Aims/hypothesis
Recent studies indicate that an aberrant gut microbiota is associated with the development of type 1 diabetes, yet little is known about the microbiota in children who have diabetes ...at an early age. To this end, the microbiota of children aged 1–5 years with new-onset type 1 diabetes was compared with the microbiota of age-matched healthy controls.
Methods
A deep global analysis of the gut microbiota composition was established by phylogenetic microarray analysis using a Human Intestinal Tract Chip (HITChip).
Results
Principal component analyses highlighted the importance of age when comparing age-matched pairs. In pairs younger than 2.9 years, the combined abundance of the class Bacilli (notably streptococci) and the phylum Bacteroidetes was higher in diabetic children, whereas the combined abundance of members of
Clostridium
clusters IV and XIVa was higher in the healthy controls. Controls older than 2.9 years were characterised by a higher fraction of butyrate-producing species within
Clostridium
clusters IV and XIVa than was seen in the corresponding diabetic children or in children from the younger age groups, while the diabetic children older than 2.9 years could be differentiated by having an increased microbial diversity.
Conclusions/interpretation
The results from both age groups suggest that non-diabetic children have a more balanced microbiota in which butyrate-producing species appear to hold a pivotal position.
We sought to determine whether pre-eclampsia, spontaneous preterm birth or the delivery of infants who are small for gestational age were associated with the presence of bacterial DNA in the human ...placenta. Here we show that there was no evidence for the presence of bacteria in the large majority of placental samples, from both complicated and uncomplicated pregnancies. Almost all signals were related either to the acquisition of bacteria during labour and delivery, or to contamination of laboratory reagents with bacterial DNA. The exception was Streptococcus agalactiae (group B Streptococcus), for which non-contaminant signals were detected in approximately 5% of samples collected before the onset of labour. We conclude that bacterial infection of the placenta is not a common cause of adverse pregnancy outcome and that the human placenta does not have a microbiome, but it does represent a potential site of perinatal acquisition of S. agalactiae, a major cause of neonatal sepsis.
OBJECTIVE:The aim of the present study is to investigate the association of gut microbiota, depending on treatment method, with the development of colorectal anastomotic leakage (AL).
BACKGROUND:AL ...is a major cause for morbidity and mortality after colorectal surgery, but the mechanism behind this complication still is not fully understood.
METHODS:Bacterial DNA was isolated from 123 “donuts” of patients where a stapled colorectal anastomosis was made and was analyzed using 16S MiSeq sequencing. In 63 patients, this anastomosis was covered with a C-seal, a bioresorbable sheath stapled to the anastomosis.
RESULTS:In non-C-seal patients, AL development was associated with low microbial diversity (P = 0.002) and correspondingly with a high abundance of the dominant Bacteroidaceae and Lachnospiraceae families (P = 0.008 and 0.010, respectively). In C-seal samples, where AL rates were slightly higher (25% vs 17%), an association with the gut microbiota composition was almost undetectable. Only a few opportunistic pathogenic groups of low abundance were associated with AL in C-seal patients, in particular Prevotella oralis (P = 0.007).
CONCLUSIONS:AL in patients without a C-seal can be linked to the intestinal microbiota, in particular with a low microbial diversity and a higher abundance of especially mucin-degrading members of the Bacteroidaceae and Lachnospiraceae families. In C-seal patients, however, it seems that any potential protective benefits or harmful consequences of the gut microbiota composition in regard to wound healing are negated, as progression to AL is independent of the initially dominant bacterial composition.
The role of the intestinal microbiota as a regulator of autoimmune diabetes in animal models is well-established, but data on human type 1 diabetes are tentative and based on studies including only a ...few study subjects. To exclude secondary effects of diabetes and HLA risk genotype on gut microbiota, we compared the intestinal microbiota composition in children with at least two diabetes-associated autoantibodies (n = 18) with autoantibody-negative children matched for age, sex, early feeding history, and HLA risk genotype using pyrosequencing. Principal component analysis indicated that a low abundance of lactate-producing and butyrate-producing species was associated with β-cell autoimmunity. In addition, a dearth of the two most dominant Bifidobacterium species, Bifidobacterium adolescentis and Bifidobacterium pseudocatenulatum, and an increased abundance of the Bacteroides genus were observed in the children with β-cell autoimmunity. We did not find increased fecal calprotectin or IgA as marker of inflammation in children with β-cell autoimmunity. Functional studies related to the observed alterations in the gut microbiome are warranted because the low abundance of bifidobacteria and butyrate-producing species could adversely affect the intestinal epithelial barrier function and inflammation, whereas the apparent importance of the Bacteroides genus in development of type 1 diabetes is insufficiently understood.
