We found that the relatively simple microbiota of young infants shifts predictably to a more mature anaerobic microbiota during infancy and the dynamics of this shift are influenced by environmental factors. In this longitudinal study of 75 infants, we demonstrate high interindividual variability within the normal range of birth outcomes, especially in the rate of microbiota progression. Most had acquired a microbiota profile high in Bifidobacterium and Collinsella by 6 months of age, but the time point of this acquisition was later in infants delivered by caesarean section and those born after a shorter duration of gestation. Independently of the delivery mode and gestation duration, infants who acquired a profile high in Bifidobacterium and Collinsella at a later age had lower adiposity at 18 months of age.

Staphylococcus aureus is a major agent of bovine mastitis. The concomitant emergence of pig-associated methicillin-resistant S. aureus (MRSA) in human carriage and infection requires a reexamination of the host range and specificity of human-and cow-associated S. aureus strains, something which has not been systematically studied previously. The genetic relatedness of 500 S. aureus isolates from bovine mastitis cases, 57 isolates from nasal carriage of farmers, and 133 isolates from nonfarmers was determined by amplified fragment length polymorphism (AFLP) analysis and spa typing. Multilocus sequence typing (MLST) was conducted on a subset of isolates to match AFLP clusters with MLST clonal complexes (CCs). This data set allowed us to study host range and host specificity and to estimate the extent of bovine-tohuman transmission. The genotype compositions of S. aureus isolates from farmers and nonfarmers were very similar, while the mastitis isolates were quite distinct. Overall, transmission was low, but specific genotypes did show increased cow-to-human transmission. Unexpectedly, more than one-third of mastitis isolates belonged to CC8, a lineage which has not been considered to be bovine mastitis associated, but it is well known from human carriage and infection (i.e., USA300). Despite the fact that we did detect some transmission of other genotypes from cows to farmers, no transmission of CC8 isolates to farmers was detected, except for one tentative case. This was despite the close genetic relatedness of mastitis CC8 strains to nonfarmer carriage strains. These results suggest that the emergence of the new bovine-adapted genotype was due to a recent host shift from humans to cows concurrent with a loss of the ability to colonize humans. More broadly, our results indicate that host specificity is a lineage-specific trait that can rapidly evolve.The main niche and the largest reservoir of Staphylococcus aureus are human nares. On average, every third person is colonized with this facultative pathogen, making ca. 2 billion people colonized worldwide. Despite the fact that only a very small fraction of the carriers ever develop staphylococcal disease, its global burden is remarkable (27). Steadily increasing rates of colonization and infections with methicillin-resistant S. aureus (MRSA) are of special concern (20) because of the limited therapeutic options for such infections.Because of their sheer population size, farm animals constitute a potentially enormous reservoir of any pathogen. Even though the largest reservoir of S. aureus is human nares, the second largest may well be cows. The prevalence of S. aureus in bovine mastitis was estimated to be 3 to 5% (28, 34). Given the world's milking cow population of 1.5 billion (31), up to 75 million cows can be infected worldwide. The widespread colonization of pigs with a specific lineage of MRSA, ST398 (2), and emerging infections in humans (10,22,32) showed that the animal reservoir of. S. aureus can have potentially serious consequences for human health care...

The microbiota of breast milk from Chinese lactating mothers at different stages of lactation was examined in the framework of a Maternal Infant Nutrition Growth (MING) study investigating the dietary habits and breast milk composition in Chinese urban mothers. We used microbiota profiling based on the sequencing of fragments of 16S rRNA gene and specific qPCR for bifidobacteria, lactobacilli and total bacteria to study microbiota of the entire breast milk collected using standard protocol without aseptic cleansing (n = 60), and the microbiota of the milk collected aseptically (n = 30). We have also investigated the impact of the delivery mode and the stage of lactation on the microbiota composition. The microbiota of breast milk was dominated by streptococci and staphylococci for both collection protocols and, in the case of standard collection protocol, Acinetobacter sp. While the predominance of streptococci and staphylococci was consistently reported previously for other populations, the abundance of Acinetobacter sp. was reported only once before in a study where milk collection was done without aseptic cleansing of the breast and rejection of foremilk. Higher bacterial counts were found in the milk collected using standard protocol. Bifidobacteria and lactobacilli were present in few samples with low abundance. We observed no effect of the stage of lactation or the delivery mode on microbiota composition. Methodological and geographical differences likely explain the variability in microbiota composition reported to date.

(2015) Rate of establishing the gut microbiota in infancy has consequences for future health, Gut Microbes, 6:5, 321-325,

