@article {1391, title = {Assessment of spillover of antimicrobial resistance to untreated children 7 to 12 years old after mass drug administration of azithromycin for child survival in Niger: a secondary analysis of the MORDOR cluster-randomized trial.}, journal = {Clin Infect Dis}, year = {2024}, month = {2024 May 13}, abstract = {

BACKGROUND: The risk of antibiotic resistance is complicated by the potential for spillover effects from one treated population to another. Azithromycin mass drug administration programs report higher rates of antibiotic resistance among treatment arms in targeted groups. This study aims to understand the risk of spillover of antibiotic resistance to non-target groups in these programs.

METHODS: Data was used from a cluster-randomized trial comparing the effect of biannual azithromycin and placebo distribution to children 1-59 months on child mortality. Nasopharyngeal samples from untreated children 7-12 years old were tested for genetic determinants of macrolide resistance (primary outcome) and resistance to other antibiotic classes (secondary outcomes). Linear regression was used to compare the community-level mean difference in prevalence by arm at the 24-month timepoint adjusting for baseline prevalence.

RESULTS: 1,103 children 7-12 years old in 30 communities were included in the analysis (15 azithromycin, 15 placebo). Adjusted mean differences in prevalence of resistance determinants for macrolides, beta-lactams and tetracyclines were 3.4\% (95\% CI -4.1\% to 10.8\%, P-value 0.37), -1.2\% (95\% CI -7.9\% to 5.5\%, P-value 0.72), and -3.3\% (95\% CI -9.5\% to 2.8\%, P-value 0.61), respectively.

CONCLUSIONS: We were unable to demonstrate a statistically significant increase in macrolide resistance determinants in untreated groups in an azithromycin mass drug administration program. While the result might be consistent with a small spillover effect, this study was not powered to detect such a small difference. Larger studies are warranted to better understand the potential for spillover effects within these programs.

}, issn = {1537-6591}, doi = {10.1093/cid/ciae267}, author = {Peterson, Brittany and Arzika, Ahmed M and Amza, Abdou and Maliki, Ramatou and Mankara Karamba, Alio and Moussa, Mariama and Kemago, Mariama and Liu, Zijun and Houpt, Eric and Liu, Jie and Pholwat, Suporn and Doan, Thuy and Porco, Travis and Keenan, Jeremy D and Lietman, Thomas M and O{\textquoteright}Brien, Kieran S} } @article {1381, title = {Prolonged mass azithromycin distributions and macrolide resistance determinants among preschool children in Niger: A sub-study of a cluster-randomized trial (MORDOR).}, journal = {PLoS Med}, volume = {21}, year = {2024}, month = {2024 May}, pages = {e1004386}, abstract = {

BACKGROUND: Randomized controlled trials found that twice-yearly mass azithromycin administration (MDA) reduces childhood mortality, presumably by reducing infection burden. World Health Organization (WHO) issued conditional guidelines for mass azithromycin administration in high-mortality settings in sub-Saharan Africa given concerns for antibiotic resistance. While prolonged twice-yearly MDA has been shown to increase antibiotic resistance in small randomized controlled trials, the objective of this study was to determine if macrolide and non-macrolide resistance in the gut increases with the duration of azithromycin MDA in a larger setting.

METHODS AND FINDINGS: The Macrolide Oraux pour R{\'e}duire les D{\'e}c{\`e}s avec un Oeil sur la R{\'e}sistance (MORDOR) study was conducted in Niger from December 2014 to June 2020. It was a cluster-randomized trial of azithromycin (A) versus placebo (P) aimed at evaluating childhood mortality. This is a sub-study in the MORDOR trial to track changes in antibiotic resistance after prolonged azithromycin MDA. A total of 594 communities were eligible. Children 1 to 59 months in 163 randomly chosen communities were eligible to receive treatment and included in resistance monitoring. Participants, staff, and investigators were masked to treatment allocation. At the conclusion of MORDOR Phase I, by design, all communities received an additional year of twice-yearly azithromycin treatments (Phase II). Thus, at the conclusion of Phase II, the treatment history (1 letter per 6-month period) for the participating communities was either (PP-PP-AA) or (AA-AA-AA). In Phase III, participating communities were then re-randomized to receive either another 3 rounds of azithromycin or placebo, thus resulting in 4 treatment histories: Group 1 (AA-AA-AA-AA-A, N = 51), Group 2 (PP-PP-AA-AA-A, N = 40), Group 3 (AA-AA-AA-PP-P, N = 27), and Group 4 (PP-PP-AA-PP-P, N = 32). Rectal swabs from each child (N = 5,340) were obtained 6 months after the last treatment. Each child contributed 1 rectal swab and these were pooled at the community level, processed for DNA-seq, and analyzed for genetic resistance determinants. The primary prespecified outcome was macrolide resistance determinants in the gut. Secondary outcomes were resistance to beta-lactams and other antibiotic classes. Communities recently randomized to azithromycin (groups 1 and 2) had significantly more macrolide resistance determinants than those recently randomized to placebo (groups 3 and 4) (fold change 2.18, 95\% CI 1.5 to 3.51, Punadj \< 0.001). However, there was no significant increase in macrolide resistance in communities treated 4.5 years (group 1) compared to just the most recent 2.5 years (group 2) (fold change 0.80, 95\% CI 0.50 to 1.00, Padj = 0.010), or between communities that had been treated for 3 years in the past (group 3) versus just 1 year in the past (group 4) (fold change 1.00, 95\% CI 0.78 to 2.35, Padj = 0.52). We also found no significant differences for beta-lactams or other antibiotic classes. The main limitations of our study were the absence of phenotypic characterization of resistance, no complete placebo arm, and no monitoring outside of Niger limiting generalizability.

