-
Journal of Neurogastroenterology and... Apr 2020Studies that investigated esophageal microbiomes are limited when compared to those on intestinal microbiomes. Nevertheless, several studies have investigated the... (Review)
Review
Studies that investigated esophageal microbiomes are limited when compared to those on intestinal microbiomes. Nevertheless, several studies have investigated the relationship between esophageal microbiomes and various esophageal diseases, owing to the advancement of next-generation sequencing techniques. is the most common bacterial taxon in a normal esophagus. Additionally, , , , and are also found. However, gram-negative bacteria, including , are more abundant in a diseased esophagus, such as in gastroesophageal reflux disease and Barrett's esophagus. This systematic review aims to summarize current evidences on esophageal microbiomes in various esophageal diseases.
PubMed: 32235026
DOI: 10.5056/jnm19240 -
Alimentary Pharmacology & Therapeutics Mar 2020Proton pump inhibitors (PPI) are widely used to treat acid-related disorders of the upper gastrointestinal tract. However, large observational studies have raised...
BACKGROUND
Proton pump inhibitors (PPI) are widely used to treat acid-related disorders of the upper gastrointestinal tract. However, large observational studies have raised concerns about PPI-associated adverse events. In recent years, data from next-generation sequencing studies suggested that PPIs affect the composition of the intestinal microbiota, while a balanced gut microbiome is essential for maintaining health.
AIM
To review the available evidence from next-generation sequencing studies on the effect of PPIs on the intestinal microbiome and to discuss possible implications of PPI-induced dysbiosis in health and disease.
METHODS
A systematic review was conducted following the recommendations of the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement. A PubMed query yielded 197 results. 19 publications met the prespecified eligibility criteria.
RESULTS
Twelve observational study cohorts with 708 PPI users and 11 interventional cohorts with 180 PPI users were included in the review. In most studies, PPI treatment did not affect microbiological richness and diversity, but was associated with distinct taxonomic alterations: In the upper gastrointestinal tract, PPI users showed overgrowth of orally derived bacteria, mostly Streptococcaceae (findings based on six independent cohorts with 126 PPI users). In faecal samples, PPIs increased multiple taxa from the orders Bacillales (eg, Staphylococcaceae), Lactobacillales (eg, Enterococcaceae, Lactobacillaceae, Streptococcaceae) and Actinomycetales (eg, Actinomycetaceae, Micrococcaceae), the families Pasteurellaceae and Enterobacteriaceae and the genus Veillonella. Taxa decreased by PPIs include Bifidobacteriaceae, Ruminococcaceae, Lachnospiraceae and Mollicutes (findings in faecal samples based on 19 independent cohorts with 790 PPI users).
CONCLUSION
PPI use is associated with moderate alterations to upper and distal gut microbiota. The available data suggest that PPI-induced hypochlorhydria facilitates colonization of more distal parts of the digestive tract by upper gastrointestinal microbiota.
Topics: Bacteria; Cohort Studies; DNA, Bacterial; Dysbiosis; Feces; Gastrointestinal Microbiome; Gastrointestinal Tract; High-Throughput Nucleotide Sequencing; Humans; Observational Studies as Topic; Proton Pump Inhibitors; Sequence Analysis, DNA
PubMed: 31990420
DOI: 10.1111/apt.15604 -
Gastroenterology Mar 2020Altering the intestinal microbiota has been proposed as a treatment for inflammatory bowel diseases (IBDs), but there are no established associations between specific...
BACKGROUND & AIMS
Altering the intestinal microbiota has been proposed as a treatment for inflammatory bowel diseases (IBDs), but there are no established associations between specific microbes and IBD. We performed a systematic review to identify frequent associations.
METHODS
We searched the MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials databases, through April 2, 2018 for studies that compared intestinal microbiota (from fecal or colonic or ileal tissue samples) among patients (adult or pediatric) with IBD vs healthy individuals (controls). The primary outcome was difference in specific taxa in fecal or intestinal tissue samples from patients with IBD vs controls. We used the Newcastle-Ottawa scale to assess the quality of studies included in the review.
