Laboratory Analysis Techniques for the Perinatal Microbiome: Implications for Studies of Probiotic Interventions.

The microbiome is composed of many organisms and is impacted by an intricate exchange between genetics and environmental factors. The perinatal microbiome influences both the developing fetus and the pregnant person. The purpose of this article is to describe the tests that are currently available for laboratory analysis of the perinatal microbiome in relationship to probiotic interventions. This article focuses on the bacterial component of the microbiome. Although adverse outcomes associated with the perinatal microbiome have been studied, a comprehensive understanding of the physiologic perinatal microbiome is still emerging. Early efforts to influence the perinatal microbiome through probiotics are currently under investigation. Unique terminology is defined, and the microbial composition of perinatal microbiota is summarized. The outcomes of studies of antenatal probiotics are summarized. Microbiome testing and analysis are defined and compared. Implications for perinatal care and probiotics research are presented.

Prevalence and molecular characterization of Staphylococcus aureus in commercially available meat over a one-year period in Iowa, USA.

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of infectious disease morbidity and mortality. Previous studies have confirmed the presence of S. aureus, including MRSA, on raw meat products. We investigated the prevalence and molecular epidemiology of S. aureus and MRSA in commercially-distributed antibiotic-free and conventional raw meat products (n = 3290) purchased in 8 Iowa retail stores weekly for a period of one year. Isolates were characterized using spa typing, and PCR was used to detect the presence of the Panton-Valentine leukocidin (PVL) and mecA genes. Quantitation of S. aureus on meat products was carried out one week per month. The prevalence of S. aureus on meat samples was 27.8% (913/3290). Compared to antibiotic-free meat samples, higher prevalence of both MRSA and methicillin-susceptible S. aureus (MSSA) were found in conventional meat samples. Among the S. aureus isolates, 18 were PVL-positive (1.9%) and 41 (4.5%) carried mecA. Phenotypic oxacillin resistance was observed for 17.1% (41/239) of the isolates tested, while 23% (55/239) were multi-drug resistant. A total of 132 spa types were detected from 913 contaminated meat samples. Overall, t002 was the most common spa type identified (137; 15.0%). The number of colony-forming units (CFU) per 10 g meat ranged from 2 to 517 (median: 8 CFU per 10 g of meat; mean: 28) with the highest bacterial load observed on turkey samples. These data reinforce the need to consider meat products as potential vehicles of S. aureus transmission from farm into human households, and the potential need for public health intervention programs pre and post-slaughter in meat processing facilities.

Swine Farming Is a Risk Factor for Infection With and High Prevalence of Carriage of Multidrug-Resistant Staphylococcus aureus.

BACKGROUND: Livestock-associated Staphylococcus aureus (LA-SA) has been documented worldwide. However, much remains unknown about LA-SA colonization and infection, especially in rural environments. METHODS: We conducted a large-scale prospective study of 1342 Iowans, including individuals with livestock contact and a community-based comparison group. Nasal and throat swabs were collected to determine colonization at enrollment, and skin infection swabs over 17 months were assessed for S. aureus. Outcomes included carriage of S. aureus, methicillin-resistant S. aureus (MRSA), tetracycline-resistant S. aureus (TRSA), multidrug-resistant S. aureus (MDRSA), and LA-SA. RESULTS: Of 1342 participants, 351 (26.2%; 95% confidence interval [CI], 23.8%-28.6%) carried S. aureus. MRSA was isolated from 34 (2.5%; 95% CI, 1.8%-3.5%) and LA-SA from 131 (9.8%; 95% CI, 8.3%-11.5%) of the 1342 participants. Individuals with current swine exposure were significantly more likely to carry S. aureus (prevalence ratio [PR], 1.8; 95% CI, 1.4-2.2), TRSA (PR, 8.4; 95% CI, 5.6-12.6), MDRSA (PR, 6.1; 95% CI, 3.8-10.0), and LA-SA (PR, 5.8; 95% CI, 3.9-8.4) than those lacking exposure. Skin infections (n = 103) were reported from 67 individuals, yielding an incidence rate of 6.6 (95% CI, 4.9-8.9) per 1000 person-months. CONCLUSIONS: Current swine workers are 6 times more likely to carry MDRSA than those without current swine exposure. We observed active infections caused by LA-SA. This finding suggests that individuals with livestock contact may have a high prevalence of exposure to, and potentially infection with, antibiotic-resistant S. aureus strains, including LA-SA strains.