CONCLUSIONS: In this study, we observed that mass azithromycin distribution for childhood mortality among preschool children in Niger increased macrolide resistance determinants in the gut but that resistance may plateau after 2 to 3 years of treatment. Co-selection to other classes needs to be monitored.

TRIAL REGISTRATION: NCT02047981 https://classic.clinicaltrials.gov/ct2/show/NCT02047981.

}, keywords = {Anti-Bacterial Agents, Azithromycin, Child Mortality, Child, Preschool, Drug Resistance, Bacterial, Female, Humans, Infant, Macrolides, Male, Mass Drug Administration, Niger}, issn = {1549-1676}, doi = {10.1371/journal.pmed.1004386}, author = {Arzika, Ahmed M and Abdou, Amza and Maliki, Ramatou and Beido, Nassirou and Kadri, Boubacar and Harouna, Abdoul N and Galo, Abdoul N and Alio, Mankara K and Lebas, Elodie and Oldenburg, Catherine E and O{\textquoteright}Brien, Kieran S and Chen, Cindi and Zhong, Lina and Zhou, Zhaoxia and Yan, Daisy and Hinterwirth, Armin and Keenan, Jeremy D and Porco, Travis C and Lietman, Thomas M and Doan, Thuy} } @article {1291, title = {Temporal Trends in Phenotypic Macrolide and Nonmacrolide Resistance for Streptococcus pneumoniae Nasopharyngeal Samples Up to 36 Months after Mass Azithromycin Administration in a Cluster-Randomized Trial in Niger.}, journal = {Am J Trop Med Hyg}, year = {2023}, month = {2023 Oct 02}, abstract = {

Azithromycin mass drug administration decreases child mortality but also selects for antibiotic resistance. Herein, we evaluate macrolide resistance of nasopharyngeal Streptococcus pneumoniae after azithromycin MDA. In a cluster-randomized trial, children 1-59 months received azithromycin or placebo biannually. Fifteen villages from each arm were randomly selected for antimicrobial resistance testing, and 10-15 randomly selected swabs from enrolled children at each village were processed for S. pneumoniae isolation and resistance testing. The primary prespecified outcome was macrolide resistance fraction for azithromycin versus placebo villages at 36 months. Secondary non-prespecified outcomes were comparisons of azithromycin and placebo for: 1) macrolide resistance at 12, 24, and 36 months; 2) nonmacrolide resistance at 36 months; and 3) suspected-erm mutation. At 36 months, 423 swabs were obtained and 322 grew S. pneumoniae, (azithromycin: 146/202, placebo: 176/221). Mean resistance prevalence was non-significantly higher in treatment than placebo (mixed-effects model: 14.6\% vs. 8.9\%; OR = 2.0, 95\%CI: 0.99-3.97). However, when all time points were evaluated, macrolide resistance prevalence was significantly higher in the azithromycin group (β = 0.102, 95\%CI: 0.04-0.167). For all nonmacrolides, resistance prevalence at 36 months was not different between the two groups. Azithromycin and placebo were not different for suspected-erm mutation prevalence. Macrolide resistance was higher in the azithromycin group over all time points, but not at 36 months. Although this suggests resistance may not continue to increase after biannual MDA, more studies are needed to clarify when MDA can safely decrease mortality and morbidity in lower- and middle-income countries.

}, issn = {1476-1645}, doi = {10.4269/ajtmh.23-0431}, author = {Hazel, Ashley and Arzika, Ahmed M and Abdou, Amza and Lebas, Elodie and Porco, Travis C and Maliki, Ramatou and Doan, Thuy and Lietman, Thomas M and Keenan, Jeremy D and Blumberg, Seth} } @article {1281, title = {Wastewater-Based Surveillance of Antimicrobial Resistance in Niger: An Exploratory Study.}, journal = {Am J Trop Med Hyg}, year = {2023}, month = {2023 Aug 28}, abstract = {

Wastewater-based surveillance is increasingly recognized as an important approach to monitoring population-level antimicrobial resistance (AMR). In this exploratory study, we examined the use of metagenomics to evaluate AMR using untreated wastewater samples routinely collected by the Niger national polio surveillance program. Forty-eight stored samples from two seasons each year over 4 years (2016-2019) in three regions were selected for inclusion in this study and processed using unbiased DNA deep sequencing. Normalized number of reads of genetic determinants for different antibiotic classes were compared over time, by season, and by location. Correlations in resistance were examined among classes. Changes in reads per million per year were demonstrated for several classes, including decreases over time in resistance determinants for phenicols (-3.3, 95\% CI: -8.7 to -0.1, P = 0.029) and increases over time for aminocoumarins (3.8, 95\% CI: 0.0 to 11.4, P = 0.043), fluoroquinolones (6.8, 95\% CI: 0.0 to 20.5, P = 0.048), and beta-lactams (0.85, 95\% CI: 0.1 to 1.7, P = 0.006). Sulfonamide resistance was higher in the post-rainy season compared with the dry season (5.2-fold change, 95\% CI: 3.4 to 7.9, P < 0.001). No differences were detected when comparing other classes by season or by site for any antibiotic class. Positive correlations were identified in genetic determinants of resistance among several antibiotic classes. These results demonstrate the potential utility of leveraging existing wastewater sample collection in this setting for AMR surveillance.