RESULTS
We identified 2631 citations; 48 studies from 45 articles were included in the analysis. Most studies evaluated adults with Crohn's disease or ulcerative colitis. All 3 studies of Christensenellaceae and Coriobacteriaceae and 6 of 11 studies of Faecalibacterium prausnitzii reported a decreased amount of those organisms compared with controls, whereas 2 studies each of Actinomyces, Veillonella, and Escherichia coli revealed an increased amount in patients with Crohn's disease. For patients with ulcerative colitis, Eubacterium rectale and Akkermansia were decreased in all 3 studies, whereas E coli was increased in 4 of 9 studies. The microbiota diversity was either decreased or not different in patients with IBD vs controls. Fewer than 50% of the studies stated comparable sexes and ages of cases and controls.
CONCLUSIONS
In a systematic review, we found evidence for differences in abundances of some bacteria in patients with IBD vs controls, but we cannot make conclusions due to inconsistent results and methods among studies. Further large-scale studies, with better methods of assessing microbe populations, are needed.
Topics: Colitis, Ulcerative; Crohn Disease; Feces; Gastrointestinal Microbiome; Humans; Inflammatory Bowel Diseases; Intestines
PubMed: 31812509
DOI: 10.1053/j.gastro.2019.11.294 -
Environmental Microbiology Reports Apr 2020In recent years, there has been an increase in studies on the implications of gut microbiota (GM) on the behaviour of children with autism spectrum disorders (ASD) due... (Review)
Review
In recent years, there has been an increase in studies on the implications of gut microbiota (GM) on the behaviour of children with autism spectrum disorders (ASD) due to a dysbiosis in GM that can trigger onset, development or progression of ASD through the microbiota-gut-brain axis. The aim of this study is to carry out a systematic review of articles from the last 6 years that analyse GM in children with ASD compared to GM in control groups. Children with ASD showed a higher abundance of Roseburia and Candida genera, and lower abundance of Dialister, Bilophila, Veillonella, Streptococcus, Coprococcus and Prevotella genera. Those differences can be attributed to factors such as different nationalities, nature of control groups, place where the sample was taken, gastrointestinal (GI) problems or bacterial detection methods. It is still too early to define a specific GM profile of children with ASD, and future studies should focus on homogenizing the characteristics of samples and control groups. Furthermore, new multicentre studies should also focus on the impact of GM on GI physiology, neurophysiology and behaviour of children with ASD, and on performing psychometric analyses of the correlation between the severity of ASD behavioural symptoms and GM profiles.
Topics: Autism Spectrum Disorder; Bacteria; Bilophila; Child; Child, Preschool; Clostridiales; Dysbiosis; Female; Gastrointestinal Diseases; Gastrointestinal Microbiome; Humans; Male; Prevotella; Streptococcus; Veillonellaceae
PubMed: 31713352
DOI: 10.1111/1758-2229.12810 -
Medicina (Kaunas, Lithuania) Jul 2019: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired communication, social interaction disorder, and repetitive behavior.... (Meta-Analysis)
Meta-Analysis
: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired communication, social interaction disorder, and repetitive behavior. Dysbiotic gut microbiota (GM) could be a contributing factor to the appearance of ASD, as gastrointestinal (GI) symptoms are comorbidities frequently reported in ASD. As there is a lack of reviews about the role played by GM in the GI symptoms of ASD, this work aimed to carry out a systematic review of current studies comparing the GM of children with ASD and GI symptoms with those of healthy controls in the last six years. The systematic review was performed following the PRISMA guidelines. The databases chosen were Web of Science, Scopus, PubMed, and PsycINFO, and the keywords were (gut* OR intestine* OR bowel* OR gastrointestinal*) AND (microbiota* OR microflora* OR bacteria* OR microbiome* OR flora* OR bacterial* OR bacteria* OR microorganism* OR feces* OR stool*) AND (autistic* OR autism* OR ASD*). : A total of 16 articles were included. Ten articles performed correlations analysis between GI symptoms and ASD. Among those 10 articles, 7 found differences between the GI symptoms present in children with ASD and healthy controls. The most common GI symptom was constipation. Among the seven articles that found differences, three performed correlations analysis between GI symptoms and gut microbe abundance. , , , and showed higher and lower abundance, respectively, in children with ASD and GI symptoms in more than one article. , , , , , , and / ratios showed abundance discrepancies. : It is still too early to draw a conclusion about the gut microbes involved in GI symptoms of ASD. Future research should consider the relationship between ASD behavior, GM, and GI symptoms in a multidisciplinary way and homogenize sample characteristics.
