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Browsing by Author "Muzny, Christina A."
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Item A novel Gardnerella, Prevotella, and Lactobacillus standard that improves accuracy in quantifying bacterial burden in vaginal microbial communities(Frontiers Media, 2023-06-19) Elnaggar, Jacob H.; Ardizzone, Caleb M.; Cerca, Nuno; Toh, Evelyn; Łaniewski, Paweł; Lillis, Rebecca A.; Herbst-Kralovetz, Melissa M.; Quayle, Alison J.; Muzny, Christina A.; Taylor, Christopher M.; Microbiology and Immunology, School of MedicineBacterial vaginosis (BV) is the most common vaginal dysbiosis. In this condition, a polymicrobial biofilm develops on vaginal epithelial cells. Accurately quantifying the bacterial burden of the BV biofilm is necessary to further our understanding of BV pathogenesis. Historically, the standard for calculating total bacterial burden of the BV biofilm has been based on quantifying Escherichia coli 16S rRNA gene copy number. However, E. coli is improper for measuring the bacterial burden of this unique micro-environment. Here, we propose a novel qPCR standard to quantify bacterial burden in vaginal microbial communities, from an optimal state to a mature BV biofilm. These standards consist of different combinations of vaginal bacteria including three common BV-associated bacteria (BVAB) Gardnerella spp. (G), Prevotella spp. (P), and Fannyhessea spp. (F) and commensal Lactobacillus spp. (L) using the 16S rRNA gene (G:P:F:L, G:P:F, G:P:L and 1G:9L). We compared these standards to the traditional E. coli (E) reference standard using known quantities of mock vaginal communities and 16 vaginal samples from women. The E standard significantly underestimated the copy numbers of the mock communities, and this underestimation was significantly greater at lower copy numbers of these communities. The G:P:L standard was the most accurate across all mock communities and when compared to other mixed vaginal standards. Mixed vaginal standards were further validated with vaginal samples. This new G:P:L standard can be used in BV pathogenesis research to enhance reproducibility and reliability in quantitative measurements of BVAB, spanning from the optimal to non-optimal (including BV) vaginal microbiota.Item Impact of testosterone use on the vaginal microbiota of transgender men, including susceptibility to bacterial vaginosis: study protocol for a prospective, observational study(BMJ, 2023-03-27) Muzny, Christina A.; Van Gerwen, Olivia T.; Schroeder, Julia A.; Kay-Duncan, Emma Sophia; Siwakoti, Krishmita; Aaron, Kristal J.; Eastlund, Isaac C.; Graves, Keonte J.; Elnaggar, Jacob H.; Tamhane, Ashutosh; Long, Dustin; Van Wagoner, Nicholas; Toh, Evelyn; Taylor, Christopher M.; Medicine, School of MedicineIntroduction: The effect of testosterone (T) therapy on the vaginal microbiota of transgender men (TGM) is not well characterised, although one cross-sectional study comparing the vaginal microbiota of cisgender women to TGM on T≥1 year found that, in 71% of the TGM, the vaginal microbiota was less likely to be Lactobacillus-dominated and more likely to be enriched with >30 other bacterial species, many associated with bacterial vaginosis (BV). This prospective study aims to investigate changes in the composition of the vaginal microbiota over time in TGM who retain their natal genitalia (ie, vagina) and initiate T. In addition, we will identify changes in the vaginal microbiota preceding incident BV (iBV) in this cohort while investigating behavioural factors, along with hormonal shifts, which may be associated with iBV. Methods and analysis: T-naïve TGM who have not undergone gender-affirming genital surgery with normal baseline vaginal microbiota (ie, no Amsel criteria, normal Nugent Score with no Gardnerella vaginalis morphotypes) will self-collect daily vaginal specimens for 7 days prior to initiating T and for 90 days thereafter. These specimens will be used for vaginal Gram stain, 16S rRNA gene sequencing and shotgun metagenomic sequencing to characterise shifts in the vaginal microbiota over time, including development of iBV. Participants will complete daily diaries on douching, menses and behavioural factors including sexual activity during the study. Ethics and dissemination: This protocol is approved through the single Institutional Review Board mechanism by the University of Alabama at Birmingham. External relying sites are the Louisiana State University Health Sciences Center, New Orleans Human Research Protection Program and the Indiana University Human Research Protection Program. Study findings will be presented at scientific conferences and peer-reviewed journals as well as shared with community advisory boards at participating gender health clinics and community-based organisations servicing transgender people.Item Sexual behavior shapes male genitourinary microbiome composition(Elsevier, 2023) Toh, Evelyn; Xing, Yue; Gao, Xiang; Jordan, Stephen J.; Batteiger, Teresa A.; Batteiger, Byron E.; Van Der Pol, Barbara; Muzny, Christina A.; Gebregziabher, Netsanet; Williams, James A.; Fortenberry, Lora J.; Fortenberry, J. Dennis; Dong, Qunfeng; Nelson, David E.; Microbiology and Immunology, School of MedicineThe origin, composition, and significance of the distal male urethral microbiome are unclear, but vaginal microbiome dysbiosis is linked to new sex partners and several urogynecological syndromes. We characterized 110 urethral specimens from men without urethral symptoms, infections, or inflammation using shotgun metagenomics. Most urethral specimens contain characteristic lactic acid bacteria and Corynebacterium spp. In contrast, several bacteria associated with vaginal dysbiosis were present only in specimens from men who reported vaginal intercourse. Sexual behavior, but not other evaluated behavioral, demographic, or clinical variables, strongly associated with inter-specimen variance in urethral microbiome composition. Thus, the male urethra supports a simple core microbiome that is established independent of sexual exposures but can be re-shaped by vaginal sex. Overall, the results suggest that urogenital microbiology and sexual behavior are inexorably intertwined, and show that the male urethra harbors female urogenital pathobionts.