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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.
PEDIATRICS 05/2013; · 4.47 Impact Factor
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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 faecal samples obtained on six occasions between one week and 12months 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 faecal 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 faeces, 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 1-2months of age, and thereafter increased again. Principal component analysis revealed that early samples (1wk-6mo) chiefly differed between individual infants, while 12months 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.
Journal of microbiological methods 04/2013; · 2.43 Impact Factor
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ABSTRACT: Germ-free animal models have demonstrated that commensal bacterial colonization of the intestine induces B cell differentiation and activation. Whether colonization with particular bacterial species or groups is associated with B cell development during early childhood is not known. In a prospective newborn/infant cohort including 65 Swedish children, we examined the numbers and proportions of CD20(+), CD5(+), and CD27(+) B cells in blood samples obtained at several time points during the first 3 y of life using flow cytometry. Fecal samples were collected and cultured quantitatively for major facultative and anaerobic bacteria at 1, 2, 4, and 8 wk of life. We found that the numbers of CD20(+) B cells and CD5(+)CD20(+) B cells reached their highest levels at 4 mo, whereas CD20(+) B cells expressing the memory marker CD27 were most numerous at 18 and 36 mo of age. Using multivariate analysis, we show that early colonization with Escherichia coli and bifidobacteria were associated with higher numbers of CD20(+) B cells that expressed the memory marker CD27 at 4 and 18 mo of age. In contrast, we were unable to demonstrate any relation between bacterial colonization pattern and numbers of CD20(+) or CD5(+)CD20(+) B cells. These results suggest that the intestinal bacterial colonization pattern may affect the B cell maturation also in humans, and that an early gut microbiota including E. coli and bifidobacteria might promote this maturation.
The Journal of Immunology 04/2012; 188(9):4315-22. · 5.79 Impact Factor
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ABSTRACT: Lactobacilli are present in the intestine and oral cavity of most adults. Secretory IgA in mucosal secretions may provide carbohydrate receptors for bacterial adhesins. Here, oral and faecal samples from 33 IgA-deficient individuals and 34 controls were cultured for lactobacilli, which were identified using species-specific PCR or partial 16S rDNA sequencing and tested for expression of mannose-specific adhesins. Lactobacilli were found in the oral cavity of 76% of IgA-deficient and 85% of control individuals. Lactobacillus paracasei and Lactobacillus gasseri dominated in both groups. Lactobacillus fermentum was less common in IgA-deficient individuals than in controls (p=0.0055) and Lactobacillus salivarius was less common in symptomatic than in healthy IgA-deficient individuals (p=0.0051). Faecal samples yielded lactobacilli in most individuals. L. paracasei was most frequent, followed by L. gasseri and Lactobacillus plantarum. Mannose-specific adhesins were expressed more frequently by oral than by faecal isolates (p=0.032) and oral isolates adhered in higher numbers than faecal isolates (46 vs. 14 bacteria/cell, p=0.0038). Faecal isolates from IgA-deficient individuals more frequently expressed mannose-specific adhesins than faecal isolates from controls (p=0.039). Mannose-specific adhesins may be a colonisation factor in the oral cavity, and the presence of secretory IgA may modify adhesin expression. However, secretory IgA seems to have little influence on Lactobacillus species distribution.
International journal of medical microbiology: IJMM 01/2012; 302(1):53-60. · 2.80 Impact Factor
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ABSTRACT: In adults, a majority of FOXP3(+) T(regs) expresses CTLA-4, and this costimulatory molecule is essential to control the expansion of other T cells. However, it remains to be investigated whether FOXP3(+) and/or CTLA-4(+) T(regs) are associated with the expression of memory markers and homing receptors on CD4(+) T cells. Thus, in a prospective newborn-infant cohort study, we examined the proportions of FOXP3(+) and CTLA-4(+) T(regs) within the CD4(+)CD25(+) T cell population and the fractions of CD4(+) T cells that expressed CD45RA, CD45RO, HLA-DR, α(4)β(7), CD62L, and CCR4 at several time-points during the first 3 years of life using flow cytometry. With the use of multivariate factor analysis, we found that a high proportion of FOXP3(+) or CTLA-4(+) T(regs) during the first 18 months of life was associated positively with the fraction of T cells that expressed a naïve phenotype (CD45RA and α(4)β(7)) and inversely related to the fraction of T cells that expressed a memory phenotype (CD45RO and CCR4) later in childhood. In conclusion, FOXP3(+) or CTLA-4(+) T(regs) may modulate CD4(+) T cell activation and homing receptor expression in children.
