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| 2. |
- Pettersson, B., et al.
(författare)
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Phylogenetic evidence for novel and genetically different intestinal spirochetes resembling Brachyspira aalborgi in the mucosa of the human colon as revealed by 165 rDNA analysis
- 2000
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Ingår i: Systematic and Applied Microbiology. - 0723-2020 .- 1618-0984. ; 23:3, s. 355-363
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Tidskriftsartikel (refereegranskat)abstract
- intestinal spirochetes (Brachyspira spp.) are causative agents of intestinal disorders in animals and humans. Phylogenetic analysis of cloned 16S rRNA genes from biopsies of the intestinal mucosa of the colon from two Swedish 60-years old adults without clinical symptoms revealed the presence of intestinal spirochetes. Seventeen clones from two individuals and 11 reference strains were analyzed and the intestinal spirochetes could be divided into two lineages, the Brachyspira aalborgi and the Brachyspira hyodysenteriae lineages. All of the clones grouped in the B. aalborgi lineage. Moreover, the B. aalborgi lineage could be divided into three distinct phylogenetic clusters as confirmed by bootstrap and signature nucleotide analysis. The first cluster comprised 6 clones and the type strain B. aalborgi NCTC 11492(T). The cluster 1 showed a 16S rRNA gene similarity of 99.4-99.9%. This cluster also harbored che only other strain of B. aalborgi isolated so far, namely strain W1, which was subjected to phylogenetic analysis in this work. The second cluster harbored 9 clones with a 98.7 to 99.5% range of 16S rDNA similarity ro the B. aalborgi cluster 1. Two clones branched distinct and early of the B. aalborgi, line forming the third cluster and was found to be 98.7% similar to cluster 1 and 98.3-99.1% to cluster 2. Interestingly, this shows that considerable variation of intestinal spirochetes can be found as constituents of the colonic microbiota in humans, genetically resembling B. aalborgi. The presented data aid significantly to the diagnostic and taxonomic work on these organisms.
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| 4. |
- Wang, Mei, et al.
(författare)
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Comparison of bacterial diversity along the human intestinal tract by direct cloning and sequencing of 16S rRNA genes
- 2005
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 1574-6941 .- 0168-6496. ; 54:2, s. 219-231
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial diversity of the mucosal biopsies from human jejunum, distal ileum, ascending colon and rectum were compared by analysis of PCR-amplified 16S rDNA clone libraries. A total of 347 clones from the mucosal biopsies were partially sequenced and assigned to six phylogenctic phyla of the domain Bacteria: Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria, Verrucomicrobia, and Actinobacteria. The jejunum sample had least microbial diversity compared to the other samples and a trend towards highest diversity in ascending colon was observed. The clone libraries of distal ileum, ascending colon and rectum were not significantly different from each other (P > 0.0043), but they differed significantly from the jejunum library (P = 0.001). The population of sequences retrieved from jejunal biopsies was dominated by sequences closely related to Streptococcus (67%), while the population of sequences derived from distal ileum, ascending colon and rectum were dominated by sequences affiliated with Bacteroidetes (27-49%), and Clostridium clusters XlVa (20-34%) and IV (7-13%). The results indicate that the microbial community in jejunum is different from those in distal ileum, ascending colon and rectum, and that the major phylogenetic groups are similar from distal ileum to rectum. (C) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
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| 5. |
- Wang, Mei, et al.
(författare)
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High Proportions of Proinflammatory Bacteria on the Colonic Mucosa in a Young Patient with Ulcerative Colitis as Revealed by Cloning and Sequencing of 16S rRNA Genes.
- 2007
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Ingår i: Digestive Diseases and Sciences. - : Springer Science and Business Media LLC. - 1573-2568 .- 0163-2116. ; 52, s. 620-627
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenesis of ulcerative colitis (UC) remains unknown. It is thought to be due to an abnormal and uncontrolled immune response to normally occurring constituents of the intestine. Microbial agents appear to be involved in the pathogenesis and intestinal bacteria seem to be an important factor in the development and chronicity. The aim of this study was to investigate the colonic microbiota of a patient with UC. The colonic tissues were taken during surgery from a 12-year-old girl suffering from UC. The microbiota on the colonic samples was studied by cloning and sequencing of amplified 16S rRNA genes. Compared with healthy subjects, alteration of the dominant bacterial group was observed in the UC patient. We found a high incidence of Enterobacteriaceae, Bacteroides fragilis, and the single phylotype of the Faecalibacterium prausnitzii-like "Butyrate-producing bacterium" L2-6. Furthermore, there was a substantial presence of Pseudomonas aeruginosa in the present case of UC. The high proportion of adverse proinflammatory species is striking in the present case compared with more normal situations. Even if those bacteria are not the cause of the UC, they most probably enhance the symptoms of the disease.
