Transcription shifts in gut bacteria shared between mothers and their infants.

The infant gut microbiome contains a portion of bacteria that originate from the maternal gut. In the infant gut these bacteria encounter a new metabolic environment that differs from the adult gut, consequently requiring adjustments in their activities. We used pilot community RNA sequencing data (metatranscriptomes) from ten mother-infant dyads participating in the NiPPeR Study to characterize bacterial gene expression shifts following mother-to-infant transmission. Maternally-derived bacterial strains exhibited large scale gene expression shifts following the transmission to the infant gut, with 12,564 activated and 14,844 deactivated gene families. The implicated genes were most numerous and the magnitude shifts greatest in Bacteroides spp. This pilot study demonstrates environment-dependent, strain-specific shifts in gut bacteria function and underscores the importance of metatranscriptomic analysis in microbiome studies.

Does the maternal vaginal microbiota play a role in seeding the microbiota of neonatal gut and nose?

The acquisition and early maturation of infant microbiota is not well understood despite its likely influence on later health. We investigated the contribution of the maternal microbiota to the microbiota of infant gut and nose in the context of mode of delivery and feeding. Using 16S rRNA sequencing and specific qPCR, we profiled microbiota of 42 mother-infant pairs from the GUSTO birth cohort, at body sites including maternal vagina, rectum and skin; and infant stool and nose. In our study, overlap between maternal vaginal microbiota and infant faecal microbiota was minimal, while the similarity between maternal rectal microbiota and infant microbiota was more pronounced. However, an infant's nasal and gut microbiota were no more similar to that of its own mother, than to that of unrelated mothers. These findings were independent of delivery mode. We conclude that the transfer of maternal vaginal microbes play a minor role in seeding infant stool microbiota. Transfer of maternal rectal microbiota could play a larger role in seeding infant stool microbiota, but approaches other than the generally used analyses of community similarity measures are likely to be needed to quantify bacterial transmission. We confirmed the clear difference between microbiota of infants born by Caesarean section compared to vaginally delivered infants and the impact of feeding mode on infant gut microbiota. Only vaginally delivered, fully breastfed infants had gut microbiota dominated by Bifidobacteria. Our data suggest that reduced transfer of maternal vaginal microbial is not the main mechanism underlying the differential infant microbiota composition associated with Caesarean delivery. The sources of a large proportion of infant microbiota could not be identified in maternal microbiota, and the sources of seeding of infant gut and nasal microbiota remain to be elucidated.

High prevalence of colonization of oral cavity by respiratory pathogens in frail older patients with oropharyngeal dysphagia.

BACKGROUND: Aspiration pneumonia (AP) is caused by dysfunctional swallowing resulting in aspiration of material colonized by respiratory pathogens. The aim of this study was to assess and compare the swallowing physiology, health status, oral health status, and oral/nasal microbiota in frail older patients (FOP) with oropharyngeal dysphagia (OD) and a control group. METHODS: We studied 47 FOP (>70 year) with OD by videofluoroscopy (17 with acute pneumonia -APN-, 15 with prior pneumonia-PNP- and 15 without) and 14 older controls without OD (H). Oral/nasal colonization by five respiratory pathogens was evaluated by qPCR, whereas commensal microbiota composition was assessed by pyrosequencing. KEY RESULTS: (i) Frail older patients with OD presented similar comorbidities, poor functionality, polymedication, and prevalent videofluoroscopic signs of impaired safety of swallow (33.3-61.5%). However, patients with OD-APN also presented malnutrition, delayed laryngeal vestibule closure (409.23 ± 115.6 ms; p < 0.05), and silent aspirations (15.6%). (ii) Oral health was poor in all groups, 90% presented periodontitis and 72%, caries. (iii) Total bacterial load was similar in all groups, but higher in the oropharynx (>10(8) CFU/mL) than in the nose (<10(6) CFU/mL) (p < 0.0001). Colonization by respiratory pathogens was very high: 93% in OD patients (p < 0.05 vs H); 93% in OD-PNP (p < 0.05 vs H); 88% in OD-APN (p = 0.07 vs H), and lower in controls (67%). CONCLUSIONS & INFERENCES: Frail older patients with OD had impaired health status, poor oral health, high oral bacterial load, and prevalence of oral colonization by respiratory pathogens and VFS signs of impaired safety of swallow, and were therefore at risk for contracting AP.