}, issn = {1476-1645}, doi = {10.4269/ajtmh.23-0204}, author = {Ousmane, Sani and Kollo, Issifi A and Jambou, Ronan and Boubacar, Rakia and Arzika, Ahmed M and Maliki, Ramatou and Amza, Abdou and Liu, Zijun and Lebas, Elodie and Colby, Emily and Zhong, Lina and Chen, Cindi and Hinterwirth, Armin and Doan, Thuy and Lietman, Thomas M and O{\textquoteright}Brien, Kieran S} } @article {931, title = {Effect of biannual azithromycin distribution on antibody responses to malaria, bacterial, and protozoan pathogens in Niger.}, journal = {Nat Commun}, volume = {13}, year = {2022}, month = {2022 02 21}, pages = {976}, abstract = {

The MORDOR trial in Niger, Malawi, and Tanzania found that biannual mass distribution of azithromycin to children younger than 5 years led to a 13.5\% reduction in all-cause mortality (NCT02048007). To help elucidate the mechanism for mortality reduction, we report IgG responses to 11 malaria, bacterial, and protozoan pathogens using a multiplex bead assay in pre-specified substudy of 30 communities in the rural Niger placebo-controlled trial over a three-year period (n = 5642 blood specimens, n = 3814 children ages 1-59 months). Mass azithromycin reduces Campylobacter spp. force of infection by 29\% (hazard ratio = 0.71, 95\% CI: 0.56, 0.89; P = 0.004) but serological measures show no significant differences between groups for other pathogens against a backdrop of high transmission. Results align with a recent microbiome study in the communities. Given significant sequelae of Campylobacter infection among preschool aged children, our results support an important mechanism through which biannual mass distribution of azithromycin likely reduces mortality in Niger.

}, issn = {2041-1723}, doi = {10.1038/s41467-022-28565-5}, author = {Arzika, Ahmed M and Maliki, Ramatou and Goodhew, E Brook and Rogier, Eric and Priest, Jeffrey W and Lebas, Elodie and O{\textquoteright}Brien, Kieran S and Le, Victoria and Oldenburg, Catherine E and Doan, Thuy and Porco, Travis C and Keenan, Jeremy D and Lietman, Thomas M and Martin, Diana L and Arnold, Benjamin F} } @article {911, title = {Age-based targeting of biannual azithromycin distribution for child survival in Niger: an adaptive cluster-randomized trial protocol (AVENIR).}, journal = {BMC Public Health}, volume = {21}, year = {2021}, month = {2021 04 29}, pages = {822}, abstract = {

BACKGROUND: Biannual distribution of azithromycin to children 1-59 months old reduced mortality by 14\% in a cluster-randomized trial. The World Health Organization has proposed targeting this intervention to the subgroup of children 1-11 months old to reduce selection for antimicrobial resistance. Here, we describe a trial designed to determine the impact of age-based targeting of biannual azithromycin on mortality and antimicrobial resistance.

METHODS: AVENIR is a cluster-randomized, placebo-controlled, double-masked, response-adaptive large simple trial in Niger. During the 2.5-year study period, 3350 communities are targeted for enrollment. In the first year, communities in the Dosso region will be randomized 1:1:1 to 1) azithromycin 1-11: biannual azithromycin to children 1-11 months old with placebo to children 12-59 months old, 2) azithromycin 1-59: biannual azithromycin to children 1-59 months old, or 3) placebo: biannual placebo to children 1-59 months old. Regions enrolled after the first year will be randomized with an updated allocation based on the probability of mortality in children 1-59 months in each arm during the preceding study period. A biannual door-to-door census will be conducted to enumerate the population, distribute azithromycin and placebo, and monitor vital status. Primary mortality outcomes are defined as all-cause mortality rate (deaths per 1000 person-years) after 2.5 years from the first enrollment in 1) children 1-59 months old comparing the azithromycin 1-59 and placebo arms, 2) children 1-11 months old comparing the azithromycin 1-11 and placebo arm, and 3) children 12-59 months in the azithromycin 1-11 and azithromycin 1-59 arms. In the Dosso region, 50 communities from each arm will be followed to monitor antimicrobial resistance. Primary resistance outcomes will be assessed after 2 years of distributions and include 1) prevalence of genetic determinants of macrolide resistance in nasopharyngeal samples from children 1-59 months old, and 2) load of genetic determinants of macrolide resistance in rectal samples from children 1-59 months old.