Vaginal and Rectal microbiome changes following administration of a multi-species antenatal probiotic: A randomized control trial.

The gut and vaginal microbiome undergo changes during pregnancy which may be protective or harmful to the birthing person. Probiotics have been found to cause protective changes to the gut and vaginal microbiomes, with the potential to improve perinatal outcomes. This randomized control trial compares the vaginal and rectal microbiomes before and after an antenatal probiotic or placebo intervention, with a diverse group of pregnant people and a special focus on racial disparities. The vaginal and rectal microbiomes reveal non-significant increased Lactobacillus in the probiotics group, with a greater increase in participants who identified as Black. Potential implications and future study are discussed.

Antiviral potential of spirulina in individuals with human immunodeficiency virus or Hepatis C virus infections: A systematic review and meta-analysis.

BACKGROUND: Spirulina, a cyanobacterium or blue-green algae that contains phycocyanin, nutritional supplementation has been evaluated in patients living with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) due to its antiviral properties. This supplementation may be beneficial in low resource settings when awaiting antiretroviral therapy (ART) for HIV. This review aimed to evaluate the effectiveness of Spirulina supplement in antiviral-naïve HIV- and HCV-infected patients by assessing its immunological effect (Cluster of Differentiation 4 or CD-4 T-cell count) and disease progression (viral load). METHODS: We searched PubMed, Cochrane Library, Scopus, and Web of Science from inception through January 23, 2024. Two authors independently performed the study selection, data extraction, and risk of bias assessment. We pooled data by using a random-effects model and evaluated publication bias by a funnel plot. RESULTS: We identified 5552 articles, 5509 excluded at the title and abstract stage with 44 studies making it to the full text review. Of these 6 studies met the eligibility for inclusion in the final analysis as follows: 4 randomized controlled trials (RCTs) and 2 non-RCTs. The pooled results of the Spirulina intervention found significant improvements in biomarkers of clinical outcomes, viral load (VL) and CD4 T-cell (CD4) counts, in participants of the treatment group compared to controls; the VL had an overall Cohen's d effect size decrease of -2.49 (-4.80, -0.18) and CD4 had an overall effect size increase of 4.09 (0.75, 7.43). [Cohen's d benchmark: 0.2 = small effect; 0.5 = medium effect; 0.8 = large effect]. CONCLUSIONS: Findings from this systematic review showed a potential beneficial effect of Spirulina supplementation in HIV- and HCV-infected patients by increasing CD4 counts and decreasing viral load. However, further research in larger controlled clinical trials is needed to fully investigate the effect of this nutritional supplement on clinically relevant outcomes, opportunities for intervention, optimal dose, and cost-benefit of Spirulina supplementation.

Neighborhood socioeconomic status is associated with low diversity gut microbiomes and multi-drug resistant microorganism colonization.

Social disparities continue to limit universal access to health care, directly impacting both lifespan and quality of life. Concomitantly, the gut microbiome has been associated with downstream health outcomes including the global rise in antibiotic resistance. However, limited evidence exists examining socioeconomic status (SES) associations with gut microbiome composition. To address this, we collected information on the community-level SES, gut microbiota, and other individual cofactors including colonization by multidrug-resistant organisms (MDROs) in an adult cohort from Wisconsin, USA. We found an association between SES and microbial composition that is mediated by food insecurity. Additionally, we observed a higher prevalence of MDROs isolated from individuals with low diversity microbiomes and low neighborhood SES. Our integrated population-based study considers how the interplay of several social and economic factors combine to influence gut microbial composition while providing a framework for developing future interventions to help mitigate the SES health gap.

Quality improvement study on the effectiveness of intranasal povidone-iodine decolonization on surgery patients.

Background: Surgical site infection prevention and treatment remains a challenge in healthcare settings globally. The routine use of intranasal mupirocin for decolonization has challenges and preoperative intranasal povidone-iodine decolonization is another option. The purpose of this quality improvement study was to assess if a one-time preoperative intranasal povidone-iodine application could reduce the risk of the likelihood of nasal carriage of Staphylococcus aureus after surgery. Methods: Ambulatory Surgery Center patients were enrolled in an intranasal povidone-iodine decolonization quality improvement study as they reported at the pre-operative holding area. Pre-decolonization intranasal samples were collected, followed by intranasal application of povidone-iodine. Patients waited for a minimum of 20 minutes after application before proceeding with surgery. Nasal samples were again collected after surgery. Each sample was tested for S. aureus colonization using the 16S rRNA-mecA-nuc triplex polymerase chain reaction, standard biochemical tests, and qualitative culturing. Findings: In the 98 patients enrolled, 36% of these patients had intranasal colonization with S. aureus by 16S rRNA-mecA-nuc triplex polymerase chain reaction before surgery. Using a qualitative culture technique, 28% of patients tested positive for S. aureus before surgery and 20% of patients tested positive for S. aureus after surgery (P = 0.039). Conclusion: Intranasal preoperative povidone-iodine is an effective strategy in the decolonization of S. aureus from the nares if properly implemented.