Topics: Autism Spectrum Disorder; Gastrointestinal Microbiome; Gastrointestinal Tract; Humans; Syndrome
PubMed: 31357482
DOI: 10.3390/medicina55080408 -
Translational Psychiatry Jan 2019At present, the pathophysiology of autism spectrum disorder (ASD) remains unclear. Increasing evidence suggested that gut microbiota plays a critical role in...
At present, the pathophysiology of autism spectrum disorder (ASD) remains unclear. Increasing evidence suggested that gut microbiota plays a critical role in gastrointestinal symptoms and behavioral impairment in ASD patients. The primary aim of this systematic review is to investigate potential evidence for the characteristic dysbiosis of gut microbiota in ASD patients compared with healthy controls (HCs). The MEDLINE, EMBASE, Web of Science and Scopus were systematically searched before March 2018. Human studies that compared the composition of gut microbiota in ASD patients and HCs using culture-independent techniques were included. Independent data extraction and quality assessment of studies were conducted according to PRISMA statement and Newcastle-Ottawa Scale. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to infer biological functional changes of the shifted microbiota with the available data in four studies. Sixteen studies with a total sample size of 381 ASD patients and 283 HCs were included in this systematic review. The quality of the studies was evaluated as medium to high. The overall changing of gut bacterial community in terms of β-diversity was consistently observed in ASD patients compared with HCs. Furthermore, Bifidobacterium, Blautia, Dialister, Prevotella, Veillonella, and Turicibacter were consistently decreased, while Lactobacillus, Bacteroides, Desulfovibrio, and Clostridium were increased in patients with ASD relative to HCs in certain studies. This systematic review demonstrated significant alterations of gut microbiota in ASD patients compared with HCs, strengthen the evidence that dysbiosis of gut microbiota may correlate with behavioral abnormality in ASD patients. However, results of inconsistent changing also existed and further big-sampled well-designed studies are needed. Generally, as a potential mediator of risk factors, the gut microbiota could be a novel target for ASD patients in the future.
Topics: Animals; Autism Spectrum Disorder; Dysbiosis; Gastrointestinal Microbiome; Humans
PubMed: 30696816
DOI: 10.1038/s41398-019-0389-6 -
BMC Infectious Diseases Jan 2019Previous studies demonstrated that the diversity and composition of respiratory microbiota in TB patients were different from healthy individuals. Therefore, the aim of... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Previous studies demonstrated that the diversity and composition of respiratory microbiota in TB patients were different from healthy individuals. Therefore, the aim of the present analysis was to estimate the relative proportion of respiratory microbiota at phylum and genus levels among TB cases and healthy controls.
METHODS
The PubMed and Google Scholar online databases were searched to retrieve relevant studies for the analysis. The statistical analysis was done using STATA version 11, pooled estimates are presented using graphs. The summary of findings in included studies is also presented in Table 1.
RESULTS
The phylum level analysis shows that the pooled proportions of Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, and Crenarchaeota were determined among tuberculosis patients and healthy controls. In brief, Firmicutes, and Proteobacteria were the most abundant bacterial phyla in both TB cases and healthy controls, composing 39.9 and 22.7% in TB cases and 39.4 and 19.5% in healthy controls, respectively. The genus level analysis noted that Streptococcus (35.01%), Neisseria (27.1%), Prevotella (9.02%) and Veillonella (7.8%) were abundant in TB patients. The Prevotella (36.9%), Gammaproteobacteria (22%), Streptococcus (19.2%) and Haemophilus (15.4%) were largely seen in healthy controls. Interestingly, Veillonella, Rothia, Leuconostoc were unique to TB cases, whereas Lactobacillus, and Gammaproteobacteria, Haemophilus, and Actinobacillus were identified only in healthy controls.
CONCLUSION
The composition of the respiratory microbiota in TB patients and healthy controls were quite different. More deep sequencing studies are needed to explore the microbial variation in the respiratory system in connection with TB.