DISCUSSION: As high-mortality settings consider this intervention, the results of this trial will provide evidence to support programmatic and policy decision-making on age-based strategies for azithromycin distribution to promote child survival.

TRIAL REGISTRATION: This trial was registered on January 13, 2020 (clinicaltrials.gov: NCT04224987 ).

}, keywords = {Anti-Bacterial Agents, Azithromycin, Child, Child, Preschool, Drug Resistance, Bacterial, Humans, Infant, Macrolides, Mass Drug Administration, Niger, Randomized Controlled Trials as Topic}, issn = {1471-2458}, doi = {10.1186/s12889-021-10824-7}, author = {O{\textquoteright}Brien, Kieran S and Arzika, Ahmed M and Amza, Abdou and Maliki, Ramatou and Ousmane, Sani and Kadri, Boubacar and Nassirou, Beido and Mankara, Alio Karamba and Harouna, Abdoul Naser and Colby, Emily and Lebas, Elodie and Liu, Zijun and Le, Victoria and Nguyen, William and Keenan, Jeremy D and Oldenburg, Catherine E and Porco, Travis C and Doan, Thuy and Arnold, Benjamin F and Lietman, Thomas M} } @article {821, title = {Gut resistome of preschool children after prolonged mass azithromycin distribution: a cluster-randomized trial.}, journal = {Clin Infect Dis}, year = {2021}, month = {2021 May 26}, abstract = {

We evaluated the gut resistome of children from communities treated with 10 twice-yearly azithromycin distributions. While the macrolide resistance remained higher in the azithromycin arm, the selection of non-macrolide resistance observed at earlier time points did not persist. Longitudinal resistance monitoring should be a critical component of mass distribution programs.

}, issn = {1537-6591}, doi = {10.1093/cid/ciab485}, author = {Arzika, Ahmed M and Maliki, Ramatou and Abdou, Amza and Mankara, Alio K and Harouna, Abdoul N and Cook, Catherine and Hinterwirth, Armin and Worden, Lee and Zhong, Lina and Chen, Cindi and Ruder, Kevin and Zhou, Zhaoxia and Lebas, Elodie and O{\textquoteright}Brien, Kieran S and Oldenburg, Catherine E and Le, Victoria and Arnold, Benjamin F and Porco, Travis and Keenan, Jeremy D and Lietman, Thomas M and Doan, Thuy} } @article {161, title = {Gut Bacterial Diversity and Growth among Preschool Children in Burkina Faso.}, journal = {Am J Trop Med Hyg}, volume = {103}, year = {2020}, month = {2020 12}, pages = {2568-2573}, abstract = {

There is a lack of empirical, prospective human data on the gut microbiome and its relationship with growth, especially in low- and middle-income countries. We prospectively assessed the association between gut microbial diversity and short-term growth in a cohort of preschool children in Burkina Faso to better characterize whether there is any evidence that changes in gut microbial diversity may affect growth. Data were obtained from a randomized controlled trial evaluating the effect of antibiotic administration on gut microbial diversity in preschool children. We followed up the enrolled children for 35 days, with anthropometric measurements at baseline and day 35 and microbial diversity measured at baseline and day 9 (analytic sample, = 155). We estimated linear mixed-effects regression models with household random intercepts to assess the association of Simpson{\textquoteright}s and Shannon{\textquoteright}s alpha diversity with measures of change in anthropometry (e.g., ponderal growth since baseline) and absolute anthropometric measurements (e.g., day 35 weight). We did not find evidence that alpha gut microbial diversity was associated with growth or absolute anthropometric measurements after adjusting for confounding variables. Effect estimates were close to the null ( >= 0.15 for all fully adjusted comparisons), with the association between Simpson{\textquoteright}s alpha diversity and day 35 height (cm) farthest from the null (coefficient = -0.03, 95\% CI: -0.07, 0.01). The change in gut microbial diversity also was not associated with the change in anthropometry in crude or adjusted models. Future research is needed to explore whether gut diversity has an impact on growth over a longer time period, in both healthy and malnourished children.

}, keywords = {Anti-Bacterial Agents, Bacteria, Burkina Faso, Child Development, Child, Preschool, Female, Gastrointestinal Microbiome, Humans, Infant, Male, Nutritional Status, Prospective Studies}, issn = {1476-1645}, doi = {10.4269/ajtmh.20-0059}, author = {Digitale, Jean and Sie, Ali and Coulibaly, Boubacar and Ouermi, Lucienne and Dah, Clarisse and Tapsoba, Charlemagne and B{\"a}rnighausen, Till and Lebas, Elodie and Arzika, Ahmed M and Glymour, Medellena Maria and Keenan, Jeremy D and Doan, Thuy and Oldenburg, Catherine E} } @article {71, title = {Macrolide and Nonmacrolide Resistance with Mass Azithromycin Distribution.}, journal = {N Engl J Med}, volume = {383}, year = {2020}, month = {2020 11 12}, pages = {1941-1950}, abstract = {

BACKGROUND: Mass distribution of azithromycin to preschool children twice yearly for 2 years has been shown to reduce childhood mortality in sub-Saharan Africa but at the cost of amplifying macrolide resistance. The effects on the gut resistome, a reservoir of antimicrobial resistance genes in the body, of twice-yearly administration of azithromycin for a longer period are unclear.