The genetic determinants and phenotypic traits which make a Staphylococcus aureus strain a successful colonizer are largely unknown. The genetic diversity and population structure of 133 S. aureus isolates from healthy, generally risk-free adult carriers were investigated using four different typing methods: multilocus sequence typing (MLST), amplified fragment length polymorphism analysis (AFLP), double-locus sequence typing (DLST), and spa typing were compared. Carriage isolates displayed great genetic diversity which could only be revealed fully by DLST. Results of AFLP and MLST were highly concordant in the delineation of genotypic clusters of closely related isolates, roughly equivalent to clonal complexes. spa typing and DLST provided considerably less phylogenetic information. The resolution of spa typing was similar to that of AFLP and inferior to that of DLST. AFLP proved to be the most universal method, combining a phylogeny-building capacity similar to that of MLST with a much higher resolution. However, it had a lower reproducibility than sequencing-based MLST, DLST, and spa typing. We found two cases of methicillin-resistant S. aureus colonization, both of which were most likely associated with employment at a health service. Of 21 genotypic clusters detected, 2 were most prevalent: cluster 45 and cluster 30 each colonized 24% of the carrier population. The number of bacteria found in nasal samples varied significantly among the clusters, but the most prevalent clusters were not particularly numerous in the nasal samples. We did not find much evidence that genotypic clusters were associated with different carrier characteristics, such as age, sex, medical conditions, or antibiotic use. This may provide empirical support for the idea that genetic clusters in bacteria are maintained in the absence of adaptation to different niches. Alternatively, carrier characteristics other than those evaluated here or factors other than human hosts may exert selective pressure maintaining genotypic clusters.

bOur study is the first to compare the nasopharyngeal microbiota of pediatric pneumonia patients and control children by 454 pyrosequencing. A distinct microbiota was associated with different pneumonia etiologies. Viral pneumonia was associated with a high abundance of the operational taxonomic unit (OTU) corresponding to Moraxella lacunata. Patients with nonviral pneumonia showed high abundances of OTUs of three typical bacterial pathogens, Streptococcus pneumoniae complex, Haemophilus influenzae complex, and Moraxella catarrhalis. Patients classified as having no definitive etiology harbored microbiota particularly enriched in the H. influenzae complex. We did not observe a commensal taxon specifically associated with health. The microbiota of the healthy nasopharynx was more diverse and contained a wider range of less abundant taxa. P neumonia is the leading cause of childhood mortality worldwide, claiming 2 million lives yearly among young children (1). The etiology of pediatric pneumonia is complex and not routinely determined in clinical practice (2). Its definitive determination remains challenging (3). Clinical research shows that Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus are the leading pathogens of bacterial pneumonia (1, 4). Respiratory syncytial virus (RSV), parainfluenza, and influenza viruses are the main causes of pediatric viral pneumonia (e.g., see references 5 and 6). S. pneumoniae and H. influenzae frequently colonize the nasopharynx of young children, and the nasopharyngeal (NP) carriage of S. pneumoniae is considered key to pneumonia and other pneumococcal diseases (7). However, the mere nasopharyngeal presence of bacterial pathogens does not necessarily lead to invasive lung infection. Various mechanisms, such as competition with resident nonpathogenic microbiota, viral coinfection, or host immune factors are likely to affect the transition from nasopharyngeal colonization to pneumonia (8). The increasing accessibility of culture-independent sequencing methods has permitted microbiota description at various body sites (9), and the potential of commensal microbiota to modify the disease process is receiving increasing attention (10).Previous culture-independent studies of the nasopharyngeal microbiota of young children looked at healthy children (11) and compared the microbiota composition of healthy children and children with acute otitis media (12). In the present study, we analyzed the nasopharyngeal microbiota composition, including the presence of respiratory viruses, in pediatric pneumonia patients and matched healthy controls and looked for microbiota associations with the disease status. MATERIALS AND METHODS Patients and clinical samples.A prospective case-control study conducted in 2008 to 2009 in 3 major hospitals in Switzerland (Geneva, Lausanne, and Sion) to investigate pediatric community-acquired pneumonia etiology was described in detail elsewhere (13). Briefly, pneumonia cases were diagnosed according to the WHO criteria (14) in children 2 ...

bCarriage of animal-associated methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 398 (CC398) is common among pig farmers. This study was conducted (i) to investigate whether pig farmers are colonized with pig-specific S. aureus genotypes other than CC398 and (ii) to survey antimicrobial resistance of S. aureus isolates from pigs and pig farmers. Fortyeight S. aureus isolates from pig farmers and veterinarians and 130 isolates from pigs collected in Western Switzerland were genotyped by spa typing and amplified fragment length polymorphism (AFLP). Antimicrobial resistance profiles were determined for representative sample of the isolates. The data obtained earlier on healthy S. aureus carriers without exposure to agriculture were used for comparison. The genotype composition of S. aureus isolates from pig farmers and veterinarians was similar to isolates from pigs with predominant AFLP clusters CC398, CC9, and CC49. The resistance to tetracycline and macrolides (clarithromycin) was common among the isolates from farmers and veterinarians (52 and 21%, respectively) and similar to resistance levels in isolates from pigs (39 and 23%, respectively). This was in contrast to isolates from persons without contact with agriculture, where no (0/128) isolates were resistant to tetracycline and 3% of the isolates were resistant to clarithromycin. MRSA CC398 was isolated from pigs (n ‫؍‬ 11) and pig farmers (n ‫؍‬ 5). These data imply that zoonotic transmission of multidrug-resistant S. aureus from pigs to farmers is frequent, and well-known MRSA transmission merely represents the tip of the iceberg for this phenomenon. We speculate that the relatively low frequency of MRSA isolation is related to lower antimicrobial use in Switzerland compared to, for example, the Netherlands.

older patients with OD presented polymorbidity and impaired health status, high prevalence of VFS signs of impaired safety of swallow and poor oral health status with high prevalence of periodontal diseases and caries. These patients are at great risk of developing AP. We recommend a policy of systematic oral health assessment in elderly patients with OD.