Frequency-dependent selection can forecast evolution in Streptococcus pneumoniae.

Predicting how pathogen populations will change over time is challenging. Such has been the case with Streptococcus pneumoniae, an important human pathogen, and the pneumococcal conjugate vaccines (PCVs), which target only a fraction of the strains in the population. Here, we use the frequencies of accessory genes to predict changes in the pneumococcal population after vaccination, hypothesizing that these frequencies reflect negative frequency-dependent selection (NFDS) on the gene products. We find that the standardized predicted fitness of a strain, estimated by an NFDS-based model at the time the vaccine is introduced, enables us to predict whether the strain increases or decreases in prevalence following vaccination. Further, we are able to forecast the equilibrium post-vaccine population composition and assess the invasion capacity of emerging lineages. Overall, we provide a method for predicting the impact of an intervention on pneumococcal populations with potential application to other bacterial pathogens in which NFDS is a driving force.

Characterization of Blighia sapida seed extracts.

Blighia sapida, commonly known as the ackee, is a member of the Sapindaceae family. The tree is native to the forests of West Africa and was brought to the Caribbean and later Florida, where it is cultivated as an orchard crop in some areas. Arilli of the fruit are processed to make canned ackee in brine whereas the seeds, raphe and pods are discarded. Physiochemical studies were conducted on extracts of the seed. Qualitative analysis detected the presence of phenolics and reducing sugars. Aqueous extracts of the seeds (ASE) exhibited free radical scavenging activity and had an inhibitory concentration of 2.59 mg/mL. Gas chromatography mass spectrometry led to the identification of several metabolites including amino acids and fatty acids. Hypoglycin B was isolated utilizing ion exchange chromatography. Fourier transform infrared spectroscopy of hypoglycin B detected a band resonating at 3070 cm-1 which may be attributed to the methylenecyclopropane moiety of hypoglycin B. The seeds had a lipid content of 5.72 ± 0.25 % (w/w). The ackee seed oil (ASO) had a saponification value of 152.07 ± 37 and a carotenoid content of 23.7 ± 1.8 mg/kg. The ackee seeds are a source of bioactive components.

The impact of serotype-specific vaccination on phylodynamic parameters of Streptococcus pneumoniae and the pneumococcal pan-genome.

In the United States, the introduction of the heptavalent pneumococcal conjugate vaccine (PCV) largely eliminated vaccine serotypes (VT); non-vaccine serotypes (NVT) subsequently increased in carriage and disease. Vaccination also disrupts the composition of the pneumococcal pangenome, which includes mobile genetic elements and polymorphic non-capsular antigens important for virulence, transmission, and pneumococcal ecology. Antigenic proteins are of interest for future vaccines; yet, little is known about how the they are affected by PCV use. To investigate the evolutionary impact of vaccination, we assessed recombination, evolution, and pathogen demographic history of 937 pneumococci collected from 1998-2012 among Navajo and White Mountain Apache Native American communities. We analyzed changes in the pneumococcal pangenome, focusing on metabolic loci and 19 polymorphic protein antigens. We found the impact of PCV on the pneumococcal population could be observed in reduced diversity, a smaller pangenome, and changing frequencies of accessory clusters of orthologous groups (COGs). Post-PCV7, diversity rebounded through clonal expansion of NVT lineages and inferred in-migration of two previously unobserved lineages. Accessory COGs frequencies trended toward pre-PCV7 values with increasing time since vaccine introduction. Contemporary frequencies of protein antigen variants are better predicted by pre-PCV7 values (1998-2000) than the preceding period (2006-2008), suggesting balancing selection may have acted in maintaining variant frequencies in this population. Overall, we present the largest genomic analysis of pneumococcal carriage in the United States to date, which includes a snapshot of a true vaccine-naïve community prior to the introduction of PCV7. These data improve our understanding of pneumococcal evolution and emphasize the need to consider pangenome composition when inferring the impact of vaccination and developing future protein-based pneumococcal vaccines.

Global emergence and population dynamics of divergent serotype 3 CC180 pneumococci.