A quality improvement study on the relationship between intranasal povidone-iodine and anesthesia and the nasal microbiota of surgery patients.

INTRODUCTION: The composition of the nasal microbiota in surgical patients in the context of general anesthesia and nasal povidone-iodine decolonization is unknown. The purpose of this quality improvement study was to determine: (i) if general anesthesia is associated with changes in the nasal microbiota of surgery patients and (ii) if preoperative intranasal povidone-iodine decolonization is associated with changes in the nasal microbiota of surgery patients. MATERIALS AND METHODS: One hundred and fifty-one ambulatory patients presenting for surgery were enrolled in a quality improvement study by convenience sampling. Pre- and post-surgery nasal samples were collected from patients in the no intranasal decolonization group (control group, n = 54). Pre-decolonization nasal samples were collected from the preoperative intranasal povidone-iodine decolonization group (povidone-iodine group, n = 97). Intranasal povidone-iodine was administered immediately prior to surgery and continued for 20 minutes before patients proceeded for surgery. Post-nasal samples were then collected. General anesthesia was administered to both groups. DNA from the samples was extracted for 16S rRNA sequencing on an Illumina MiSeq. RESULTS: In the control group, there was no evidence of change in bacterial diversity between pre- and post-surgery samples. In the povidone-iodine group, nasal bacterial diversity was greater in post-surgery, relative to pre-surgery (Shannon's Diversity Index (P = 0.038), Chao's richness estimate (P = 0.02) and Inverse Simpson index (P = 0.027). Among all the genera, only the relative abundance of the genus Staphylococcus trended towards a decrease in patients after application (FDR adjusted P = 0.06). Abundant genera common to both povidone-iodine and control groups included Staphylococcus, Bradyrhizobium, Corynebacterium, Dolosigranulum, Lactobacillus, and Moraxella. CONCLUSIONS: We found general anesthesia was not associated with changes in the nasal microbiota. Povidone-iodine treatment was associated with nasal microbial diversity and decreased abundance of Staphylococcus. Future studies should examine the nasal microbiota structure and function longitudinally in surgical patients receiving intranasal povidone-iodine.

Examining the association between the gastrointestinal microbiota and Gulf War illness: A prospective cohort study.

Gulf War Illness (GWI) affects 25-35% of the 1991 Gulf War Veteran (GWV) population. Patients with GWI experience pain, fatigue, cognitive impairments, gastrointestinal dysfunction, skin disorders, and respiratory issues. In longitudinal studies, many patients with GWI have shown little to no improvement in symptoms since diagnosis. The gut microbiome and diet play an important role in human health and disease, and preliminary studies suggest it may play a role in GWI. To examine the relationship between the gut microbiota, diet, and GWI, we conducted an eight-week prospective cohort study collecting stool samples, medications, health history, and dietary data. Sixty-nine participants were enrolled into the study, 36 of which met the case definition for GWI. The gut microbiota of participants, determined by 16S rRNA sequencing of stool samples, was stable over the duration of the study and showed no within person (alpha diversity) differences. Between group analyses (beta diversity) identified statistically significant different between those with and without GWI. Several taxonomic lineages were identified as differentially abundant between those with and without GWI (n = 9) including a greater abundance of Lachnospiraceae and Ruminococcaceae in those without GWI. Additionally, there were taxonomic differences between those with high and low healthy eating index (HEI) scores including a greater abundance of Ruminococcaceae in those with higher HEI scores. This longitudinal cohort study of GWVs found that participants with GWI had significantly different microbiomes from those without GWI. Further studies are needed to determine the role these differences may play in the development and treatment of GWI.

Incidence and Treatments of Bovine Mastitis and Other Diseases on 37 Dairy Farms in Wisconsin.

