Opportunities to assess factors contributing to the development of the intestinal microbiota in infants living in developing countries

The impact of mass drug administration of antibiotics on the gut microbiota of target populations

Antibiotics have become a mainstay of healthcare in the past century due to their activity against pathogens. This manuscript reviews the impact of antibiotic use on the intestinal microbiota in the context of mass drug administration (MDA). The importance of the gut microbiota to human metabolism and physiology is now well established, and antibiotic exposure may impact host health via collateral effects on the microbiota and its functions. To gain further insight into how gut microbiota respond to antibiotic perturbation and the implications for public health, factors that influence the impact of antibiotic exposure on the microbiota, potential health outcomes of antibiotic-induced microbiota alterations, and strategies that have the potential to ameliorate these wider antibiotic-associated microbiota perturbations are also reviewed.

Growth from Birth Through Six Months for Infants of Mothers in the "Women First" Preconception Maternal Nutrition Trial

OBJECTIVE

To evaluate whether the fetal linear growth effects of maternal nutrition supplementation would be maintained through 6 months postnatal age.

STUDY DESIGN

The Women First trial was a multicountry, individually randomized clinical trial that compared the impact of maternal nutrition supplementation initiated preconception (Arm 1) vs at ∼11 weeks of gestation (Arm 2), vs no supplement (Arm 3); the intervention was discontinued at delivery. Trial sites were in Democratic Republic of Congo, Guatemala, India, and Pakistan. Analysis includes 2421 infants born to 2408 randomized women. Primary outcome was the trajectory of length-for-age z scores (LAZ) by arm, based on assessments at birth and 1, 3, and 6 months. We fitted longitudinal models on growth from birth to 6 months using generalized estimating equations; maternal intervention effects were evaluated, adjusting for site and baseline maternal covariates.

RESULTS

Linear growth for Arms 1 and 2 was statistically greater than for Arm 3 in 3 of the 4 countries, with average pairwise mean differences in LAZ of 0.25 (95% CI 0.15-0.35; P < .001) and 0.19 (95% CI 0.09-0.28; P < .001), respectively. Compared with Arm 3, average overall adjusted relative risks (95% CI) for stunting (LAZ <-2) were lower for Arms 1 and 2: 0.76 (0.66-0.87; P < .001) and 0.77 (0.67-0.88; P < .001), respectively.

CONCLUSIONS

Improved linear growth in early infancy observed for the 2 intervention arms supports the critical importance of maternal nutrition before conception and in the early phase of gestation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01883193.

Peanut butter-based formulations of amoxicillin for pediatric applications

BACKGROUND

Child mortality is a major global health challenge, especially in regions of limited resources. Accessibility to lifesaving medicine and adequate nutrition is essential to reduce child mortality and improve the health and well-being of the world's most vulnerable children.

METHODS

We have developed NutMox, a novel pediatric formulation of the β-lactam antibiotic amoxicillin in a matrix of peanut-based ready-to-use therapeutic food (RUTF) consisting of peanut butter, sugar, vegetable oil, dry milk and vitamins. NutMox is ready to use and thermostable, requires no chewing or pill swallowing and provides both an antibiotic and nutrition.

RESULTS

Amoxicillin in NutMox formulations was stable for at least 12 months at storage temperatures of 4°C, 25°C and 37°C. Amoxicillin formulated in NutMox displayed similar pharmacokinetics in mice to that in suspension.

CONCLUSIONS

Our results demonstrated the feasibility of a peanut butter-based matrix for pediatric formulations of amoxicillin, suggesting that such a matrix can serve as a base for delivering medications in addition to its current use as an RUTF.

Long-term in vitro Culture of Cryptosporidium parvum

Continuous in vitro growth of Cryptosporidium parvum has proved difficult and conventional in vitro culture techniques result in short-term (2-5 days) growth of the parasite resulting in thin-walled oocysts that fail to propagate using in vitro cultures, and do not produce an active infection using immunosuppressed or immunodeficient mouse models (Arrowood, 2002). Here we describe the use of hollow fiber bioreactors (HFB) that simulate in vivo conditions by providing oxygen and nutrients to host intestinal cells from the basal surface and permit the establishment of a low redox, high nutrient environment on the apical surface. When inoculated with 10⁵ C. parvum (Iowa isolate) oocysts the bioreactor produced 10⁸ oocysts per ml (20 ml extra-capillary volume) after 14 days, and was maintained for over 2 years. In vivo infectivity studies using a TCR-α-immune deficient mouse model showed that oocysts produced from the bioreactor at 6, 12 and 18 months were indistinguishable from the parent Iowa isolate used to initiate the culture. HFB produced oocysts had similar percent excystation profiles to the parent Iowa isolate.

