Publications by authors named "David Fredricks"

Background: The etiology of nongonococcal urethritis (NGU) is incompletely understood. We sought to determine if genitourinary bacterial diversity or specific taxa were associated with incident NGU.

Methods: From August 2014-July 2018, men who have sex with women attending a sexual health clinic were clinically evaluated, including Mycoplasma genitalium (MG) and Chlamydia trachomatis (CT) testing, at enrollment and six monthly visits.

View Article and Find Full Text PDF
Article Synopsis
  • A study examined the effects of metronidazole, an antibiotic, on bacterial vaginosis (BV)-associated bacteria, which are linked to a higher risk of acquiring HIV.
  • Vaginal samples from 22 individuals were taken daily after a BV diagnosis, revealing that metronidazole significantly reduced the concentration of various bacteria over a treatment period of 5-7 days.
  • The results indicated that, while most bacterial levels decreased substantially, some bacteria took longer to be cleared, suggesting that metronidazole could be an effective method to reduce potential HIV infection risk linked to these bacteria.
View Article and Find Full Text PDF

Summary: Identification of balances of bacterial taxa in relation to continuous and dichotomous outcomes is an increasingly frequent analytic objective in microbiome profiling experiments. SurvBal enables the selection of balances in relation to censored survival or time-to-event outcomes which are of considerable interest in many biomedical studies. The most commonly used survival models-the Cox proportional hazards and parametric survival models are included in the package, which are used in combination with step-wise selection procedures to identify the optimal associated balance of microbiome, i.

View Article and Find Full Text PDF

Background: Few investigations have assessed contributions of both vaginal bacteria and proinflammatory immune mediators to human immunodeficiency virus (HIV) acquisition risk in a prospective cohort.

Methods: We conducted a nested case-control study of African women who participated in a randomized placebo-controlled trial of daily oral versus vaginal tenofovir-based preexposure prophylaxis for HIV infection. Vaginal concentrations of 23 bacterial taxa and 16 immune mediators were measured.

View Article and Find Full Text PDF

Background: Bacterial vaginosis (BV) is a condition marked by high vaginal bacterial diversity. Gardnerella vaginalis has been implicated in BV but is also detected in healthy women. The Gardnerella genus has been expanded to encompass 6 validly named species and several genomospecies.

View Article and Find Full Text PDF

Background: Studies evaluating the association between the vaginal microbiota and miscarriage have produced variable results.

Objective: This study evaluated the association between periconceptual and first-trimester vaginal microbiota and women's risk for miscarriage.

Methods: At monthly preconception visits and at 9-12 weeks gestation, women collected vaginal swabs for molecular characterisation of the vaginal microbiota.

View Article and Find Full Text PDF

Objective: In premenopausal individuals, vaginal microbiota diversity and lack of Lactobacillus dominance are associated with greater mucosal inflammation, which is linked to a higher risk of cervical dysplasia and infections. It is not known if the association between the vaginal microbiota and inflammation is present after menopause, when the vaginal microbiota is generally higher-diversity and fewer people have Lactobacillus dominance.

Methods: This is a post hoc analysis of a subset of postmenopausal individuals enrolled in a randomized trial for treatment of moderate-severe vulvovaginal discomfort that compared vaginal moisturizer, estradiol, or placebo.

View Article and Find Full Text PDF

Several bacterial vaginosis (BV)-associated bacteria have been associated with elevated risk of HIV acquisition, however susceptibility of these bacteria to antibiotics is poorly understood. Vaginal samples were collected from 22 persons daily for two weeks following BV diagnosis. Metronidazole treatment was prescribed for 5-7 days.

View Article and Find Full Text PDF

Investigating the human fallopian tube (FT) microbiota has significant implications for understanding the pathogenesis of ovarian cancer (OC). In this large prospective study, we collected swabs intraoperatively from the FT and other surgical sites as controls to profile the microbiota in the FT and to assess its relationship with OC. Eighty-one OC and 106 non-cancer patients were enrolled and 1001 swabs were processed for 16S rRNA gene PCR and sequencing.

View Article and Find Full Text PDF

Immunoglobulin (Ig) bacterial coating has been described in the gastrointestinal tract and linked to inflammatory bowel disease; however, little is known about Ig coating of vaginal bacteria and whether it plays a role in vaginal health including bacterial vaginosis (BV). We examined Ig coating in 18 women with symptomatic BV followed longitudinally before, 1 week, and 1 month after oral metronidazole treatment. Immunoglobulin A (IgA) and/or immunoglobulin G (IgG) coating of vaginal bacteria was assessed by flow cytometry, and Ig coated and uncoated bacteria were sorted and characterized using 16S rRNA sequencing.

View Article and Find Full Text PDF

Four obligately anaerobic Gram-positive bacteria representing one novel genus and two novel species were isolated from the female genital tract. Both novel species, designated UPII 610-J and KA00274, and an additional isolate of each species were characterized utilizing biochemical, genotypic and phylogenetic analyses. All strains were non-motile and non-spore forming, asaccharolytic, non-cellulolytic and indole-negative coccobacilli.