METHODS: We investigated the gut resistome of children after they received twice-yearly distributions of azithromycin for 4 years. In the Niger site of the MORDOR trial, we enrolled 30 villages in a concurrent trial in which they were randomly assigned to receive mass distribution of either azithromycin or placebo, offered to all children 1 to 59 months of age every 6 months for 4 years. Rectal swabs were collected at baseline, 36 months, and 48 months for analysis of the participants{\textquoteright} gut resistome. The primary outcome was the ratio of macrolide-resistance determinants in the azithromycin group to those in the placebo group at 48 months.

RESULTS: Over the entire 48-month period, the mean ({\textpm}SD) coverage was 86.6{\textpm}12\% in the villages that received placebo and 83.2{\textpm}16.4\% in the villages that received azithromycin. A total of 3232 samples were collected during the entire trial period; of the samples obtained at the 48-month monitoring visit, 546 samples from 15 villages that received placebo and 504 from 14 villages that received azithromycin were analyzed. Determinants of macrolide resistance were higher in the azithromycin group than in the placebo group: 7.4 times as high (95\% confidence interval [CI], 4.0 to 16.7) at 36 months and 7.5 times as high (95\% CI, 3.8 to 23.1) at 48 months. Continued mass azithromycin distributions also selected for determinants of nonmacrolide resistance, including resistance to beta-lactam antibiotics, an antibiotic class prescribed frequently in this region of Africa.

CONCLUSIONS: Among villages assigned to receive mass distributions of azithromycin or placebo twice yearly for 4 years, antibiotic resistance was more common in the villages that received azithromycin than in those that received placebo. This trial showed that mass azithromycin distributions may propagate antibiotic resistance. (Funded by the Bill and Melinda Gates Foundation and others; ClinicalTrials.gov number, NCT02047981.).

}, keywords = {Anti-Bacterial Agents, Azithromycin, Child Mortality, Child, Preschool, Drug Resistance, Bacterial, Female, Gastrointestinal Microbiome, Humans, Infant, Macrolides, Male, Mass Drug Administration, Metagenome, Niger, Sequence Analysis, DNA}, issn = {1533-4406}, doi = {10.1056/NEJMoa2002606}, author = {Doan, Thuy and Worden, Lee and Hinterwirth, Armin and Arzika, Ahmed M and Maliki, Ramatou and Abdou, Amza and Zhong, Lina and Chen, Cindi and Cook, Catherine and Lebas, Elodie and O{\textquoteright}Brien, Kieran S and Oldenburg, Catherine E and Chow, Eric D and Porco, Travis C and Lipsitch, Marc and Keenan, Jeremy D and Lietman, Thomas M} } @article {86, title = {Post-antibiotic Ocular Surface Microbiome in Children: A Cluster-Randomized Trial.}, journal = {Ophthalmology}, volume = {127}, year = {2020}, month = {2020 08}, pages = {1127-1130}, keywords = {Anti-Bacterial Agents, Child, Cornea, Humans, Microbiota, Randomized Controlled Trials as Topic}, issn = {1549-4713}, doi = {10.1016/j.ophtha.2020.02.014}, author = {Doan, Thuy and Hinterwirth, Armin and Worden, Lee and Arzika, Ahmed M and Maliki, Ramatou and Chen, Cindi and Zhong, Lina and Zhou, Zhaoxia and Acharya, Nisha R and Porco, Travis C and Keenan, Jeremy D and Lietman, Thomas M} } @article {106, title = {Reduction of Coronavirus Burden With Mass Azithromycin Distribution.}, journal = {Clin Infect Dis}, volume = {71}, year = {2020}, month = {2020 11 19}, pages = {2282-2284}, abstract = {

We evaluated the potential antiviral effects of azithromycin on the nasopharyngeal virome of Nigerien children who had received multiple rounds of mass drug administration. We found that the respiratory burden of non-severe acute respiratory syndrome coronaviruses was decreased with azithromycin distributions. Clinical Trials Registration. NCT02047981.

}, keywords = {Administration, Oral, Antiviral Agents, Azithromycin, Child, Preschool, Coronavirus, Coronavirus Infections, Humans, Infant, Infant, Newborn, Mass Drug Administration, Nasopharynx, Nigeria, Viral Load}, issn = {1537-6591}, doi = {10.1093/cid/ciaa606}, author = {Doan, Thuy and Hinterwirth, Armin and Arzika, Ahmed M and Worden, Lee and Chen, Cindi and Zhong, Lina and Oldenburg, Catherine E and Keenan, Jeremy D and Lietman, Thomas M} } @article {151, title = {High-throughput sequencing of pooled samples to determine community-level microbiome diversity.}, journal = {Ann Epidemiol}, volume = {39}, year = {2019}, month = {2019 11}, pages = {63-68}, abstract = {

PURPOSE: Community-level interventions in cluster randomized controlled trials may alter the gut microbiome of individuals. The current method of estimating community diversities uses microbiome data obtained from multiple individual{\textquoteright}s specimens. Here we propose randomly pooling a number of microbiome samples from the same community into one sample before sequencing to estimate community-level microbiome diversity.