Challenges to Sustainable Safe Drinking Water: A Case Study of Water Quality and Use across Seasons in Rural Communities in Limpopo Province, South Africa

Consumption of microbial-contaminated water can result in diarrheal illnesses and enteropathy with the heaviest impact upon children below the age of five. We aimed to provide a comprehensive analysis of water quality in a low-resource setting in Limpopo province, South Africa. Surveys were conducted in 405 households in rural communities of Limpopo province to determine their water-use practices, perceptions of water quality, and household water-treatment methods. Drinking water samples were tested from households for microbiological contamination. Water from potential natural sources were tested for physicochemical and microbiological quality in the dry and wet seasons. Most households had their primary water source piped into their yard or used an intermittent public tap. Approximately one third of caregivers perceived that they could get sick from drinking water. All natural water sources tested positive for fecal contamination at some point during each season. The treated municipal supply never tested positive for fecal contamination; however, the treated system does not reach all residents in the valley; furthermore, frequent shutdowns of the treatment systems and intermittent distribution make the treated water unreliable. The increased water quantity in the wet season correlates with increased treated water from municipal taps and a decrease in the average contaminant levels in household water. This research suggests that wet season increases in water quantity result in more treated water in the region and that is reflected in residents' water-use practices.

The global problem of childhood diarrhoeal diseases: emerging strategies in prevention and management

Acute diarrhoeal diseases remain a leading cause of global morbidity and mortality particularly among young children in resource-limited countries. Recent large studies utilizing case-control design, prospective sampling and more sensitive and broad diagnostic techniques have shed light on particular pathogens of importance and highlighted the previously under recognized impact of these infections on post-acute illness mortality and growth. Vaccination, particularly against rotavirus, has emerged as a key effective means of preventing significant morbidity and mortality from childhood diarrhoeal disease. Other candidate vaccines against leading diarrhoeal pathogens, such as enterotoxigenic Escherichia coli and Shigella spp., also hold significant promise in further ameliorating the burden of enteric infections in children. Large studies are also currently underway evaluating novel and potential easy-to-implement water, sanitation and hygiene (WASH) preventive strategies. Given the ongoing global burden of this illness, the paucity of new advances in case management over the last several decades remains a challenge. The increasing recognition of post-acute illness mortality and growth impairment has highlighted the need for interventions that go beyond management of dehydration and electrolyte disturbances. The few trials of novel promising interventions such as probiotics have mainly been conducted in high-income settings. Trials of antimicrobials have also been primarily conducted in high-income settings or in travellers from high-income settings. Bloody diarrhoea has been shown to be a poor marker of potentially treatable bacterial enteritis, and rising antimicrobial resistance has also made empiric antimicrobial therapy more challenging in many settings. Novel effective and sustainable interventions and diagnostic strategies are clearly needed to help improve case management. Diarrhoeal disease and other enteric infections remain an unmet challenge in global child health. Most promising recent developments have been focused around preventive measures, in particular vaccination. Further advances in prevention and case management including the possible use of targeted antimicrobial treatment are also required to fully address this critical burden on child health and human potential.

The Burden of Enteropathy and "Subclinical" Infections

Environmental enteropathy is a chronic condition of the small intestine associated with increased intestinal permeability, mucosal inflammation, malabsorption, and systemic inflammation. It is commonly accompanied by enteric infections and is misleadingly considered a subclinical disease. Potential effects of enteric infections and enteropathy on vaccine responses, child growth, cognitive development, and even later life obesity, diabetes, and metabolic syndrome are increasingly being recognized. Herein, we review the evolving challenges to defining environmental enteropathy and enteric infections, current evidence for the magnitude and determinants of its burden, new assessment tools, and relevant interventions.

Perspective: What Makes It So Difficult to Mitigate Worldwide Anemia Prevalence?

Anemia can be related to decreased production or increased loss of erythrocytes, or both, leading to many underlying and often overlapping causes. A largely cereal-based diet with plenty of phytates, polyphenols, and other ligands that inhibit intestinal iron absorption predominated in preindustrial Europe and predominates in present-day developing countries alike. In both situations, we find poor hygienic conditions, which frequently lead to anemia of inflammation. The large number of possible causes and their interaction shows why it is so difficult to mitigate anemia prevalence. Diagnostic biomarkers are required to differentiate the different types of anemia and to treat them appropriately. Some of them are well established in adults [e.g., concentrations of serum ferritin, soluble transferrin receptor (sTfR), and serum iron or the ratio of sTfR to log ferritin]. Others, such as serum hepcidin, hold considerable promise, although they are not yet widely used. A particular issue is to establish reference values for biomarkers in infants and children at different ages. The fact that resource-rich postindustrial societies have a very low prevalence of iron-deficiency anemia offers hope that common types of anemia can be eliminated. In contrast, inborn forms of anemia, such as thalassemia, and anemias related to underlying diseases (e.g., bleeding tumors or peptic ulcers, gynecologic blood losses, or renal diseases) require an operational health system to be addressed appropriately.