The aim of this research was to describe the incidence and treatments of mastitis and other common bovine diseases using one year of retrospective observational data (n = 50,329 cow-lactations) obtained from herd management software of 37 large dairy farms in Wisconsin. Incidence rate (IR) was defined as the number of first cases of each disease divided by the number of lactations per farm. Clinical mastitis (CM) remains the most diagnosed disease of dairy cows. Across all herds, the mean IR (cases per 100 cow-lactations) was 24.4 for clinical mastitis, 14.5 for foot disorders (FD), 11.2 for metritis (ME), 8.6 for ketosis (KE), 7.4 for retained fetal membranes (RFM), 4.5 for diarrhea (DI), 3.1 for displaced abomasum (DA), 2.9 for pneumonia (PN) and 1.9 for milk fever (MF). More than 30% of cows that had first cases of CM, DA, RFM, DI, and FD did not receive antibiotics. Of those treated, more than 50% of cows diagnosed with PN, ME and CM received ceftiofur as a treatment. The IR of mastitis and most other diseases was greater in older cows (parity ≥ 3) during the first 100 days of lactation and these cows were more likely to receive antibiotic treatments (as compared to younger cows diagnosed in later lactation). Cows of first and second parities in early lactation were more likely to remain in the herd after diagnosis of disease, as compared to older cows and cows in later stages of lactation. Most older cows diagnosed with CM in later lactation were culled before completion of the lactation. These results provide baseline data for disease incidence in dairy cows on modern U.S. dairy farms and reinforce the role of mastitis as an important cause of dairy cow morbidity.

Urinary lead level and colonization by antibiotic resistant bacteria: Evidence from a population-based study.

BACKGROUND: Infection by antibiotic resistant bacteria (ARB) is a global health crisis and asymptomatic colonization increases risk of infection. Nonhuman studies have linked heavy metal exposure to the selection of ARB; however, few epidemiologic studies have examined this relationship. This study analyzes the association between urinary lead level and colonization by ARB in a nonclinical human population. METHODS: Data came from the Survey of the Health of Wisconsin 2016-2017, and its ancillary Wisconsin Microbiome Study. Urinary lead levels, adjusted for creatinine, were used to assess exposure. ARB included methicillin resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), fluoroquinolone resistant Gram-negative bacilli (RGNB), and Clostridium difficile (C. diff), from skin, nose, and mouth swabs, and saliva and stool samples. Logistic regression, adjusted for covariates, was used to evaluate associations between Pb and ARB. Secondary analysis investigated Pb resistance from ARB isolates. RESULTS: Among 695 participants, 239 (34%) tested positive for ARB. Geometric mean urinary Pb (unadjusted) was 0.286 µg/L (95% confidence intervals [CI] = 0.263, 0.312) for ARB negative participants and 0.323 µg/L (95% CI = 0.287, 0.363) for ARB positive participants. Models adjusted for demographics, diet, and antibiotic use showed elevated odds of positive colonization for those in the 95th percentile (vs. below) of Pb exposure (odds ratio [OR] = 2.05, 95% CI = 0.95, 4.44), and associations were highest in urban residents (OR = 2.85, 95% CI = 1.07, 7.59). RGNB isolates were most resistant to Pb. DISCUSSION: These novel results suggest that Pb exposure is associated with increased colonization by ARB, and that RGNB are particularly resistant to Pb.

Wisconsin dairy farm worker perceptions and practices related to antibiotic use, resistance, and infection prevention using a systems engineering framework.

We studied farmworker practices and beliefs potentially contributing to transmission of bacteria and their associated antibiotic resistance genes (ARGs) among animals and farm workers to identify potential behavioral interventions to reduce the risk of bacterial transmission. Ten focus groups were conducted on eight Wisconsin dairy farms to assess potentially high-risk practices and farmworker knowledge and experiences with antibiotic use and resistance using the Systems Engineering in Patient Safety (SEIPS) framework. Farmworkers were asked to describe common on-farm tasks and the policies guiding these practices. We found workers demonstrated knowledge of the role of antibiotic stewardship in preventing the spread of ARGs. Worker knowledge of various forms of personal protective equipment was higher for workers who commonly reported glove-use. Additionally, workers knowledge regarding the importance of reducing ARG transmission varied but was higher than we had hypothesized. Programs to reduce ARG spread on dairy farms should focus on proper hand hygiene and personal protective equipment use at the level of knowledge, beliefs, and practices.

Nasal povidone-iodine implementation for preventing surgical site infections: Perspectives of surgical nurses.