A longitudinal study was undertaken in infants living in the Maela refugee camp on the Thailand-Myanmar border between 2007 and 2010. Nasopharyngeal swabs were collected monthly, from birth to 24 ...months of age, with additional swabs taken if the infant was diagnosed with pneumonia according to WHO clinical criteria. At the time of collection, swabs were cultured for Streptococcus pneumoniae and multiple serotype carriage was assessed. The bacterial 16S rRNA gene profiles of 544 swabs from 21 infants were analysed to see how the microbiota changes with age, respiratory infection, antibiotic consumption and pneumococcal acquisition. The nasopharyngeal microbiota is a somewhat homogenous community compared to that of other body sites. In this cohort it is dominated by five taxa: Moraxella, Streptococcus, Haemophilus, Corynebacterium and an uncharacterized Flavobacteriaceae taxon of 93% nucleotide similarity to Ornithobacterium. Infant age correlates with certain changes in the microbiota across the cohort: Staphylococcus and Corynebacterium are associated with the first few months of life while Moraxella and the uncharacterised Flavobacteriaceae increase in proportional abundance with age. Respiratory illness and antibiotic use often coincide with an unpredictable perturbation of the microbiota that differs from infant to infant and in different illness episodes. The previously described interaction between Dolosigranulum and Streptococcus was observed in these data. Monthly sampling demonstrates that the nasopharyngeal microbiota is in flux throughout the first two years of life, and that in this refugee camp population the pool of potential bacterial colonisers may be limited.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background. Anomalous intestinal microbiota development is supposedly associated with development of necrotizing enterocolitis (NEC). Our aim in this study was to identify the intestinal microbiota ...of patients at risk for NEC. Methods. In a prospective trial that investigated prognostic factors for development of NEC in high-risk neonates (NTR4153), 11 NEC cases were gestational age/birthweight matched with controls (ratio of 1:2). Feces were collected twice a week. We used the first feces sample of each patient (meconium), as well as the last 2 feces samples prior to development of NEC. DNA was extracted, and the bacterial 16S rRNA genes were analyzed on a MiSeq sequencer. Results. The presence and abundance of Clostridium perfringens (8.4%) and Bacteroides dorei (0.9%) in meconium were increased in neonates who developed NEC compared with controls (0.1% and 0.2%; both species, P < .001). In post-meconium samples, the abundance of staphylococci became negatively associated with NEC development (P =.1 and P =.01 for consecutive samples); Clostridium perfringens continued to be more prevalent in NEC cases. Early enteral feeding and, in particular, breast milk were correlated with an increase in lactate-producing bacilli in post-meconium samples (p = −0.45; P = .004). Conclusions. A NEC-associated gut microbiota can be identified in meconium samples; C. perfringens continues to be associated with NEC from the first meconium till just before NEC onset. In contrast, in post-meconium, increased numbers of staphylococci were negatively associated with NEC. These findings suggest causality but this causality should be verified in trials of induced infection in animals, targeted antibiotics, and/or probiotics. Clinical Trials Registration. CALIFORNIA trial, registered under trial number NTR4153 in the Dutch Trial Registry.
Group B streptococcus (GBS) is the leading cause of neonatal invasive disease worldwide. In the Netherlands incidence of the disease increased despite implementation of preventive guidelines. We ...describe a genomic analysis of 1345 GBS isolates from neonatal (age 0-89 days) invasive infections in the Netherlands reported between 1987 and 2016. Most isolates clustered into one of five major lineages: CC17 (39%), CC19 (25%), CC23 (18%), CC10 (9%) and CC1 (7%). There was a significant rise in the number of infections due to isolates from CC17 and CC23. Phylogenetic clustering analysis revealed that this was caused by expansion of specific sub-lineages, designated CC17-A1, CC17-A2 and CC23-A1. Dating of phylogenetic trees estimated that these clones diverged in the 1960s/1970s, representing historical rather than recently emerged clones. For CC17-A1 the expansion correlated with acquisition of a new phage, carrying gene encoding a putative cell-surface protein. Representatives of CC17-A1, CC17-A2 and CC23-A1 clones were identified in datasets from other countries demonstrating their global distribution.
