Gut Bacterial Families Are Associated with Body Composition and Metabolic Risk Markers in School-Aged Children in Rural Mexico

Background: Differences in gut microbiota composition have been associated with obesity and metabolic alterations in children. The aim of this study was to analyze the abundance of the main bacterial families of the gut among children according to their body composition and metabolic markers. Methods: A cross-sectional study was conducted with 93 school-aged children (8.4 ± 1.6 years old). Anthropometric and body composition variables were measured and a blood sample was collected to determine glucose, insulin, lipid profile, C-reactive protein, leptin, and cytokines [interleukin 6, interleukin 10 (IL-10), tumor necrosis factor α (TNFα)]. DNA was extracted from stool samples and the abundance of bacterial families (Bacteroidaceae-Porphyromonadaceae-Prevotellaceae, Lactobacillaceae, Enterococcaceae, and Lachnospiraceae-Ruminococcaceae) was determined by qPCR assays. Results: Children with obesity and high waist/height ratio had lower Bacteroidaceae-Porphyromonadaceae-Prevotellaceae and higher abundance of Lactobacillaceae when compared with normal-weight children. TNFα was negatively associated and IL-10 was positively associated with Bacteroidaceae-Porphyromonadaceae-Prevotellaceae. Triglycerides showed a positive relationship with Lachnospiraceae-Ruminococcaceae whereas high-density lipoprotein-cholesterol was negatively associated with Lactobacillaceae. Conclusion: In rural Mexican school-aged children, a low abundance of Bacteroidaceae-Porphyromonadaceae-Prevotellaceae and a high abundance of Lactobacillaceae are associated with obesity and metabolic disturbances.

Age-Dependent Dissimilarity of the Nasopharyngeal and Middle Ear Microbiota in Children With Acute Otitis Media

Acute bacterial otitis media is usually caused by otopathogens ascending to the middle ear from the nasopharynx (NP). However, it is unknown if the nasopharyngeal microbiota of children with acute otitis media (AOM) can serve as an age-dependent or independent proxy for the microbial communities of the middle ear fluid (MEF) as there is a lack of 16S rRNA amplicon sequencing studies simultaneously analyzing the microbial communities of the two sites. Within this study, we performed 16S rRNA next generation sequencing on a total of 286 nasopharyngeal swabs (NPSs) collected between 2004 and 2013 within a Swiss national AOM surveillance program from children (0-6 years) with AOM. In addition, 42/286 children had spontaneous tympanic membrane perforation and, therefore, those MEF could also be analyzed. We found that alpha [Richness, Shannon diversity index (SDI) and Evenness] and beta diversity measurements of the nasopharyngeal bacterial microbiota showed a clear dependency of the increasing age of the children. In more detail, bacterial richness and personalized profiles (measured by beta dispersion) were higher and more frequent in older children, respectively. Dissimilarity values based on the binary distance matrix of the microbiota patterns of the NP and the MEF also correlated with increasing age. In general, positive (PPV) and negative predictive values (NPV) of the most abundant operational taxonomic units (OTUs) in the NP were moderately and well predictive for their presence in the MEF, respectively. This data is crucial to better understand polymicrobial infections and therefore AOM pathogenesis.

Dynamics of the nasal microbiota in infancy: a prospective cohort study

BACKGROUND

Understanding the composition and dynamics of the upper respiratory tract microbiota in healthy infants is a prerequisite to investigate the role of the microbiota in patients with respiratory diseases. This is especially true in early life, when the immune system is in development.

OBJECTIVE

We sought to describe the dynamics of the upper respiratory tract microbiota in healthy infants within the first year of life.

METHODS

After exclusion of low-quality samples, microbiota characterization was performed by using 16S rDNA pyrosequencing of 872 nasal swabs collected biweekly from 47 unselected infants.

RESULTS

Bacterial density increased and diversity decreased within the first year of life (R(2) = 0.95 and 0.73, respectively). A distinct profile for the first 3 months of life was found with increased relative abundances of Staphlyococcaceae and Corynebacteriaceae (exponential decay: R(2) = 0.94 and 0.96, respectively). In addition, relative bacterial abundance and composition differed significantly from summer to winter months. The individual composition of the microbiota changed with increasing time intervals between samples and was best modeled by an exponential function (R(2) = 0.97). Within-subject dissimilarity in a 2-week time interval was consistently lower than that between subjects, indicating a personalized microbiota.

CONCLUSION

This study reveals age and seasonality as major factors driving the composition of the nasal microbiota within the first year of life. A subject's microbiota is personalized but dynamic throughout the first year. These data are indispensable to interpretation of cross-sectional studies and investigation of the role of the microbiota in both healthy subjects and patients with respiratory diseases. They might also serve as a baseline for future intervention studies.