INTRODUCTION: Preoperative nasal decolonization of surgical patients with nasal povidone-iodine (PI) has potential to eliminate pathogenic organisms responsible for surgical site infections. However, data on implementation of PI for quality improvement in clinical practice is limited. The purpose of this study was to evaluate the implementation feasibility, fidelity and acceptability of intranasal PI solution application by surgical nurses using the Integrated Promoting Action on Research Implementation in Health Services (i-PARIHS) conceptual framework. MATERIALS AND METHODS: Using the i-PARIHS framework to frame questions and guide interview content areas, we conducted 15 semi-structured interviews of pre- and post-operative care nurses in two facilities. We analyzed the data using deductive content analysis to evaluate nurses' experience and perceptions on preoperative intranasal PI solution decolonization implementation. Open coding was used to analyze the data to ensure all relevant information was captured. RESULTS: Each facility adopted a different quality improvement implementation strategy. The mode of facilitation, training, and educational materials provided to the nurses varied by facility. Barriers identified included lack of effective communication, insufficient information and lack of systematic implementation protocol. Action taken to mitigate some of the barriers included a collaboration between the study team and nurses to develop a systematic written protocol. The training assisted nurses to systematically follow the implementation protocol smoothly to ensure PI administration compliance, and to meet the goal of the facilities. Nurses' observations and feedback showed that PI did not cause any adverse effects on patients. CONCLUSIONS: We found that PI implementation was feasible and acceptable by nurses and could be extended to other facilities. However further studies are required to ensure standardization of PI application.

Household Pet Ownership and the Microbial Diversity of the Human Gut Microbiota.

The human gut microbiome has a great deal of interpersonal variation due to both endogenous and exogenous factors, like household pet exposure. To examine the relationship between having a pet in the home and the composition and diversity of the adult gut microbiome, we conducted a case-control study nested in a larger, statewide study, the Survey of the Health of Wisconsin. Stool samples were collected from 332 participants from unique households and analyzed using 16S rRNA sequencing on the Illumina MiSeq. One hundred and seventy-eight participants had some type of pet in the home with dogs and cats being the most prevalent. We observed no difference in alpha and beta diversity between those with and without pets, though seven OTUs were significantly more abundant in those without pets compared to those with pets, and four were significantly more abundant in those with pets. When stratifying by age, seven of these remained significant. These results suggest that pet ownership is associated with differences in the human gut microbiota. Further research is needed to better characterize the effect of pet ownership on the human gut microbiome.

Fecal microbiota transplantation for patients on antibiotic treatment with C. difficile infection history (GRAFT): Study protocol for a phase II, randomized, double-blind, placebo-controlled trial to prevent recurrent C. difficile infections.

Recurrent Clostridiodes difficile infections (rCDIs) are a burdensome problem. Patients with a history of CDI that are prescribed antibiotics are at a high risk for recurrence. Fecal microbiota transplantation (FMT) has been shown to be an effective treatment for rCDI, though there is little information on the impact of FMT with antibiotics on the gut microbiome. We are conducting a clinical trial of FMT to prevent rCDI in patients with a history of CDI currently taking antibiotics. Our primary objective is to determine the effect of FMT on the gut microbiome during antibiotic exposure. Our secondary aim is to assess safety and feasibility of using FMT as a prophylaxis for CDI. We plan to enroll 30 patients into a phase II randomized, double-blind, placebo-controlled trial with three arms: (1) 5 FMT capsules per day during antibiotic treatment and for 7 days post antibiotic cessation, (2) a one-time dose of 30 FMT capsules 48-72 h post cessation of antibiotic treatment, or (3) 5 placebo capsules per day during antibiotic treatment and for 7 days post antibiotic treatment. Patients provide stool samples throughout the duration of the study and are cultured C. difficile. Sequencing of the V4 region of the 16S rRNA gene will be carried out to assess the gut microbiota. Results of this study will provide information on the impact of FMT on the gut microbiome as well as the necessary data to examine whether or not prophylactic FMT should be explored further as a way to prevent CDI recurrence.

Use of a systems engineering framework to assess perceptions and practices about antimicrobial resistance of workers on large dairy farms in Wisconsin.