Streptococcus pneumoniae serotype 3 remains a significant cause of morbidity and mortality worldwide, despite inclusion in the 13-valent pneumococcal conjugate vaccine (PCV13). Serotype 3 increased in carriage since the implementation of PCV13 in the USA, while invasive disease rates remain unchanged. We investigated the persistence of serotype 3 in carriage and disease, through genomic analyses of a global sample of 301 serotype 3 isolates of the Netherlands3-31 (PMEN31) clone CC180, combined with associated patient data and PCV utilization among countries of isolate collection. We assessed phenotypic variation between dominant clades in capsule charge (zeta potential), capsular polysaccharide shedding, and susceptibility to opsonophagocytic killing, which have previously been associated with carriage duration, invasiveness, and vaccine escape. We identified a recent shift in the CC180 population attributed to a lineage termed Clade II, which was estimated by Bayesian coalescent analysis to have first appeared in 1968 [95% HPD: 1939-1989] and increased in prevalence and effective population size thereafter. Clade II isolates are divergent from the pre-PCV13 serotype 3 population in non-capsular antigenic composition, competence, and antibiotic susceptibility, the last of which resulting from the acquisition of a Tn916-like conjugative transposon. Differences in recombination rates among clades correlated with variations in the ATP-binding subunit of Clp protease, as well as amino acid substitutions in the comCDE operon. Opsonophagocytic killing assays elucidated the low observed efficacy of PCV13 against serotype 3. Variation in PCV13 use among sampled countries was not independently correlated with the CC180 population shift; therefore, genotypic and phenotypic differences in protein antigens and, in particular, antibiotic resistance may have contributed to the increase of Clade II. Our analysis emphasizes the need for routine, representative sampling of isolates from disperse geographic regions, including historically under-sampled areas. We also highlight the value of genomics in resolving antigenic and epidemiological variations within a serotype, which may have implications for future vaccine development.

Association of Laboratory Methods, Colonization Density, and Age With Detection of Streptococcus pneumoniae in the Nasopharynx.

Culture-based methods for detecting Streptococcus pneumoniae in the nasopharynx lack sensitivity. In this study, we aimed to compare the performance of culture and molecular methods in detecting pneumococcus in the nasopharynx of healthy individuals and to evaluate the associations of age and colonization density with detection. Between 2010 and 2012, nasopharyngeal specimens were collected from healthy individuals living on Navajo Nation and White Mountain Apache Tribal lands in the United States. Pneumococci were detected by means of broth-enrichment culture and autolysin-encoding gene (lytA) quantitative polymerase chain reaction (qPCR). Among 982 persons evaluated (median age, 18.7 years; 47% male), 35% were culture-positive and an additional 27% were qPCR-positive. Agreement between culture and qPCR was 70.9% but was higher among children (age <18 years) (75.9%-84.4%) than among adults (age ≥18 years) (61.0%-74.6%). The mean density of colonization was lower for culture-negative samples (3.14 log10 copies/mL) than for culture-positive samples (5.02 log10 copies/mL), overall and for all age groups. The percent culture-positive increased with increasing density, exceeding 80% at densities of ≥10,000 copies/mL. Mean colonization density decreased with age. Use of qPCR improved detection of pneumococcus in the nasopharynx of healthy individuals. This finding was most notable among adults, probably because of improved detection of low-density colonization.

Water quality, availability, and acute gastroenteritis on the Navajo Nation - a pilot case-control study.

The Navajo Nation includes approximately 250,000 American Indians living in a remote high desert environment with limited access to public water systems. We conducted a pilot case-control study to assess associations between acute gastroenteritis (AGE) and water availability, use patterns, and quality. Case patients with AGE and non-AGE controls who presented for care to two Indian Health Service hospitals were recruited. Data on demographics and water use practices were collected using a standard questionnaire. Household drinking water was tested for presence of pathogens, coliforms, and residual chlorine. Sixty-one subjects (32 cases and 29 controls) participated in the study. Cases and controls were not significantly different with respect to water sources, quality, or patterns of use. Twenty-one percent (n = 12) of study participants resided in dwellings not connected to a community water system. Eleven percent (n = 7) of subjects reported drinking hauled water from unregulated sources. Coliform bacteria were present in 44% (n = 27) of household water samples, and 68% (n = 40) of samples contained residual chlorine concentrations of <0.2 mg/L. This study highlights issues with water availability, quality, and use patterns within the Navajo Nation, including sub-optimal access to community water systems, and use of water hauled from unregulated sources.