Journal of leukocyte biology 09/2011; 90(6):1133-40. · 4.99 Impact Factor
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Forough L Nowrouzian,
Olivier Dauwalder,
Helene Meugnier,
Michele Bes,
Jerome Etienne,
François Vandenesch,
Erika Lindberg,
Bill Hesselmar,
Robert Saalman,
Inga-Lisa Strannegård,
Nils Aberg, Ingegerd Adlerberth,
Agnes E Wold,
Gerard Lina
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ABSTRACT: Staphylococcus aureus is a pathogen and a skin commensal that is today also common in the infant gut flora. We examine the role of S. aureus virulence factors for gut colonization. S. aureus isolated from quantitative stool cultures of 49 Swedish infants followed from birth to 12 months of age were assessed for 30 virulence-associated genes, spa type, and agr allele by serial polymerase chain reaction (PCR) assays. Strains carrying genes encoding collagen-binding protein, and the superantigens S. aureus enterotoxin O/M (SEO/SEM) had higher stool counts than strains lacking these genes, whereas genes for S. aureus enterotoxin A (SEA) were associated with low counts. A cluster of strains belonging to agr allele I and the spa clonal cluster 630 (spa-CC 630) that carried genes encoding SEO/SEM, SEC, collagen-binding protein, and elastin-binding protein were all long-time colonizers. Thus, certain S. aureus virulence factors might promote gut colonization.
The Journal of Infectious Diseases 09/2011; 204(5):714-21. · 6.41 Impact Factor
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ABSTRACT: Virulence-associated genes in bacteria are often located on chromosomal regions, termed pathogenicity islands (PAIs). Several PAIs are found in Escherichia coli strains that cause extraintestinal infections, but their role in commensal bowel colonization is unknown. Resident strains are enriched in adhesins (P fimbriae and type 1 fimbriae), capsular antigens (K1 and K5), hemolysin, and aerobactin and mostly belong to phylogenetic group B2. Here, we investigated whether six pathogenicity islands and the virulence determinants malX and usp are associated with fitness of E. coli in the infant bowel microbiota. E. coli strains isolated from stools of 130 Swedish infants during the first year of life were examined for their carriage of PAI markers, malX, and usp by PCR. Carriage was related to strain persistence: long-term colonizers (≥12 months) carried significantly more of PAI II from strain CFT703 (II(CFT703)), IV(536,) and II(J96) and malX and usp than intermediate colonizers (1 to 11 months) and transient strains (<3 weeks). The accumulation of PAI markers in each individual strain correlated positively with its time of persistence in the colon. Phylogenetic group B2 accounted for 69% of long-term colonizers, 46% of intermediate colonizers and 14% of transient strains. These results support the hypothesis that some bacterial traits contributing to extraintestinal infections have in fact evolved primarily because they increase the fitness of E. coli in its natural niche, the colon; accordingly, they may be regarded as fitness islands in the gut.
Applied and environmental microbiology 02/2011; 77(7):2303-8. · 3.69 Impact Factor
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ABSTRACT: B cell gut-homing is mainly mediated by α4β7, CCR9 and CCR10. We here studied the expression of these receptors on B cells from cord blood and from peripheral blood at 1, 4, 18 and 36 months of age in a prospective cohort of Swedish infants. The proportion of all B cells expressing α4β7 as well as the fraction of CCR10+ B cells expressing α4β7 was highest in early infancy. Nearly all naïve B cells in all age groups expressed α4β7, whereas the expression on class-switched B cells decreased with age. Moreover, the proportion of both IgA+ and IgG+ B cells expressing α4β7, CCR9 and CCR10 were higher during the first months when compared to adults. In conclusion, the high fraction of circulating IgA+ and IgG+ B cells expressing CCR9 and CCR10 in the first months of life indicates activation of naïve B cells in the gut, coinciding with bacterial colonization.