Sublancin 168 is a highly potent and stable antimicrobial peptide secreted by the Gram-positive bacterium Bacillus subtilis. Production of sublancin gives B. subtilis a major competitive growth ...advantage over a range of other bacteria thriving in the same ecological niches, the soil and plant rhizosphere. B. subtilis protects itself against sublancin by producing the cognate immunity protein SunI. Previous studies have shown that both the sunA gene for sublancin and the sunI immunity gene are encoded by the prophage SPβ. The sunA gene is under control of several transcriptional regulators. Here we describe the mechanisms by which sunA is heterogeneously expressed within a population, while the sunI gene encoding the immunity protein is homogeneously expressed. The key determinants in heterogeneous sunA expression are the transcriptional regulators Spo0A, AbrB and Rok. Interestingly, these regulators have only a minor influence on sunI expression and they have no effect on the homogeneous expression of sunI within a population of growing cells. Altogether, our findings imply that the homogeneous expression of sunI allows even cells that are not producing sublancin to protect themselves at all times from the active sublancin produced at high levels by their isogenic neighbors. This suggests a mutualistic evolutionary strategy entertained by the SPβ prophage and its Bacillus host, ensuring both stable prophage maintenance and a maximal competitive advantage for the host at minimal costs.
A recent study by Rackaityte et al. reported evidence for a low level of bacterial colonization, specifically of Micrococcus luteus, in the intestine of second trimester human fetuses. We have ...re-analyzed their sequence data and identified a batch effect which violates the underlying assumptions of the bioinformatic method used for contamination removal. This batch effect resulted in Micrococcus not being identified as a contaminant in the original work and being falsely assigned to the fetal samples. We further provide evidence that the micrographs presented by Rackaityte et al. are unlikely to show Micrococci or other bacteria as the size of the particles shown exceeds that of related bacterial cells. Finally, phylogenetic analysis showed that the microbes cultured from the fetal samples differed significantly from those detected by sequencing. Overall, our findings show that the presence of Micrococcus in the fetal gut is not supported by the primary sequence data. Our findings underline important aspects of the nature of contamination for both sequencing and culture approaches in microbiome studies and the appropriate use of automated contamination identification tools.
During the course of history, various important lifestyle changes have caused profound transitions of the gut microbiome. These include the introduction of agriculture and animal husbandry, a shift ...from a nomadic to a more sedentary lifestyle, and recently increased levels of urbanization and a transition towards a more Western lifestyle. The latter is linked with shifts in the gut microbiome that have a reduced fermentative capability and which are commonly associated with diseases of affluence. In this study, in which 5193 subjects are included, we investigated the direction of microbiome shifts that occur in various ethnicities living in Amsterdam by comparing 1st and 2nd generation participants. We furthermore validated part of these findings with a cohort of subjects that moved from rural Thailand to the USA.
The abundance of the Prevotella cluster, which includes P. copri and the P. stercorea trophic network, diminished in the 2nd generation Moroccans and Turks but also in younger Dutch, whilst the Western-associated Bacteroides/Blautia/Bifidobacterium (BBB) cluster, which has an inverse correlation with α-diversity, increased. At the same time, the Christensenellaceae/Methanobrevibacter/Oscillibacter trophic network, which is positively associated with α-diversity and a healthy BMI, decreased in younger Turks and Dutch. Large compositional shifts were not observed in South-Asian and African Surinamese, in whom the BBB cluster is already dominant in the 1st generation, but ASV-level shifts towards certain species, associated amongst others with obesity, were observed.
The Moroccan and Turkish populations, but also the Dutch population are transitioning towards a less complex and fermentative less capable configuration of the gut microbiota, which includes a higher abundance of the Western-associated BBB cluster. The Surinamese, whom have the highest prevalence of diabetes and other diseases of affluence, are already dominated by the BBB cluster. Given the continuous increase in diseases of affluence, this devolution towards low-diversity and fermentatively less capable gut microbiome compositions in urban environments is a worrying development. Video Abstract.
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