Association of Pneumococcal Protein Antigen Serology With Age and Antigenic Profile of Colonizing Isolates.

Background: Several Streptococcus pneumoniae proteins play a role in pathogenesis and are being investigated as vaccine targets. It is largely unknown whether naturally acquired antibodies reduce the risk of colonization with strains expressing a particular antigenic variant. Methods: Serum immunoglobulin G (IgG) titers to 28 pneumococcal protein antigens were measured among 242 individuals aged <6 months-78 years in Native American communities between 2007 and 2009. Nasopharyngeal swabs were collected >- 30 days after serum collection, and the antigen variant in each pneumococcal isolate was determined using genomic data. We assessed the association between preexisting variant-specific antibody titers and subsequent carriage of pneumococcus expressing a particular antigen variant. Results: Antibody titers often increased across pediatric groups before decreasing among adults. Individuals with low titers against group 3 pneumococcal surface protein C (PspC) variants were more likely to be colonized with pneumococci expressing those variants. For other antigens, variant-specific IgG titers do not predict colonization. Conclusion: We observed an inverse association between variant-specific antibody concentration and homologous pneumococcal colonization for only 1 protein. Further assessment of antibody repertoires may elucidate the nature of antipneumococcal antibody-mediated mucosal immunity while informing vaccine development.

Streptococcus pneumoniae serotype 3 population structure in the era of conjugate vaccines, 2001-2018.

Background. Despite use of highly effective conjugate vaccines, invasive pneumococcal disease (IPD) remains a leading cause of morbidity and mortality and disproportionately affects Indigenous populations. Although included in the 13-valent pneumococcal conjugate vaccine (PCV13), which was introduced in 2010, serotype 3 continues to cause disease among Indigenous communities in the Southwest USA. In the Navajo Nation, serotype 3 IPD incidence increased among adults (3.8/100 000 in 2001-2009 and 6.2/100 000 in 2011-2019); in children the disease persisted although the rates dropped from 5.8/100 000 to 2.3/100 000.Methods. We analysed the genomic epidemiology of serotype 3 isolates collected from 129 adults and 63 children with pneumococcal carriage (n=61) or IPD (n=131) from 2001 to 2018 of the Navajo Nation. Using whole-genome sequencing data, we determined clade membership and assessed changes in serotype 3 population structure over time.Results. The serotype 3 population structure was characterized by three dominant subpopulations: clade II (n=90, 46.9 %) and clade Iα (n=59, 30.7 %), which fall into Clonal Complex (CC) 180, and a non-CC180 clade (n=43, 22.4 %). The proportion of clade II-associated IPD cases increased significantly from 2001 to 2010 to 2011-2018 among adults (23.1-71.8 %; P<0.001) but not in children (27.3-33.3 %; P=0.84). Over the same period, the proportion of clade II-associated carriage increased; this was statistically significant among children (23.3-52.6 %; P=0.04) but not adults (0-50.0 %, P=0.08).Conclusions. In this setting with persistent serotype 3 IPD and carriage, clade II has increased since 2010. Genomic changes may be contributing to the observed trends in serotype 3 carriage and disease over time.

A specific, accurate, and sensitive measure of total plasma malondialdehyde by HPLC.