Clinical Immunology 11/2010; 138(1):97-106. · 4.05 Impact Factor
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ABSTRACT: In recent years, Staphylococcus aureus has become a common bowel colonizer in Swedish infants. We aimed to identify host factors that determine such colonization. Stool samples from 100 Italian and 100 Swedish infants were obtained on seven occasions during the first year of life and cultured quantitatively for S. aureus. In a subgroup of infants in each cohort, individual strains were identified by random amplified polymorphic DNA analysis. Colonization at each time-point was related to delivery mode, siblings in family and antibiotic treatment. In total, 66% of the Italian and 78% of the Swedish infants had S. aureus in their stools on at least one time-point (p 0.08) and 4% of Italian and 27% of Swedish infants were positive on at least six of the seven time-points investigated (p 0.0001). Most infants analysed regarding strain carriage harboured a single strain in their microbiota for several months. The S. aureus stool populations in colonized infants decreased from 10(7) to 10(4) colony-forming units/g between 1 week and 1 year of age in both cohorts. In multivariate analysis, the strongest predictor for S. aureus colonization was being born in Sweden (OR 3.4 at 1 week of age, p 0.002). Having (an) elder sibling(s) increased colonization at peak phase (OR 1.8 at 6 months, p 0.047). Antibiotic treatment was more prevalent among Italian infants and correlated negatively with S. aureus colonization at 6 months of age (OR 0.3, p 0.01). To conclude, S. aureus is a more common gut colonizer in Swedish than Italian infants, a fact that could not be attributed to feeding or delivery mode.
Clinical Microbiology and Infection 11/2010; 17(8):1209-15. · 4.54 Impact Factor
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ABSTRACT: Acute otitis media (AOM) is an inflammatory response to microbes in the middle ear, sometimes associated with rupture of the tympanic membrane. Human leukocytes produce different patterns of inflammatory mediators in vitro when stimulated with Gram-positive and Gram-negative bacteria, respectively. Here, we investigated the cytokine and prostaglandin E2 (PGE2) responses in middle ear fluids (MEFs) from children with spontaneously perforated AOM, and related the mediator levels to the presence of pathogens detected by culture (live) or PCR (live or dead). Furthermore, the in vivo cytokine pattern was compared with that induced in leukocytes stimulated by dead bacteria in vitro. MEFs with culturable pathogenic bacteria contained more interleukin (IL)-1β (median: 110 μg/L vs. <7.5 μg/L), tumour necrosis factor (TNF) (6.3 μg/L vs. <2.5 μg/L), IL-8 (410 μg/L vs. 38 μg/L) and IL-10 (0.48 μg/L vs. <0.30 μg/L) than culture-negative fluids, irrespective of PCR findings. IL-6 and PGE2 were equally abundant (69-110 μg/L) in effusions with live, dead or undetectable bacteria. Cytokine levels were unrelated to bacterial species and to the presence or absence of virus. Similar levels of TNF and IL-6 as found in the MEFs were obtained by in vitro stimulation of leukocytes, whereas 11 times more IL-1β and 3.5 times more IL-8 were produced in vivo, and 22 times more IL-10 was produced in vitro. Vigorous production of proinflammatory cytokines accompanies AOM with membrane rupture, regardless of the causative agent, but the production seems to cease rapidly once the bacteria are killed and fragmented. IL-6 and PGE2, however, remain after bacterial disintegration, and may play a role in the resolution phase.
Clinical Microbiology and Infection 10/2009; 16(9):1382-8. · 4.54 Impact Factor
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ABSTRACT: T-helper 17 (Th17) cells are characterized by their production of interleukin-17 (IL-17) and have a role in the protection against infections and in certain inflammatory diseases. Humans who lack Th17 cells are more susceptible to Staphylococcus aureus infections compared to individuals having Th17 cells. S. aureus is part of the commensal skin microflora and also colonize the infant gut. To investigate whether UV-killed S. aureus would be more capable of inducing IL-17 than other commensal bacteria, we stimulated mononuclear cells from adults, infants, and newborns with various gram-positive and gram-negative commensal bacteria. IL-17 was produced from adult memory Th17 cells after stimulation with superantigen-producing S. aureus but not nonsuperantigenic S. aureus or other common commensal gut bacteria. Cells from newborns were poor IL-17 producers after stimulation with S. aureus, whereas in some cases IL-17 was secreted from cells isolated from infants at the age of 4 and 18 months. These results suggest that superantigenic S. aureus are particularly efficient in stimulating IL-17 production and that the cytokine is produced from memory T cells.