Characterization of Gastric Microbiota in Twins

Contribution of host genetic backgrounds in the development of gastric microbiota has not been clearly defined. This study was aimed to characterize the biodiversity, structure and composition of gastric microbiota among twins. A total of four pairs of twins and eight unrelated individuals were enrolled in the study. Antral biopsies were obtained during endoscopy. The bacterial 16S rRNA gene was amplified and pyrosequenced. Sequences were analyzed for the composition, structure, and α and β diversities of gastric microbiota. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Fusobacteria were the most predominant phyla of gastric microbiota. Each individual, twins as well as unrelated individuals, harbored a microbiota of distinct composition. There was no evidence of additional similarity in the richness and evenness of gastric microbiota among co-twins as compared to unrelated individuals. Calculations of θ_YC and PCoA demonstrated that the structure similarity of gastric microbial community between co-twins did not increase compared to unrelated individuals. In contrast, the structure of microbiota was altered enormously by Helicobacter pylori infection. These results suggest that host genetic backgrounds had little effect in shaping the gastric microbiota. This property of gastric microbiota could facilitate the studies discerning the role of microbiota from genetic grounds in the pathogenesis.

The Significance of the Enteric Microbiome on the Development of Childhood Disease: A Review of Prebiotic and Probiotic Therapies in Disorders of Childhood

Recent studies have highlighted the fact that the enteric microbiome, the trillions of microbes that inhabit the human digestive tract, has a significant effect on health and disease. Methods for manipulating the enteric microbiome, particularly through probiotics and microbial ecosystem transplantation, have undergone some study in clinical trials. We review some of the evidence for microbiome alteration in relation to childhood disease and discuss the clinical trials that have examined the manipulation of the microbiome in an effort to prevent or treat childhood disease with a primary focus on probiotics, prebiotics, and/or synbiotics (ie, probiotics + prebiotics). Studies show that alterations in the microbiome may be a consequence of events occurring during infancy and/or childhood such as prematurity, C-sections, and nosocomial infections. In addition, certain childhood diseases have been associated with microbiome alterations, namely necrotizing enterocolitis, infantile colic, asthma, atopic disease, gastrointestinal disease, diabetes, malnutrition, mood/anxiety disorders, and autism spectrum disorders. Treatment studies suggest that probiotics are potentially protective against the development of some of these diseases. Timing and duration of treatment, the optimal probiotic strain(s), and factors that may alter the composition and function of the microbiome are still in need of further research. Other treatments such as prebiotics, fecal microbial transplantation, and antibiotics have limited evidence. Future translational work, in vitro models, long-term and follow-up studies, and guidelines for the composition and viability of probiotic and microbial therapies need to be developed. Overall, there is promising evidence that manipulating the microbiome with probiotics early in life can help prevent or reduce the severity of some childhood diseases, but further research is needed to elucidate biological mechanisms and determine optimal treatments.

Assessing the Intestinal Microbiota in the SHINE Trial

Advances in DNA sequencing technology now allow us to explore the dynamics and functions of the microbes that inhabit the human body, the microbiota. Recent studies involving experimental animal models suggest a role of the gut microbiota in growth. However, the specific changes in the human gut microbiota that contribute to growth remain unclear, and studies investigating the gut microbiota as a determinant of environmental enteric dysfunction (EED) and child stunting are lacking. In this article, we review the evidence for a link between the developing infant gut microbiota, infant feeding, EED, and stunting, and discuss the potential causal pathways relating these variables. We outline the analytic approaches we will use to investigate these relationships, by capitalizing on the longitudinal design and randomized interventions of the Sanitation Hygiene Infant Nutrition Efficacy trial in Zimbabwe.

Tropical and travel-associated norovirus: current concepts

PURPOSE OF REVIEW

We highlight recent advances relevant to understanding norovirus infections in the tropics, both in populations living in developing settings and travelers to these regions.

RECENT FINDINGS

Because of the decrease in diarrheal disease associated with the global rollout of vaccines against rotavirus, norovirus is emerging as the predominant cause of diarrhea morbidity among children in the tropics, and evidence suggests that it contributes to adult disease in endemic populations and travelers. In addition to identifying potential target populations for preventive measures, we provide an update on norovirus vaccine development and concepts related to their implementation in low-income and middle-income countries.

SUMMARY

These current concepts related to norovirus-attributable disease burden, clinical significance, and economic impact can potentially be applied to tailoring efforts to prevent and mitigate the effects of this important enteropathogen.

Gut Microbiota: A Modulator of Brain Plasticity and Cognitive Function in Ageing

Gut microbiota have recently been a topic of great interest in the field of microbiology, particularly their role in normal physiology and its influence on human health in disease. A large body of research has supported the presence of a pathway of communication between the gut and the brain, modulated by gut microbiota, giving rise to the term “microbiota-gut-brain” axis. It is now thought that, through this pathway, microbiota can affect behaviour and modulate brain plasticity and cognitive function in ageing. This review summarizes the evidence supporting the existence of such a connection and possible mechanisms of action whereby microbiota can influence the function of the central nervous system. Since normalisation of gut flora has been shown to prevent changes in behaviour, we further postulate on possible therapeutic targets to intervene with cognitive decline in ageing. The research poses various limitations, for example uncertainty about how this data translates to broad human populations. Nonetheless, the microbiota-gut-brain axis is an exciting field worthy of further investigation, particularly with regards to its implications on the ageing population.