We studied farmworker practices potentially contributing to transmission of bacteria and antimicrobial resistant genes (ARGs) among animals and farm workers to identify human behavioral interventions to reduce exposure risk. Ten focus groups were conducted on eight farms to explore potentially high-risk practices and farmworker knowledge and experiences with antimicrobial use and resistance using the Systems Engineering in Patient Safety (SEIPS) framework. Farmworkers were asked to describe common tasks and the policies guiding these practices. We found workers demonstrated knowledge of the role of antibiotic stewardship in preventing the spread of ARGs. Knowledge of various forms of personal protective equipment was higher for workers who commonly reported glove-use. Knowledge regarding the importance of reducing ARG transmission varied but was greater than previously reported. Programs to reduce ARG spread on dairy farms should focus on proper hand hygiene and personal protective equipment use but at the level of knowledge, beliefs, and practices.

Use of face coverings in public during the COVID-19 pandemic: an observational study.

Public health agencies have recommended that the public wear face coverings, including face masks, to mitigate COVID-19 transmission. However, the extent to which the public has adopted this recommendation is unknown. An observational study of 3,271 members of the public in May and June 2020 examined face covering use at grocery stores across Wisconsin. We found that only 41.2% used face coverings. Individuals who appeared to be female or older adults had higher odds of using face coverings. Additionally, location-specific variables such as expensiveness of store, county-level population and county-level COVID-19 case prevalence were associated with increased odds of using face coverings. To our knowledge, this is the first direct observational study examining face covering behavior by the public in the U.S., and our findings have implications for public health agencies during the COVID-19 pandemic.

The nasal and oropharyngeal microbiomes of healthy livestock workers.

Little information exists on the microbiomes of livestock workers. A cross-sectional, epidemiological study was conducted enrolling 59 participants (26 of which had livestock contact) in Iowa. Participants were enrolled in one of four ways: from an existing prospective cohort study (n = 38), from the Iowa Department of Natural Resources Animal Feeding Operations database (n = 17), through Iowa county fairs (n = 3), and through snowball sampling (n = 1). We collected swabs from the nares and oropharynx of each participant to assess the microbiome via 16s rRNA sequencing. We observed livestock workers to have greater diversity in their microbiomes compared to those with no livestock contact. In the nares, there were 27 operational taxonomic units found to be different between livestock workers and non-livestock workers with the greatest difference seen with Streptococcus and Proteobacteria. In the oropharynx, livestock workers with swine exposure were more likely to carry several pathogenic organisms. The results of this study are the first to characterize the livestock worker nasal and oropharyngeal microbiomes.

The impact of chlorhexidine gluconate on the skin microbiota of children and adults: A pilot study.

We examined the effect of chlorhexidine gluconate (CHG) bathing on the skin microbiota of adult and pediatric patients. We observed no differences in pediatric patients; however, multiple genera of bacteria were observed to be significantly less abundant in the adults bathing with CHG. Further research is needed to determine the long-term impact of CHG use on the skin microbiota.

Urinary lead concentration and composition of the adult gut microbiota in a cross-sectional population-based sample.

BACKGROUND: Lead (Pb) is a ubiquitous environmental contaminant with an array of detrimental health effects in children and adults, including neurological and immune dysfunction. Emerging evidence suggests that Pb exposure may alter the composition of the gut microbiota, however few studies have examined this association in human populations. The purpose of this study was to examine the association between urinary Pb concentration and the composition of the adult gut microbiota in a population-based sample of adults. METHODS: Data used in this study were collected as part of the Survey of the Health of Wisconsin (SHOW) and its ancillary microbiome study. The SHOW is a household-based health examination survey of Wisconsin residents, collecting a variety of survey data on health determinants and outcomes, as well as objective measurements of body habitus, and biological specimens including urine. The ancillary microbiome study added additional questions and biological specimen collection, including stool, from participants age 18+. Pb concentration was analyzed in urine samples, and gut microbiota composition was assessed using DNA sequencing of the 16S rRNA V4 region, extracted from stool samples. Data processing and statistical analyses were performed in mothur, Python, R, and SAS. RESULTS: Of 696 participants, urinary Pb concentration was highest in those age 70+, females, those with a high school diploma or lower, current and former smokers, and those without indoor pets. In adjusted models, increasing urinary Pb levels were associated with increases in microbial α-diversity (p = 0.071) and richness (p = 0.005). Differences in microbial ß-diversity were significantly associated (p = 0.003) with differences in urinary Pb level. Presence of Proteobacteria, including members of the Burkholderiales, was significantly associated with increased urinary Pb. CONCLUSION: These results suggest that Pb exposure is associated with differences in the composition of the adult gut microbiota in a population-based human sample. Further investigation of this association is warranted.