Infection and immunity 10/2009; 78(1):381-6. · 4.21 Impact Factor
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ABSTRACT: Migration of CD4+CD25+FOXP3+ regulatory T cells (Treg) is important for suppressing immune responses in different tissues. Previous studies show that the majority of Treg at birth express gut homing receptor alpha(4)beta(7) and that only few express CCR4, while the reverse pattern is found in adults. The age at which homing receptor switch occurs in vivo is not known. In this study, we show, in a prospective study of human infants from birth to 3 years of age, that homing receptor switch from alpha(4)beta(7) to CCR4 commences between 1 1/2 and 3 years of age and that Treg at that age also had started their switch to a memory phenotype. The majority of naive Treg express alpha(4)beta(7) in infants but not in adults, while the majority of memory Treg express CCR4 both infants and adults. The homing receptor expression on Treg corresponds to their actual migration properties, because Treg from cord blood migrate foremost toward the gut-associated chemokine CCL25. CD4+FOXP3+ T cell numbers increase rapidly in the circulation during the first days of life indicating conversion to suppressive Treg from CD25(high) Treg precursors. These findings suggest that the gut is the primary site of Treg stimulation to exogenous Ags during the first 18 mo of life and that homing receptor switch toward a more extra-intestinal phenotype occurs thereafter.
The Journal of Immunology 10/2009; 183(7):4360-70. · 5.79 Impact Factor
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ABSTRACT: To examine if intake of Lactobacillus plantarum can prevent gastrointestinal side effects in antibiotic-treated patients.
Diarrhea is a common side effect of treatment with antibiotics. Some studies indicate that the risk of antibiotic-associated diarrhea can be reduced by administration of certain probiotic microorganisms.
Patients treated for infections at a university hospital infectious diseases clinic were randomized to daily intake of either a fruit drink with L. plantarum 299v (10(10) colony forming units/d) or a placebo drink, until a week after termination of antibiotic treatment. Subjects recorded the number and consistency of stools as well as gastrointestinal symptoms until up to 3 weeks after last intake of test drink. Fecal samples were collected before the first intake of test drink and after termination of antibiotic therapy and analyzed for Clostridium difficile toxin.
Clinical characteristics on admission were similar in the 2 groups. The overall risk of developing loose or watery stools was significantly lower among those receiving L. plantarum [odds ratio (OR), 0.69; 95% confidence interval (CI), 0.52-0.92; P=0.012], as was development of nausea (OR, 0.51; 95% CI, 0.30-0.85; P=0.0097). Diarrhea defined as > or =3 loose stools/24 h for > or =2 consecutive days was unaffected by the treatment (OR, 1.4; 95% CI, 0.33-6.0; P=0.86). No significant differences regarding carriage of toxin producing C. difficile were observed between the groups.
Our results indicate that intake of L. plantarum could have a preventive effect on milder gastrointestinal symptoms during treatment with antibiotics.
Journal of clinical gastroenterology 09/2009; 44(2):106-12. · 2.21 Impact Factor
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ABSTRACT: Molecular biological methods using real-time polymerase chain reaction (RT-PCR) for detection of bacterial and viral genes in different environments have been developed into assays from different commercial sources. Applied Biosystems include and support two applications with their TaqMan instrument: the "Plus/Minus" and the "Allelic Discrimination" assays. These approaches are RT-PCR based, use short primers and fluorescent-labeled TaqMan probes and include three processes: a pre-read run, a PCR-amplification run, and a post-read run. In the "Plus/Minus" assay, samples and controls (distilled water) are loaded into the instrument, which calculates a positive or a negative outcome based on differences in signals between samples and the controls. When testing the "Plus/Minus" assay for detection of usp genes encoding a uropathogenic specific protein in Escherichia coli, an inordinately high proportion of false-positive signals was observed. This was shown to be due to a serious methodological deficiency. Our observations indicate that an adequate no-template control closely matching the target samples in all aspects, including amount of DNA, is required to establish a correct threshold in the pre-read run that forms the basis for further calculations in the post-read run of the "Plus/Minus" assay.