METHODS: We design and analyze an experiment to compare community microbiome diversity (gamma-diversity) estimates derived from 16S rRNA gene sequencing of 1) individually sequenced specimens vs. 2) pooled specimens collected from a community. Pool sizes of 10, 20, and 40 are considered. We then compare the gamma-estimates using Pearson{\textquoteright}s correlation as well as using Bland and Altman agreement analysis for three established diversity indices including richness, Simpson{\textquoteright}s and Shannon{\textquoteright}s.

RESULTS: The gamma-diversity estimates are highly correlated, with most being statistically significant. All correlations between all three diversity estimates are significant in the 10-pooled data. Pools comprising 40 specimens are closest to the line of agreement, but all pooled samples and individual samples fall within the 95\% limits of agreement.

CONCLUSIONS: Pooling microbiome samples before DNA amplification and metagenomics sequencing to estimate community-level diversity is a viable measure to consider in population-level association research studies.

}, keywords = {Administration, Oral, Anti-Bacterial Agents, Azithromycin, Bacteria, Biodiversity, Child, Preschool, Female, Gastrointestinal Microbiome, Gastrointestinal Tract, High-Throughput Nucleotide Sequencing, Humans, Infant, Infant, Newborn, Male, Metagenomics, Microbiota, Niger, Placebos, RNA, Ribosomal, 16S, Sequence Analysis, DNA}, issn = {1873-2585}, doi = {10.1016/j.annepidem.2019.09.002}, author = {Ray, Kathryn J and Cotter, Sun Y and Arzika, Ahmed M and Kim, Jessica and Boubacar, Nameywa and Zhou, Zhaoxia and Zhong, Lina and Porco, Travis C and Keenan, Jeremy D and Lietman, Thomas M and Doan, Thuy} } @article {196, title = {Indirect Effect of Azithromycin Use on the Intestinal Microbiome Diversity of Untreated Children: A Randomized Trial.}, journal = {Open Forum Infect Dis}, volume = {6}, year = {2019}, month = {2019 Mar}, pages = {ofz061}, abstract = {

Cohabiting children may share components of their intestinal microbiome. We evaluated whether receipt of azithromycin in one sibling confers changes to the intestinal microbiome in an untreated sibling compared with placebo in a randomized controlled trial. We found no evidence of an indirect effect of antibiotic use in cohabiting children. NCT03187834.

}, issn = {2328-8957}, doi = {10.1093/ofid/ofz061}, author = {Oldenburg, Catherine E and Sie, Ali and Coulibaly, Boubacar and Ouermi, Lucienne and Dah, Clarisse and Tapsoba, Charlemagne and B{\"a}rnighausen, Till and Lebas, Elodie and Arzika, Ahmed M and Cummings, Susie and Zhong, Lina and Lietman, Thomas M and Keenan, Jeremy D and Doan, Thuy} } @article {121, title = {Longer-Term Assessment of Azithromycin for Reducing Childhood Mortality in Africa.}, journal = {N Engl J Med}, volume = {380}, year = {2019}, month = {2019 Jun 06}, pages = {2207-2214}, abstract = {

BACKGROUND: The MORDOR I trial (Macrolides Oraux pour R{\'e}duire les D{\'e}c{\`e}s avec un Oeil sur la R{\'e}sistance) showed that in Niger, mass administration of azithromycin twice a year for 2 years resulted in 18\% lower postneonatal childhood mortality than administration of placebo. Whether this benefit could increase with each administration or wane owing to antibiotic resistance was unknown.

METHODS: In the Niger component of the MORDOR I trial, we randomly assigned 594 communities to four twice-yearly distributions of either azithromycin or placebo to children 1 to 59 months of age. In MORDOR II, all these communities received two additional open-label azithromycin distributions. All-cause mortality was assessed twice yearly by census workers who were unaware of participants{\textquoteright} original assignments.

RESULTS: In the MORDOR II trial, the mean ({\textpm}SD) azithromycin coverage was 91.3{\textpm}7.2\% in the communities that received twice-yearly azithromycin for the first time (i.e., had received placebo for 2 years in MORDOR I) and 92.0{\textpm}6.6\% in communities that received azithromycin for the third year (i.e., had received azithromycin for 2 years in MORDOR I). In MORDOR II, mortality was 24.0 per 1000 person-years (95\% confidence interval [CI], 22.1 to 26.3) in communities that had originally received placebo in the first year and 23.3 per 1000 person-years (95\% CI, 21.4 to 25.5) in those that had originally received azithromycin in the first year, with no significant difference between groups (P = 0.55). In communities that had originally received placebo, mortality decreased by 13.3\% (95\% CI, 5.8 to 20.2) when the communities received azithromycin (P = 0.007). In communities that had originally received azithromycin and continued receiving it for an additional year, the difference in mortality between the third year and the first 2 years was not significant (-3.6\%; 95\% CI, -12.3 to 4.5; P = 0.50).

CONCLUSIONS: We found no evidence that the effect of mass administration of azithromycin on childhood mortality in Niger waned in the third year of treatment. Childhood mortality decreased when communities that had originally received placebo received azithromycin. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number, NCT02047981.).