Malondialdehyde (MDA) is one of the most commonly reported biomarkers of lipid peroxidation in clinical studies. The reaction of thiobarbituric acid (TBA) with MDA to yield a pink chromogen attributable to an MDA-TBA2 adduct is a common assay approach with products being quantified by ultraviolet-Vis assay as nonspecific TBA-reactive substances (TBARS) or chromatographically as MDA. The specificity of the TBARS assay was compared with both chromatographic assays for total plasma MDA. The levels of total plasma MDA were significantly lower than the plasma TBARS in each of the samples examined, and interestingly, the interindividual variation apparent in the level of plasma MDA was not evident in the plasma TBARS assay. Each of the four online chromatographic detectors yielded a precise, sensitive, and accurate determination of total plasma MDA, and selected-ion monitoring was the most-accurate assay (101.3%, n = 4). The online diode array detectors provided good assay specificity (peak purity index of 999), sensitivity, precision, and accuracy. This research demonstrates the inaccuracy that is inherent in plasma TBARS assays, which claim to quantify MDA, and it is proposed that the TBARS approach may limit the likelihood of detecting true differences in the level of lipid peroxidation in clinical studies.

Lack of nonspecific protection against all-cause nonrotavirus gastroenteritis by vaccination with orally administered rotavirus vaccine.

OBJECTIVES: Acute gastroenteritis (AGE) is recognized as a global, common threat to child survival, especially in developing countries. Rotavirus, in particular, has been implicated as a leading cause of severe AGE; however, there are numerous other pathogens that also cause AGE. Several studies have demonstrated that oral vaccination against rotavirus has generated the unanticipated benefit of protecting against AGE caused by nonrotavirus pathogens. METHODS: Safety and efficacy of the pentavalent bovine-human reassortant rotavirus vaccine were studied in multiple populations, including children of the Navajo and White Mountain Apache tribes in the southwestern United States. Stool specimens were collected from children with AGE and tested for rotavirus using an enzyme immunoassay. Analyses were conducted to detect the presence or absence of a vaccine effect on incidence, severity, and duration of AGE in which rotavirus was not detected. RESULTS: The majority of AGE (N = 558: 472 nonrotavirus vs 86 rotavirus) occurred between August 2002 and March 2004 among children ranging from ages 4 to 23 months. The incidence of nonrotavirus AGE was similar by vaccine groups with an incidence rate ratio of 1.07 (incidence rate ratio = vaccinated/unvaccinated, 95% confidence interval 0.89-1.29). The hazards of first, second, third, or any AGE in which rotavirus was not detected differed little by vaccination status (P > 0.05). Duration of symptoms and severity of nonrotavirus AGE were similar by vaccine group. CONCLUSIONS: There was no vaccine effect on frequency or severity of nonrotavirus AGE.

Nontypeable pneumococcal isolates among navajo and white mountain apache communities: are these really a cause of invasive disease?

BACKGROUND: Pneumococci could evade pneumococcal conjugate vaccines (PCV) by modifying, mutating, or deleting vaccine-serotype capsule genes or by downregulating capsule production. We sought to assess whether pneumococci that are nontypeable (NT) by the Quellung reaction truly lack capsule genes or are failing to produce capsule in vitro. METHODS: We applied multilocus sequence typing and a microarray for detection of pneumococcal polysaccharide capsule biosynthesis genes to NT carriage (children aged <5 years; years 1997-2000, 2006-2008) and NT invasive disease (IPD) (all ages; years 1994-2007) isolates from Native American communities. RESULTS: Twenty-seven of 28 (96.4%) NT IPD isolates had sequence types (STs) typically found among typeable IPD isolates and contained whole or fragments of capsule genes that matched known serotypes; 1 NT-IPD isolate had a profile resembling NT carriage isolates. Forty-nine of 76 (64.5%) NT carriage isolates had STs that typically lack capsule genes and were similar to NT carriage isolates found globally. CONCLUSIONS: This is the first documentation of IPD from an NT strain confirmed to lack all known capsule genes. Most NT IPD isolates have or had the capacity to produce capsule, whereas a majority of NT carriage isolates lack this capacity. We found no evidence of pneumococcal adaptation to PCV7 via downregulation or deletion of vaccine-serotype capsule genes.

Impact of more than a decade of pneumococcal conjugate vaccine use on carriage and invasive potential in Native American communities.