Apmis 02/2009; 117(1):68-72. · 1.99 Impact Factor
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ABSTRACT: Secretory otitis media (SOM) is characterised by persistent fluid in the middle ear cavity, but the cause is unknown. We investigated the clinical, bacteriological and immunological effects of treatment with probiotic bacteria on SOM.
In this double-blind pilot/preliminary study, 60 children with long-standing SOM (median 6 months) who were scheduled for insertion of tympanostomy tubes were randomised to nasal spray treatment with Streptococcus sanguinis, Lactobacillus rhamnosus or placebo for 10 days before surgery. Clinical evaluation was carried out after 10 days of treatment. Middle ear fluid (MEF) was collected during surgery for quantification of cytokines and detection of bacteria by culture and polymerase chain reaction (PCR). Nasopharyngeal swabs were obtained before treatment and at surgery.
Complete or significant clinical recovery occurred in 7/19 patients treated with S sanguinis compared to 1/17 patients in the placebo group (p<0.05). In the L rhamnosus treatment group, 3/18 patients were cured or much better (p = 0.60 compared with placebo). Spray treatment did not alter the composition of the nasopharyngeal flora or the cytokine pattern observed in the nasopharynx or MEF, except for a higher level of IL-8 found in the nasopharynx of L rhamnosus treated children.
This study shows that spray treatment with S sanguinis may be effective against SOM. The mechanism for the effect remains to be investigated.
Archives of Disease in Childhood 09/2008; 94(2):92-8. · 2.88 Impact Factor
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ABSTRACT: To compare the colonization dynamics of ampicillin-resistant and ampicillin-susceptible Escherichia coli strains in the infantile intestinal microbiota.
We followed 128 infants over the first year of life with regular quantitative faecal cultures and recordings of antibiotic treatment. E. coli strains were quantified, and their resistance pattern and carriage of beta-lactamase genes (TEM, SHV and OXA), phylogenetic group (A, B1, B2 or D), virulence gene profile (fimA, papC, sfaD/E, kfiC neuB, hlyA and iutA) and time of persistence in the microbiota were determined.
Twelve percent (n = 32) of the E. coli strains were resistant to ampicillin, as they carried the bla(TEM) (84%) or bla(SHV) genes. Ampicillin-resistant strains belonged mostly to phylogenetic group D and carried pap genes (P = 0.023) significantly more often than ampicillin-susceptible strains due to a strong association between carriage of pap and bla(SHV). In 31 of 32 cases, colonization by ampicillin-resistant strains occurred in infants not previously treated with beta-lactam antibiotics. Ampicillin-resistant strains were equally capable as susceptible ones of persisting in the intestinal microbiota and did not have lower faecal population counts. Genes encoding beta-lactamases were in most cases retained during the entire colonization period.
The results suggest that ampicillin-resistant E. coli strains are not hampered in their colonizing capacity, and beta-lactamase genes, therefore, may only slowly be eliminated from the commensal E. coli strain pool.
Journal of Antimicrobial Chemotherapy 07/2008; 62(4):703-8. · 5.07 Impact Factor
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Ingegerd Adlerberth
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ABSTRACT: The establishment of the intestinal microbiota commences at birth and new bacteria establish in succession during the first years of life until an adult-type highly complex microbiota has been achieved. The first bacteria to establish in the neonatal gut are usually aerobic or facultatively anaerobic bacteria, like enterobacteria, enterococci and staphylococci. During their growth they consume oxygen and change the intestinal milieu making it suitable for the proliferation of anaerobic bacteria. Bifidobacterium, Clostridium and Bacteroides are among the first anaerobes establishing in the microbiota. As more oxygen-sensitive species establish and the complexity of the microbiota increases, the population sizes of aerobic and facultative bacteria decline. This phenomenon is thought to result from oxygen depletion, substrate competition and the accumulation of toxic metabolites. A wide range of factors influence the intestinal microbiota and its establishment, including delivery and feeding mode, antibiotic treatment, and contacts with parents, siblings, and hospital staff. Differences in colonization pattern can be observed between vaginally and sectiodelivered infants, and between infants in industrialized and developing countries, reflecting the importance of maternal microbiota and the environment as sources of colonizing bacteria. This article describes the intestinal colonization pattern in human infants, and reviews factors affecting this process.