}, keywords = {Anti-Bacterial Agents, Azithromycin, Child Mortality, Child, Preschool, Drug Administration Schedule, Female, Humans, Infant, Infant Mortality, Male, Mass Drug Administration, Niger}, issn = {1533-4406}, doi = {10.1056/NEJMoa1817213}, author = {Keenan, Jeremy D and Arzika, Ahmed M and Maliki, Ramatou and Boubacar, Nameywa and Elh Adamou, Sanoussi and Moussa Ali, Maria and Cook, Catherine and Lebas, Elodie and Lin, Ying and Ray, Kathryn J and O{\textquoteright}Brien, Kieran S and Doan, Thuy and Oldenburg, Catherine E and Callahan, E Kelly and Emerson, Paul M and Porco, Travis C and Lietman, Thomas M} } @article {136, title = {Macrolide Resistance in MORDOR I - A Cluster-Randomized Trial in Niger.}, journal = {N Engl J Med}, volume = {380}, year = {2019}, month = {2019 Jun 06}, pages = {2271-2273}, keywords = {Administration, Oral, Anti-Bacterial Agents, Azithromycin, Child, Preschool, Drug Resistance, Bacterial, Humans, Infant, Macrolides, Niger, Pneumococcal Infections, Streptococcus pneumoniae}, issn = {1533-4406}, doi = {10.1056/NEJMc1901535}, author = {Doan, Thuy and Arzika, Ahmed M and Hinterwirth, Armin and Maliki, Ramatou and Zhong, Lina and Cummings, Susie and Sarkar, Samarpita and Chen, Cindi and Porco, Travis C and Keenan, Jeremy D and Lietman, Thomas M} } @article {56, title = {Azithromycin to Reduce Childhood Mortality in Sub-Saharan Africa.}, journal = {N Engl J Med}, volume = {378}, year = {2018}, month = {2018 Apr 26}, pages = {1583-1592}, abstract = {

BACKGROUND: We hypothesized that mass distribution of a broad-spectrum antibiotic agent to preschool children would reduce mortality in areas of sub-Saharan Africa that are currently far from meeting the Sustainable Development Goals of the United Nations.

METHODS: In this cluster-randomized trial, we assigned communities in Malawi, Niger, and Tanzania to four twice-yearly mass distributions of either oral azithromycin (approximately 20 mg per kilogram of body weight) or placebo. Children 1 to 59 months of age were identified in twice-yearly censuses and were offered participation in the trial. Vital status was determined at subsequent censuses. The primary outcome was aggregate all-cause mortality; country-specific rates were assessed in prespecified subgroup analyses.

RESULTS: A total of 1533 communities underwent randomization, 190,238 children were identified in the census at baseline, and 323,302 person-years were monitored. The mean ({\textpm}SD) azithromycin and placebo coverage over the four twice-yearly distributions was 90.4{\textpm}10.4\%. The overall annual mortality rate was 14.6 deaths per 1000 person-years in communities that received azithromycin (9.1 in Malawi, 22.5 in Niger, and 5.4 in Tanzania) and 16.5 deaths per 1000 person-years in communities that received placebo (9.6 in Malawi, 27.5 in Niger, and 5.5 in Tanzania). Mortality was 13.5\% lower overall (95\% confidence interval [CI], 6.7 to 19.8) in communities that received azithromycin than in communities that received placebo (P\<0.001); the rate was 5.7\% lower in Malawi (95\% CI, -9.7 to 18.9), 18.1\% lower in Niger (95\% CI, 10.0 to 25.5), and 3.4\% lower in Tanzania (95\% CI, -21.2 to 23.0). Children in the age group of 1 to 5 months had the greatest effect from azithromycin (24.9\% lower mortality than that with placebo; 95\% CI, 10.6 to 37.0). Serious adverse events occurring within a week after administration of the trial drug or placebo were uncommon, and the rate did not differ significantly between the groups. Evaluation of selection for antibiotic resistance is ongoing.

CONCLUSIONS: Among postneonatal, preschool children in sub-Saharan Africa, childhood mortality was lower in communities randomly assigned to mass distribution of azithromycin than in those assigned to placebo, with the largest effect seen in Niger. Any implementation of a policy of mass distribution would need to strongly consider the potential effect of such a strategy on antibiotic resistance. (Funded by the Bill and Melinda Gates Foundation; MORDOR ClinicalTrials.gov number, NCT02047981 .).

}, keywords = {Administration, Oral, Anti-Bacterial Agents, Azithromycin, Child Mortality, Child, Preschool, Communicable Disease Control, Communicable Diseases, Drug Resistance, Bacterial, Female, Humans, Infant, Infant Mortality, Malawi, Male, Mass Drug Administration, Niger, Public Health, Tanzania}, issn = {1533-4406}, doi = {10.1056/NEJMoa1715474}, author = {Keenan, Jeremy D and Bailey, Robin L and West, Sheila K and Arzika, Ahmed M and Hart, John and Weaver, Jerusha and Kalua, Khumbo and Mrango, Zakayo and Ray, Kathryn J and Cook, Catherine and Lebas, Elodie and O{\textquoteright}Brien, Kieran S and Emerson, Paul M and Porco, Travis C and Lietman, Thomas M} } @article {221, title = {Mass Azithromycin Distribution and Community Microbiome: A Cluster-Randomized Trial.}, journal = {Open Forum Infect Dis}, volume = {5}, year = {2018}, month = {2018 Aug}, pages = {ofy182}, abstract = {

Background: Mass distributions of oral azithromycin have long been used to eliminate trachoma, and they are now being proposed to reduce childhood mortality. The observed benefit appears to be augmented with each additional treatment, suggesting a possible community-level effect. Here, we assess whether 2 biannual mass treatments of preschool children affect the community{\textquoteright}s gut microbiome at 6 months after the last distribution.