BACKGROUND: We assessed the impact of 12 years of pneumococcal conjugate vaccine (PCV7) use on pneumococcal nasopharyngeal carriage and serotype-specific invasive disease potential among Native Americans. METHODS: Families were enrolled in a carriage study from 2006 to 2008; nasopharyngeal specimens and risk factor information were collected monthly for 7 visits. Pneumococcal carriage prevalence was compared with that before (1998-2000) and during (2001-2002) PCV7 introduction. We compared invasive disease incidence and carriage prevalence before and after PCV7 introduction to estimate changes in serotype-specific invasive potential. RESULTS: We enrolled 1077 subjects from 302 households. There was an absolute reduction in carriage prevalence of 8.0% (95% confidence interval [CI], 4.5%-11.4%) in children aged <5 years and 3.1% (95% CI, 1.1%-5.1%) in adults. In children aged <5 years, vaccine-serotype carriage prevalence decreased by 22.8% (95% CI, 20.1%-25.3%), and nonvaccine serotype (NVT) increased by 15.9% (95% CI, 12.4%-19.3%). No significant change was detected in serotype-specific invasive potential after PCV7 introduction. CONCLUSIONS: Pneumococcal carriage prevalence decreased in all ages since PCV7 introduction; vaccine-serotype carriage has been nearly eliminated, whereas the prevalence of NVT carriage has increased. The increase in the NVT invasive disease rate seems to be proportional to the increase in colonization prevalence.

Epidemiologic and clinical features of other enteric viruses associated with acute gastroenteritis in American Indian infants.

OBJECTIVE: To investigate the viral etiology, through the use of molecular methods, of acute gastroenteritis (AGE), which is a considerable public health burden in Native American infants. STUDY DESIGN: From March 2002 through February 2004, AGE and non-diarrheal stools were collected from Navajo and White Mountain Apache infants who received placebo during a rotavirus vaccine trial. Case (n=247) and control (n=344) specimens were tested for enteric adenovirus, astrovirus, norovirus, rotavirus, and sapovirus with real-time polymerase chain reaction. The odds of AGE were compared with population-averaged logistic regression models. RESULTS: In 65% of the cases of AGE (161/247), at least one virus was detected; norovirus (n=80, 32%) and rotavirus (n=70, 28%) were the most common. A virus was detected in 38% of control specimens (132/344). Detection of "any virus" was associated with AGE (OR=3.22; 95% CI, 2.11-4.91), as was detection of norovirus (OR=2.00; 95% CI, 1.22-3.26) and rotavirus (OR=2.69; 95% CI, 1.52-4.79). CONCLUSION: This study highlights the significant burden of viral AGE in American Indian infants and identifies pathogen targets for future prevention efforts in this population.

The Family Spirit trial for American Indian teen mothers and their children: CBPR rationale, design, methods and baseline characteristics.

The purpose of this paper is to describe the rationale, design, methods and baseline results of the Family Spirit trial. The goal of the trial is to evaluate the impact of the paraprofessional-delivered "Family Spirit" home-visiting intervention to reduce health and behavioral risks for American Indian teen mothers and their children. A community based participatory research (CBPR) process shaped the design of the current randomized controlled trial of the Family Spirit intervention. Between 2006 and 2008, 322 pregnant teens were randomized to receive the Family Spirit intervention plus Optimized Standard Care, or Optimized Standard Care alone. The Family Spirit intervention is a 43-session home-visiting curriculum administered by American Indian paraprofessionals to teen mothers from 28 weeks gestation until the baby's third birthday. A mixed methods assessment administered at nine intervals measures intervention impact on parental competence, mother's and children's social, emotional and behavioral risks for drug use, and maladaptive functioning. Participants are young (mean age = 18.1 years), predominantly primiparous, unmarried, and challenged by poverty, residential instability and low educational attainment. Lifetime and pregnancy drug use were ~2-4 times higher and ~5-6 times higher, respectively, than US All Races. Baseline characteristics were evenly distributed between groups, except for higher lifetime cigarette use and depressive symptoms among intervention mothers. If study aims are achieved, the public health field will have new evidence supporting multi-generational prevention of behavioral health disparities affecting young American Indian families and the utility of indigenous paraprofessional interventionists in under-resourced communities.

Evaluation of indoor PM2.5 concentrations in a Native American Community: a pilot study.