Nestle Nutrition workshop series. Paediatric programme 02/2008; 62:13-29; discussion 29-33.
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Mei Wang,
Caroline Karlsson,
Crister Olsson, Ingegerd Adlerberth,
Agnes E Wold,
David P Strachan,
Paolo M Martricardi,
Nils Aberg,
Michael R Perkin,
Salvatore Tripodi,
Anthony R Coates,
Bill Hesselmar,
Robert Saalman,
Göran Molin,
Siv Ahrné
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ABSTRACT: 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.
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.
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.
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.
There is a reduced diversity in the early fecal microbiota of infants with atopic eczema during the first 18 months of life.
The Journal of allergy and clinical immunology 02/2008; 121(1):129-34. · 9.17 Impact Factor
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ABSTRACT: To investigate the presumed acquisition of ampicillin resistance by an Escherichia coli strain residing in the gut of an infant.
E. coli strains were quantified in faecal samples obtained at regular intervals from an infant followed from birth to 12 months of age and their resistance profiles were determined. beta-Lactamases were identified by isoelectric focusing and genes by PCR followed by DNA sequencing. Plasmids were characterized by restriction fragment analysis and Southern-blot hybridization, and tested for conjugative transfer.
The infant carried two E. coli strains, termed 29A and 29B, simultaneously in the microbiota during the first month of life. All isolates of 29A were resistant to ampicillin, whereas strain 29B, which was initially ampicillin susceptible, acquired resistance following treatment of the infant with ampicillin/amoxicillin because of urinary tract infection. Acquisition of resistance by strain 29B was associated with acquisition of a bla(TEM-1b)-encoding plasmid, pNK29, which was also present in strain 29A. Transfer of plasmid pNK29 could be replicated by conjugation from strain 29A to strain 29B in vitro. Strain 29A also adapted to ampicillin treatment by mutation of the bla(TEM-1b) promoter gene to yield a higher level of resistance.
This is an unequivocal demonstration of gene transfer between two strains co-residing in the human gut, as the donor, recipient and transconjugant strains were isolated. The results suggest the dynamic adaptation by commensal bacteria in response to antibiotic treatment may occur readily.
Journal of Antimicrobial Chemotherapy 12/2007; 60(5):1142-5. · 5.07 Impact Factor
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Ingegerd Adlerberth,
David P Strachan,
Paolo M Matricardi,
Siv Ahrné,
Lia Orfei,
Nils Aberg,
Michael R Perkin,
Salvatore Tripodi,
Bill Hesselmar,
Robert Saalman,
Anthony R Coates,
Carmen L Bonanno,
Valentina Panetta,
Agnes E Wold
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ABSTRACT: Stimulation of the immune system by gut microbes might prevent allergy development.
The present study examined the hypothesis that sensitization to food allergens and atopic eczema are influenced by the infantile intestinal colonization pattern.
Infants were recruited perinatally in Göteborg (n = 116), London (n = 108), and Rome (n = 100). Commensal bacteria were identified to the genus or species level in rectal (3 days) and quantitative stool cultures (7, 14, and 28 days and 2, 6, and 12 months of age). At 18 months of age, atopic eczema and total and food-specific IgE levels were assessed. These outcomes were modeled in relation to time to colonization with 11 bacterial groups and to ratios of strict anaerobic to facultative anaerobic bacteria and gram-positive to gram-negative bacteria at certain time points. Study center, mode of delivery, parity, and infant diet were included as covariates.
Neither atopic eczema nor food-specific IgE by 18 months of age were associated with time of acquisition of any particular bacterial group. Cesarean section delayed colonization by Escherichia coli and Bacteroides and Bifidobacterium species, giving way to, for example, Clostridium species. Lack of older siblings was associated with earlier colonization by Clostridium species and lower strict anaerobic/facultative anaerobic ratio at 12 months.
This study does not support the hypothesis that sensitization to foods or atopic eczema in European infants in early life is associated with lack of any particular culturable intestinal commensal bacteria.
The nature of the microbial stimulus required for protection from allergy remains to be identified.
Journal of Allergy and Clinical Immunology 09/2007; 120(2):343-50. · 11.00 Impact Factor