Methods: In this cluster-randomized controlled trial, children aged 1-60 months in the Dossa region of Niger were randomized at the village level to receive a single dose of azithromycin or placebo every 6 months. Fecal samples were collected 6 months after the second treatment for metagenomic deep sequencing. The prespecified primary outcome was the Euclidean PERMANOVA of the gut microbiome, or effectively the distance between the genus-level centroid at the community level, with the secondary outcome being the Simpson{\textquoteright}s α diversity.

Results: In the azithromycin arm, the gut microbial structures were significantly different than in the placebo arm (Euclidean PERMANOVA, \< .001). Further, the diversity of the gut microbiome in the azithromycin arm was significantly lower than in the placebo arm (inverse Simpson{\textquoteright}s index, = .005).

Conclusions: Two mass azithromycin administrations, 6 months apart, in preschool children led to long-term alterations of the gut microbiome structure and community diversity. Here, long-term microbial alterations in the community did not imply disease but were associated with an improvement in childhood mortality.

Clinical Trials Registration: NCT02048007.

}, issn = {2328-8957}, doi = {10.1093/ofid/ofy182}, author = {Doan, Thuy and Hinterwirth, Armin and Arzika, Ahmed M and Cotter, Sun Y and Ray, Kathryn J and O{\textquoteright}Brien, Kieran S and Zhong, Lina and Chow, Eric D and Zhou, Zhaoxia and Cummings, Susie L and Fry, Dionna and Oldenburg, Catherine E and Worden, Lee and Porco, Travis C and Keenan, Jeremy D and Lietman, Thomas M} } @article {276, title = {Gut Microbial Diversity in Antibiotic-Naive Children After Systemic Antibiotic Exposure: A Randomized Controlled Trial.}, journal = {Clin Infect Dis}, volume = {64}, year = {2017}, month = {2017 05 01}, pages = {1147-1153}, abstract = {

Background: Antibiotic exposure can alter the gut microbiome. We evaluate the effects of azithromycin on the gut microbiome diversity of children from an antibiotic-naive community in Niger.

Methods: A population-based sample of 80 children aged 1-60 months in the Dosso region of Niger was randomized to receive a single dose of either oral azithromycin or placebo. Fecal samples were collected immediately before treatment and 5 days after treatment for 16S rRNA gene sequencing. The prespecified outcome was α-diversity (inverse Simpson{\textquoteright}s α-diversity index), with secondary outcomes of β and γ Simpson{\textquoteright}s and Shannon{\textquoteright}s diversities.

Results: At 5 days after treatment, 40 children aged 1-60 months were analyzed in the azithromycin-treated group and 40 children in the placebo-treated group. Diversity of the gut microbiome was significantly lower in the treated group (inverse Simpson{\textquoteright}s α-diversity, 5.03; 95\% confidence interval [CI], 4.08-6.14) than in the placebo group (6.91; 95\% CI, 5.82-8.21; P = .03). Similarly, the Shannon{\textquoteright}s α-diversity was lower in the treated group (10.60; 95\% CI, 8.82-12.36) than the placebo group (15.42; 95\% CI, 13.24-17.80; P = .004). Simpson{\textquoteright}s community-level (γ) diversity decreased with azithromycin exposure from 17.72 (95\% CI, 13.80-20.21) to 10.10 (95\% CI, 7.80-11.40; P = .00008), although β-diversity was not significantly reduced (2.56, 95\% CI, 1.88-3.12; to 2.01, 95\% CI, 1.46-2.51; P = .26).

Conclusions: Oral administration of azithromycin definitively decreases the diversity of the gut microbiome of children in an antibiotic-naive community.

Clinical Trials Registration: NCT02048007.

}, keywords = {Administration, Oral, Anti-Bacterial Agents, Azithromycin, Bacteria, Biodiversity, Child, Preschool, Cluster Analysis, DNA, Ribosomal, Female, Gastrointestinal Microbiome, Gastrointestinal Tract, Humans, Infant, Male, Niger, Phylogeny, Placebos, RNA, Ribosomal, 16S, Sequence Analysis, DNA}, issn = {1537-6591}, doi = {10.1093/cid/cix141}, author = {Doan, Thuy and Arzika, Ahmed M and Ray, Kathryn J and Cotter, Sun Y and Kim, Jessica and Maliki, Ramatou and Zhong, Lina and Zhou, Zhaoxia and Porco, Travis C and Vanderschelden, Benjamin and Keenan, Jeremy D and Lietman, Thomas M} }