infections can lead to irreparable damage in the reproductive system and other tissues. Apart from the urogenital chlamydial infections, we know that chlamydia infects the gastrointestinal tract (GIT) in humans and can colonize the GIT for extended intervals without eliciting pathology. We are interested in investigating tissue tropism determinants in Chlamydia spp. because these could be targeted to development live-attenuated vaccines. Recently, we generated mutagenized isolates of the mouse pathogen Chlamydia muridarum, a close relative of the human pathogen Chlamydia trachomatis which causes chlamydia. One mutant that we isolated is significantly attenuated in murine gastrointestinal tissues compared to wild type, but retains its pathogenicity in the murine urogenital tract. Using novel genetic techniques, whole-genome sequencing, and complementation using newly developed vector systems we identified a chromosomal factor, tc0600, that we believe mediates the altered tissue tropism phenotype of this mutant in mice. Notably, the Chlamydia trachomatis ortholog of tc0600 has been linked to chlamydial GIT tropism in humans.
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    The Role of PfEMP1 Expression and Immunity in Ugandian Children with Severe Malaria
    (2022-05) Fernander, Elizabeth M.; John, Chandy; Bauer, Margaret; Gilk, Stacey; Tran, Tuan
    Severe malaria, primarily caused by Plasmodium falciparum infection, is among the leading causes of childhood mortality globally. A key virulence factor and source of antigenic variation and immune evasion during infection is P. falciparum erythrocyte membrane protein 1 (PfEMP1). Encoded for by approximately 60 var genes, this complex protein mediates cytoadherence of infected erythrocytes to the host endothelium and is a prominent immune target for the anti-malarial immune response in children. During severe malaria, specific domains of PfEMP1 that bind to endothelial protein C receptor (EPCR) and intercellular adhesion molecule-1 (ICAM-1) on host endothelial cells, are more prevalently expressed. The interaction of these proteins and infected erythrocytes mediates the sequestration of infected erythrocytes and plays a role in severe malaria pathogenesis. Antibodies to these domains develop over time with exposure to the parasite and are thought to contribute to immunity against severe malaria in children. In this study, whole blood samples from children with different forms of severe malaria, enrolled in two observational prospective cohort studies were used to quantify the expression of PfEMP1 domains using RT-qPCR and to measure the antibody response to PfEMP1 domains via a bead-based multiplex immunoassay. Using these samples, we demonstrated that although the expression of var transcripts encoding PfEMP1 domains was generally similar across children with different forms of severe malaria, the expression of variants encoding specific EPCR-binding domains was associated with thrombocytopenia and severe anemia. The antibody response to PfEMP1 domains in children with severe malaria was highest in children with SMA and children with asymptomatic parasitemia, but not associated with decreased risk of additional malaria episodes. Overall, the results of this study suggest that PfEMP1 is acting similarly across different forms of severe malaria but that it can be related to pathogenesis and severe malaria immunity.