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| 6. |
- Wang, Mei, et al.
(författare)
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Identification of the translocating bacteria in rats with acute liver injury and their relation to the bacterial flora of the intestinal mucosa
- 2001
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Ingår i: APMIS : acta pathologica, microbiologica, et immunologica Scandinavica. - : Wiley. - 1600-0463. ; 109:7-8, s. 551-558
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Tidskriftsartikel (refereegranskat)abstract
- The bacterial flora of the intestine and the bacteria found in liver, mesenteric lymph nodes, portal and arterial blood after D-galactosamine-induced liver injury, with and without pretreatment with Lactobacillus plantarum DSM 9843, were studied in the rat. Dominating representatives were identified to species level by 16S rDNA sequencing and typed by randomly amplified polymorphic DNA (RAPD) and by restriction endonuclease analysis (REA) for strain definition. It was proven that bacterial strains from the intestine occur at extraintestinal sites after liver injury. Lactobacillus spp. dominated the intestinal flora and were also the most frequently found genus in the liver and the mesenteric lymph nodes. Some of the blood isolates, identified as Staphylococcus aureus, Proteus vulgaris and Bacteroides merdae, were not found as a dominating part of the mucosal flora. Treatment with L. plantarum before liver injury decreased translocation and made the intestinal flora increasingly dominated by lactobacilli.
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| 7. |
- Wang, Mei, et al.
(författare)
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Reduced diversity in the early fecal microbiota of infants developing atopic eczema
- 2008
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Ingår i: Journal of Allergy and Clinical Immunology. - : Elsevier BV. - 1097-6825 .- 0091-6749. ; 121:1, s. 129-134
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Tidskriftsartikel (refereegranskat)abstract
- Background It might be that early intestinal colonization by bacteria in westernized infants fails to give rise to sufficient immune stimulation to support maturation of regulatory immune mechanisms. Objective The purpose of the present study was to characterize the very early infantile microbiota by using a culture-independent approach and to relate the colonization pattern to development of atopic eczema in the first 18 months of life. Methods Fecal samples were collected from 35 infants at 1 week of age. Twenty infants were healthy, and 15 infants were given diagnoses of atopic eczema at the age of 18 months. The fecal microbiota of the infants was compared by means of terminal restriction fragment length polymorphism (T-RFLP) and temporal temperature gradient gel electrophoresis (TTGE) analysis of amplified 16S rRNA genes. Results By means of T-RFLP analysis, the median number of peaks, Shannon-Wiener index, and Simpson index of diversity were significantly less for infants with atopic eczema than for infants remaining healthy in the whole group and for the Swedish infants when AluI was used for digestion. The same was found when TTGE patterns were compared. In addition, TTGE analysis showed significantly less bands and lower diversity indices for the British atopic infants compared with those of the control subjects. Conclusion There is a reduced diversity in the early fecal microbiota of infants with atopic eczema during the first 18 months of life.
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| 8. |
- Wang, Mei, et al.
(författare)
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T-RFLP combined with principal component analysis and 16S rRNA gene sequencing: an effective strategy for comparison of fecal microbiota in infants of different ages
- 2004
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 1872-8359 .- 0167-7012. ; 59:1, s. 53-69
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Tidskriftsartikel (refereegranskat)abstract
- The fecal microbiota of two healthy Swedish infants was monitored over time by terminal restriction fragment length polymorphism (T-RFLP) analysis of amplified 16S rRNA genes. Principal component analysis (PCA) of the T-RFLP profiles revealed that the fecal flora in both infants was quite stable during breast-feeding and a major change occurred after weaning. The two infants had different sets of microbiota at all sampling time points. 16S rDNA clone libraries were constructed and the predominant terminal restriction fragments (T-RFs) were identified by comparing T-RFLP patterns in the fecal community with that of corresponding 16S rDNA clones. Sequence analysis indicated that the infants were initially colonized mostly by members of Enterobacteriaceae, Veillonella, Enterococcus, Streptococcus, Staphylococcus and Bacteroides. The members of Enterobacteriaceae and Bacteroides were predominant during breast-feeding in both infants. However, Enterobacteriaceae decreased while members of clostridia increased after weaning. T-RFLP in combination with PCA and 16S rRNA gene sequencing was shown to be an effective strategy for comparing fecal microbiota in infants and pointing out the major changes. (C) 2004 Elsevier B.V. All rights reserved.
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