BACKGROUND: Indoor air pollution is associated with adverse health effects; however, few studies exist studying indoor air pollution on the Navajo Nation in the southwest U.S., a community with high rates of respiratory disease. METHODS: Indoor PM2.5 concentration was evaluated in 26 homes on the Navajo Nation using real-time PM2.5 monitors. Household risk factors and daily activities were evaluated with three metrics of indoor PM2.5: time-weighted average (TWA), 90th percentile of concentration, and daily minutes exceeding 100 µg/m3. A questionnaire and recall sheet were used to record baseline household characteristics and daily activities. RESULTS: The median TWA, 90th percentile, and daily minutes exceeding 100 µg/m3 were 7.9 µg/m3, 14.0 µg/m3, and 17 min, respectively. TWAs tended to be higher in autumn and in houses that used fuel the previous day. Other characteristics associated with elevated PM exposure in all metrics included overcrowded houses, nonmobile houses, and houses with current smokers, pets, and longer cooking time. CONCLUSIONS: Some residents of the Navajo Nation have higher risk of exposure to indoor air pollution by Environmental Protection Agency (EPA) standards. Efforts to identify the causes and associations with adverse health effects are needed to ensure that exposure to risks and possible health impacts are mitigated.

Detection of G3P[3] and G3P[9] rotavirus strains in American Indian children with evidence of gene reassortment between human and animal rotaviruses.

The distribution and evolution of human rotavirus strains is important for vaccine development and effectiveness. In settings where rotavirus vaccine coverage is high, vaccine pressure could select for replacement of common strains (similar to those included in rotavirus vaccines) with uncommon strains, some of which could be generated by reassortment between human and animal rotaviruses. Between 2002 and 2004, a phase-III rotavirus vaccine clinical trial was conducted among American Indian children of the Navajo and White Mountain Apache tribes, which are known to be at high risk for rotavirus diarrhea. We evaluated the rotavirus strains collected from study participants who received placebo during the trial to determine the distribution of rotavirus genotypes and to detect emerging strains that contribute to disease and could influence rotavirus vaccine effectiveness. Three uncommon strains of human rotavirus, two G3P[3] and one G3P[9] strains were detected in stools of children aged 3 to 6 months of age. Segments of all 11 rotavirus genes were sequenced and genotyped by comparison of cognate gene fragments with reference strains. The G3P[3] strains had similar genotypes to each other and to reference dog and cat strains. The G3P[9] strain had similar genotypes to cow, cat and dog reference strains. Genetic analyses of these three strains support the known diversity generating mechanisms of rotavirus.

Empowering Native Adolescents: Responsibility for Their Health Behaviors.

Objectives: In this study, we assess the impact of a home-based diabetes prevention program, Together on Diabetes (TOD), on adolescent responsibility-taking for tasks related to diabetes risk. Methods: Participants were Native American youth ages 10-19 with or at risk of type 2 diabetes who participated in a 12-session, 6-month diabetes prevention program with an adult caretaker. Assessments completed at baseline, 6-month, and 12-month follow-up include demographics and the Diabetes and Obesity Task Sharing (DOTS) Questionnaire. We used latent class analysis (LCA) at baseline to examine heterogeneity in DOTS responses. We identified 3 classes (adolescent, shared, caretaker). We used latent transition analysis to examine stability and change in latent status at baseline, 6- and 12-month follow-up. Results: At baseline, the mean age of participants was 13.6 years and 55.9% were boys. From baseline to 6-month follow-up, the adolescent class was most stable, whereas the shared and caretaker classes were less stable. For participants who transition from the adolescent class, most transition to shared class compared to caretaker class. Conclusions: TOD helps to empower Native American adolescents to take responsibility for their health and engage with their caregivers in these decisions.

Centering the Strengths of American Indian Culture, Families and Communities to Overcome Type 2 Diabetes.