View Article and Find Full Text PDF

To facilitate in vitro mechanistic studies in pelvic inflammatory disease and subsequent tubal factor infertility, we sought to establish patient tissue derived fallopian tube (FT) organoids and to study their inflammatory response to acute vaginal bacterial infection. FT tissues were obtained from four patients after salpingectomy for benign gynecological diseases. We introduced acute infection in the FT organoid culture system by inoculating the organoid culture media with two common vaginal bacterial species, Lactobacillus crispatus and Fannyhessea vaginae.

View Article and Find Full Text PDF

Acute graft-versus-host disease (aGVHD) remains a major limitation of allogeneic stem cell transplantation (SCT), and severe intestinal manifestation is the major cause of early mortality. Intestinal microbiota control MHC class II (MHC-II) expression by ileal intestinal epithelial cells (IECs) that promote GVHD. Here, we demonstrated that genetically identical mice of differing vendor origins had markedly different intestinal microbiota and ileal MHC-II expression, resulting in discordant GVHD severity.

View Article and Find Full Text PDF

Investigating the human fallopian tube (FT) microbiota has significant implications for understanding the pathogenesis of ovarian cancer (OC). In this large prospective study, we collected swabs intraoperatively from the FT and other surgical sites as controls to profile the microbiota in the FT and to assess its relationship with OC. 81 OC and 106 non-cancer patients were enrolled and 1001 swabs were processed for 16S rRNA gene PCR and sequencing.

View Article and Find Full Text PDF

Metaproteomics, a method for untargeted, high-throughput identification of proteins in complex samples, provides functional information about microbial communities and can tie functions to specific taxa. Metaproteomics often generates less data than other omics techniques, but analytical workflows can be improved to increase usable data in metaproteomic outputs. Identification of peptides in the metaproteomic analysis is performed by comparing mass spectra of sample peptides to a reference database of protein sequences.

View Article and Find Full Text PDF

To facilitate mechanistic studies in pelvic inflammatory disease (PID) and subsequent tubal factor infertility, as well as ovarian carcinogenesis, we sought to establish patient tissue derived fallopian tube (FT) organoids and to study their inflammatory response to acute vaginal bacterial infection. Experimental study. Academic medical and researchcenter.

View Article and Find Full Text PDF

Importance: Certain antibiotic exposures have been associated with increased rates of acute graft-vs-host disease (aGVHD) after allogeneic hematopoietic cell transplantation (allo-HCT). Since antibiotic exposure can both affect and be affected by infections, analyzing time-dependent exposure in the presence of multiple potential confounders, including prior antibiotic exposures, poses specific analytical challenges, necessitating both a large sample size and unique approaches.

Objective: To identify antibiotics and antibiotic exposure timeframes associated with subsequent aGVHD.

View Article and Find Full Text PDF

Background: Women's increased risk of HIV acquisition during pregnancy and postpartum may be mediated by changes in vaginal microbiota and/or cytokines.

Methods: A cohort of 80 Kenyan women who were HIV-1 seronegative contributed 409 vaginal samples at 6 pregnancy time points: periconception, positive pregnancy test result, first trimester, second trimester, third trimester, and postpartum. Concentrations of vaginal bacteria linked with HIV risk and Lactobacillus spp were measured using quantitative polymerase chain reaction.

View Article and Find Full Text PDF

Background: In women, genital herpes simplex virus type 2 (HSV-2) infection is associated with increased risk for recurrent bacterial vaginosis (BV), but causal relationships are unclear.

Methods: Women with a self-reported history of BV and HSV-2 seropositivity self-collected vaginal and anogenital swabs for 2 nonconsecutive 28-day periods, in the absence or presence of valacyclovir suppressive therapy (500 mg daily). HSV polymerase chain reaction was performed on anogenital swabs; vaginal swabs were used for assessment of BV by Nugent score and quantification of vaginal microbiota.

View Article and Find Full Text PDF

Background: The association between vaginal washing and HIV risk may be mediated by vaginal washing-associated changes in vaginal microbiota.

Methods: Data from a cohort of HIV-negative US and Kenyan women enrolled in the Preventing Vaginal Infections trial were analyzed. Vaginal fluid samples and vaginal washing data were collected every 2 months for 12 months.

View Article and Find Full Text PDF

Objective: To facilitate mechanistic studies in pelvic inflammatory disease (PID) and subsequent tubal factor infertility, as well as ovarian carcinogenesis, we sought to establish patient tissue derived fallopian tube (FT) organoids and to study their inflammatory response to acute vaginal bacterial infection.

Design: Experimental study.

Setting: Academic medical and research center.

View Article and Find Full Text PDF

Background: There is an unmet need for a clinical diagnostic technology to detect bacterial vaginosis (BV) rapidly and accurately. Novel point-of-care (POC) tests have the potential to fulfill this gap. Our objective was to determine the cost-effectiveness of a hypothetical clinician-administered POC test for diagnosing BV in the United States.

View Article and Find Full Text PDF

Objectives: Bacterial vaginosis-associated bacterium 2 (BVAB2), and spp are highly predictive of bacterial vaginosis (BV) in cisgender women. They have been associated with non-gonococcal urethritis (NGU) in cisgender men in some but not all populations. We evaluated this association in a cross-sectional study of cisgender men who have sex with women only (MSW).

View Article and Find Full Text PDF