| 1. |
- Bankvall, Maria, et al.
(författare)
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The oral microbiota of patients with recurrent aphthous stomatitis.
- 2014
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Ingår i: Journal of oral microbiology. - : Informa UK Limited. - 2000-2297. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Specific pathogenic bacteria have been implicated in recurrent aphthous stomatitis (RAS), a chronic inflammatory condition characterised by ulcerations in the oral mucosa. However, the aetiology behind this condition still remains unclear.
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| 2. |
- Hesselmar, Bill, 1955, et al.
(författare)
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Pacifier Cleaning Practices and Risk of Allergy Development.
- 2013
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Ingår i: Pediatrics. - : American Academy of Pediatrics (AAP). - 1098-4275 .- 0031-4005. ; 131:6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:Immune stimulation through exposure to commensal microbes may protect against allergy development. Oral microbes may be transferred from parents to infants via pacifiers. We investigated whether pacifier cleaning practices affected the risk of allergy development.METHODS:A birth-cohort of 184 infants was examined for clinical allergy and sensitization to airborne and food allergens at 18 and 36 months of age and, in addition, promptly on occurrence of symptoms. Pacifier use and pacifier cleaning practices were recorded during interviews with the parents when the children were 6 months old. The oral microbiota of the infants was characterized by analysis of saliva samples collected at 4 months of age.RESULTS:Children whose parents "cleaned" their pacifier by sucking it (n = 65) were less likely to have asthma (odds ratio [OR] 0.12; 95% confidence interval [CI] 0.01-0.99), eczema (OR 0.37; 95% CI 0.15-0.91), and sensitization (OR 0.37; 95% CI 0.10-1.27) at 18 months of age than children whose parents did not use this cleaning technique (n = 58). Protection against eczema remained at age 36 months (hazard ratio 0.51; P = .04). Vaginal delivery and parental pacifier sucking yielded independent and additive protective effects against eczema development. The salivary microbiota differed between children whose parents cleaned their pacifier by sucking it and children whose parents did not use this practice.CONCLUSIONS:Parental sucking of their infant's pacifier may reduce the risk of allergy development, possibly via immune stimulation by microbes transferred to the infant via the parent's saliva.
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| 3. |
- Sjöberg, Fei, et al.
(författare)
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Comparison between terminal-restriction fragment length polymorphism (T-RFLP) and quantitative culture for analysis of infants' gut microbiota
- 2013
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Ingår i: Journal of Microbiological Methods. - : Elsevier BV. - 0167-7012 .- 1872-8359. ; 94:1, s. 37-46
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Tidskriftsartikel (refereegranskat)abstract
- The infantile intestinal microbiota is a major stimulus for immune maturation. Both culture and DNA-based methods can be used for microbiota characterization, but few studies have systematically compared their performance for analysis of the gut microbiota. Here, we examined fecal samples obtained on six occasions between one week and 12 months of age from six vaginally delivered infants. After quantitative aerobic and anaerobic culture of the samples on selective and non-selective media, DNA was extracted from the fecal samples and analyzed regarding 16S rRNA gene polymorphism by terminal-restriction fragment length polymorphism (T-RFLP). A database was constructed for direct identification of T-RFLP peaks by analysis of pure-culture bacteria and analysis of a limited number of samples by 16S rRNA cloning and sequencing. Bacterial genera present at >10(6) CFU/g feces, as determined by quantitative culture, were generally readily detected by T-RFLP, while culture on selective media was more sensitive in detecting facultative anaerobes with lower population counts. In contrast, T-RFLP more readily than culture detected several anaerobic species, also taxa that could not be identified using the database. T-RFLP readily identified bacteria to the genus level and also provided some sub-genus discrimination. Both T-RFLP and culture identified Bifidobacterium, Clostridium and Bacteroides spp. among the most common colonizers of the infantile microbiota throughout the first year of life. T-RFLP analysis showed that microbiota complexity was high in the first weeks of life, declined to a minimum at 1-2 months of age, and thereafter increased again. Principal component analysis revealed that early samples (1 week-6 months) chiefly differed between individual infants, while 12-month samples were similar between children, but different from the early samples. Our results indicate that T-RFLP has high sensitivity and adequate taxonomic discrimination capacity for analysis of gut microbiota composition, but that both culture and molecular based analysis have limitations and both approaches may be needed to obtain a full picture of the complex gut microbiota.
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| 4. |
- Sjöberg, Fei
(författare)
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Microbiota of the alimentary tract of children - implications for allergy and inflammatory bowel disease
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Allergy, which is the most common chronic disease in Swedish children and adolescents, is associated with a high standard of living and Western lifestyle. According to the hygiene hypothesis, allergy is due to inadequate stimulation of the immune system by microbes during early childhood, leading to failed maturation of the immune system. The incidences of inflammatory bowel diseases, i.e., ulcerative colitis and Crohn’s disease, have also increased dramatically in Western countries over the last few decades, and currently, these diseases are often diagnosed already in childhood. Epidemiological evidence suggests links between alterations to the intestinal microbiota and these diseases. Thus, studies of the composition of the bacterial microbiota in infants and young children are of relevance for the pathogenesis of both allergic diseases and inflammatory bowel diseases. In this thesis, quantitative culture and DNA-based methods are compared for their abilities to characterize the gut microbiota in infants. Terminal-Restriction Fragment Length Polymorphism (T-RFLP) is based on differences in the 16S rRNA gene sequences between bacteria, as revealed by differences in fragment sizes after restriction enzyme digestion. A database was constructed to identify bacteria based on their fragment sizes. Multi-parallel sequencing of the 16S rRNA gene by pyrosequencing and T-RFLP were compared for sensitivity with quantitative culture of infant fecal samples. Bacterial genera that were present at >106 colony forming units/g feces, as determined by culture, were generally readily detected by DNA-based methods, with the exception of bifidobacteria, which generated only one sequence read per 108 viable bacteria. Clinically and immunologically relevant facultative bacteria, e.g., staphylococci, were often missed by the DNA-based methods due to having low counts in the fecal samples. The studies presented in this thesis indicate that cultivation and molecular-based assays are complementary in generating an overall picture of the complex gut microbiota. In the ALLERGYFLORA cohort study, T-RFLP was used to analyze the salivary microbiota in 4-month-old infants whose parents had the habit of “cleaning” their pacifier by sucking on it, and of control children whose parents did not have this habit. Sharing of the pacifier between parent and infant was associated with reduced risk of the child developing an allergy and altered salivary microbiota in the child. We hypothesize that the oral bacteria transmitted from the parents stimulate the child's immune system in such a way that allergy development is avoided. Samples of the duodenal fluids of children with newly diagnosed and untreated inflammatory bowel diseases (ulcerative colitis and Crohn's disease) and controls (having functional bowel disorders without signs of intestinal inflammation) were analyzed by culture and pyrosequencing. The microbiota of children with ulcerative colitis displayed lower bacterial diversity than that of the control children, and certain bacterial groups were less abundant in the former group. Taken together, the studies presented in this thesis suggest that the compositions of the commensal microbiota in the oral cavity and small intestine affect the risk of developing immunoregulatory diseases, such as allergies and inflammatory bowel diseases.
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