Type 2 diabetes (T2D) is a critical Indigenous health inequity rooted in experiences of colonization and marginalization including disproportionate exposure to stressors, disruption of traditional family and food systems, and attacks on cultural practices that have led to more sedentary lifestyles. Thus, an important step in redressing inequities is building awareness of and interventions attuned to unique Indigenous contexts influencing T2D and Indigenous culture as a pathway to community wellbeing. Using a dynamic, stage-based model of intervention development and evaluation, we detail the creation and evolution of a family-based, culturally centered T2D preventive intervention: Together on Diabetes (later Together Overcoming Diabetes) (TOD). The TOD program was built by and for Indigenous communities via community-based participatory research and has been implemented across diverse cultural contexts. The TOD curriculum approaches health through a holistic lens of spiritual, mental, physical and emotional wellness. Preliminary evidence suggests TOD is effective in reducing diabetes risk factors including lowering BMI and depressive symptoms, and the program is viewed favorably by participants and community members. We discuss lessons learned regarding collaborative intervention development and adaptation across Indigenous cultures, as well as future directions for TOD.

Effect of a Home-Visiting Intervention to Reduce Early Childhood Obesity Among Native American Children: A Randomized Clinical Trial.

Importance: Early childhood obesity disproportionately affects Native American communities. Home visiting is a promising strategy for promoting optimal infant growth in this population. Objective: To assess the impact of a brief home-visiting approach, Family Spirit Nurture (FSN), on sugar-sweetened beverage (SSB) consumption, responsive parenting and infant feeding practices, and optimal growth through 12 months post partum. Design, Setting, and Participants: This study was a 1:1 randomized clinical trial comparing FSN with an injury prevention education control condition in a reservation-based community. Participants were Navajo mothers 13 years or older with infants younger than 14 weeks recruited between March 22, 2017, and May 18, 2018, and followed up through 12 months post partum. Intent-to-treat analyses were conducted. Interventions: The 6-lesson FSN curriculum, delivered 3 to 6 months post partum by Navajo paraprofessionals, targeted optimal responsive and complementary feeding practices and avoidance of SSBs. The control group received 3 injury prevention lessons. Main Outcomes and Measures: Primary outcomes established a priori were infant SSB consumption and responsive parenting and complementary feeding practices (responsive feeding scale, age at complementary food introduction, and percentage of mothers who introduced complementary food to infants at 6 months of age or older). The secondary outcome was the effect of the intervention on infant body mass index z scores (zBMIs). Results: A total of 134 Navajo mothers of infants younger than 14 weeks were enrolled in the randomized clinical trial, including 68 (mean [SD] maternal age at enrollment, 27.4 [6.4] years) in the intervention group and 66 (mean [SD] maternal age at enrollment, 27.5 [6.1] years) in the control group. Intervention participants reported statistically significantly lower infant SSB consumption through 12 months post partum (mean [SE], 0.56 [0.12] cups per week in the intervention group and 1.78 [0.18] cups per week in the control group; incidence rate ratio, 0.31; 95% CI, 0.19-0.50). Improvements in responsive feeding practices were observed through 9 months post partum (mean [SE], 3.48 [0.07] in the intervention group and 3.22 [0.08] in the control group) (difference, 0.26; 95% CI, 0.06-0.47); statistical significance was lost at 12 months post partum. Age at which the infant was given first food was younger in the intervention group (mean [SE] age, 4.61 [0.21] months in the intervention group and 5.28 [0.23] months in the control group) (difference, -0.67; 95% CI, -0.04 to -1.29). Infants in the intervention group had lower zBMI at 6 and 9 months compared with those in the control group (mean [SE] at 9 months, 0.27 [0.14] in the intervention group and 0.81 [0.14] in the control group; difference, -0.54; 95% CI, -0.94 to -0.14). The 12-month between-group difference was meaningful but not statistically significant (mean [SE], 0.61 [0.16] in the intervention group and 1.07 [0.20] in the control group; difference, -0.46; 95% CI, -0.92 to 0.01). Conclusions and Relevance: Infants of Native American mothers who participated in a home-visiting intervention had substantially lower SSB consumption and improvements in responsive feeding practices and infant zBMI scores, suggesting the intervention is effective for promoting healthy infant feeding and growth. Trial Registration: ClinicalTrials.gov Identifier: NCT03101943.