Topics: Bacteria; Humans; Microbiota; Respiratory System; Tuberculosis, Pulmonary
PubMed: 30683056
DOI: 10.1186/s12879-019-3712-1 -
Oral Surgery, Oral Medicine, Oral... Jun 2018Chemotherapy is a type of systemic treatment that inhibits neoplastic cells (cancer cells), produces immunosuppression, and may lead to changes in the oral mucosa and,... (Review)
Review
OBJECTIVE
Chemotherapy is a type of systemic treatment that inhibits neoplastic cells (cancer cells), produces immunosuppression, and may lead to changes in the oral mucosa and, consequently, in the oral microbiota. The aim of this systematic review was to analyze, in the scientific literature, evidence of the impact of chemotherapy on the oral microbiota.
STUDY DESIGN
The authors conducted a search in PubMed/MEDLINE, Scientific Electronic Library Online (SciELO), LILACS, ScienceDirect, Web of Science, and Cochrane Library; to identify studies that discussed change in the oral microbiota of patients with during chemotherapy. Articles published in English until July 2017 were included. The quality of a study was assessed by using the Ottawa-Newcastle scale.
RESULTS
Of 5252 articles potentially relevant to this review, 17 were included in this study. Of the 17 studies included, 16 had used culture techniques, and 1 had used genetic sequencing. The most frequently observed bacteria were aerobic gram-negative (Klebsiella spp., Escherichia coli, Enterobacter, Pseudomonas spp.), anaerobic gram-negative (Veillonella spp., Capnocytophaga), and gram-positive bacteria (Streptococcus spp., Staphylococcus spp.).
CONCLUSIONS
During chemotherapy, patients with cancer present a more complex oral microbiota under favorable conditions for their development during immunosuppression, and these may be responsible for different serious local or systemic pathologies.
Topics: Bacterial Load; Humans; Microbiota; Mouth Mucosa; Neoplasms
PubMed: 29566996
DOI: 10.1016/j.oooo.2018.02.008 -
International Journal of Gynecological... Sep 2017Worldwide, 1,470,900 women are diagnosed yearly with a gynecological malignancy (21,000 in the UK). Some patients treated with pelvic radiotherapy develop chronic... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND AND AIM
Worldwide, 1,470,900 women are diagnosed yearly with a gynecological malignancy (21,000 in the UK). Some patients treated with pelvic radiotherapy develop chronic changes in their bowel function. This systematic review summarizes current research on the impact of cancer treatment on the gut and vaginal microbiome in women with a gynecological malignancy.
METHODS
The Preferred reporting Items for Systematic Reviews and Meta-analyses guidelines for systematic reviews were used to ensure transparent and complete reporting. Quantitative studies exploring the gut or vaginal microbiome in this patient cohort were included. Animal studies were excluded. There were no language restrictions.
RESULTS
No studies examined the possible effects of surgery or chemotherapy for gynecological cancers on the gut or vaginal microbiome.Three prospective cohort studies were identified using sequencing of changes in the gut microbiome reporting on a total of 23 women treated for gynecological cancer. All studies included patients treated with radiotherapy with a dosage ranging from 43.0 to 54.0 Gy. Two studies assessed gastrointestinal toxicity formally; 8 women (57%) developed grade 2 or 3 diarrhea during radiotherapy. The outcomes suggest a correlation between changes in the intestinal microbiome and receiving radiotherapy and showed a decrease in abundance and diversity of the intestinal bacterial species. Before radiotherapy, those who developed diarrhea had an increased abundance of Bacteroides, Dialister, and Veillonella (P < 0.01), and a decreased abundance of Clostridium XI and XVIII, Faecalibacterium, Oscillibacter, Parabacteroides, Prevotella, and unclassified bacteria (P < 0.05).
CONCLUSION
The limited evidence to date implies that larger studies including both the vaginal and gut microbiome in women treated for a gynecological malignancy are warranted to explore the impact of cancer treatments on the microbiome and its relation to developing long-term gastrointestinal toxicity. This may lead to new avenues to stratify those at risk and explore personalized treatment options and prevention of gastrointestinal consequences of cancer treatments.
Topics: Cohort Studies; Female; Gastrointestinal Microbiome; Genital Neoplasms, Female; Humans; Prospective Studies; Vagina
PubMed: 28590950
DOI: 10.1097/IGC.0000000000000999