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PubMed2005

[Analysis of the probiotic Bifidobacterium and Lactobacillus community in child intestinal flora].

To investigate the distribution of child intestinal flora and the composition of its key probiotics community, study on intestinal flora of 21 Chinese children (age 2 - 5) was conducted, which included bacteria isolation and counting, 16S rDNA sequencing and homology analysis. For identification of the key probiotics such as Bifidobacterium and Lactobacillus in children feces at the species level, the specific primers Im26/Im3 and L159/L677 for PCR amplification of partial 16S rDNA were used. The results show that the composition of child intestinal flora is was relatively stable and almost same to the intestinal flora of the youth (age 20 - 25). Culture-based approaches show that the key probiotic community in feces at the species level was highly different in composition and numbers from individual to individual. B. longum and B. pseudocatenulatum, which are detected at levels of 10(7) CFU/g (wet) in samples and the detection rates are 90.48% and 85.71% respectively, are believed to be major bifidobacterial species in child intestinal microbiota. In addition, B. adolescentis, B. bifidum, B. infantis and B. thermacidophium have also been found. L. mucosae, L. fermentum, L. salivarius, L. ruminis, L. gasseri and L. plantarum are isolated from the stools. L. mucosae (3.68 log10 CFU/g (wet), detection rate 71.43%) and L. fermentum (3.97 log10 CFU/g (wet), detection rate 52.38%) are two dominant species of Lactobacillus. Study on Chinese child intestinal flora, especially on the compositions and numbers of key probiotics in the feces will be very helpful to the development of effective probiotics in future.

Bifidobacterium↗

PubMed2002

Molecular monitoring of succession of bacterial communities in human neonates.

The establishment of bacterial communities in two healthy babies was examined for more than the first 10 months of life by monitoring 16S ribosomal DNA (rDNA) diversity in fecal samples by PCR and denaturing gradient gel electrophoresis (DGGE) and by analyzing the sequences of the major ribotypes. DGGE profiles of the dominant populations in the intestines of the infants were obtained by analyzing daily or weekly fecal samples. After delivery, the germfree infant gastrointestinal tracts were rapidly colonized, and the succession of bacteria in each ecosystem was monitored. During the first few days of life the profiles were simple, but they became more complex as the bacterial diversity increased with time in both babies. Clone libraries of amplified 16S rDNA fragments from baby feces were constructed, and these libraries allowed identification of the bacterial types by comparative DNA sequence analysis; the bacteria identified included members of the genera Bifidobacterium, Ruminococcus, Enterococcus, Clostridium, and Enterobacter: Species most closely related to the genera Bifidobacterium and Ruminococcus in particular dominated the intestinal microbiota based on the stability over time and the numbers, as estimated by the intensities of the bands. However, 19 of the 34 cloned rDNA sequences exhibited less than 97% identity with sequences of known bacteria or cloned sequences in databases. This study showed that using PCR-DGGE and 16S rDNA sequence analysis together resulted in a dynamic description of bacterial colonization in the infant intestinal ecosystem and allowed visualization of bacteria that are difficult to cultivate or to detect by other methods.

Bacteria, Anaerobic↗

PubMed1987

Susceptibility to five antimicrobial agents of strains of the Bacteroides fragilis group isolated in Brazil.

The in vitro activity of metronidazole, chloramphenicol, clindamycin, cefoxitin, and carbenicillin was tested by an agar dilution method against 228 strains of the Bacteroides fragilis group isolated from human intestinal microbiota during 1981 and 1982. All the strains were susceptible to metronidazole. Resistance rates for chloramphenicol, clindamycin, cefoxitin, and carbenicillin were 2, 37, 21, and 13%, respectively.

Anti-Bacterial Agents↗

PubMed1999

Functionality of probiotics and intestinal lactobacilli: light in the intestinal tract tunnel.

The commercial interest in functional foods that contain live microorganisms, also termed probiotics, is paralleled by increasing scientific attention to their functionality in the digestive tract. Most studies are focused on intestinal Lactobacillus species, which are part of the natural gastro-intestinal microbiota, and include analysis of colonisation factors and other interactions with the host, the design of novel or improved strains with specific health benefits, and the application of sophisticated molecular tools to determine their fate and activity in situ.

Genetic Techniques↗

PubMed2006

Beyond diversity: functional microbiomics of the human colon.

Molecular tools have revealed wide microbial diversity in the human alimentary tract. Most intestinal microorganisms have not been cultured and the in situ functions of distinct groups of the intestinal microbiota are largely unknown but pivotal to understanding the role of these microorganisms in health and disease. Promising strategies to gain more insight into the functionality of the complex microbial communities in the human alimentary tract, including fermentation processes in the colon, are discussed. These research approaches could provide a basis for the definition of a healthy gut based on key properties of microbial functionality. This will also enable the development of direct nutritional strategies for intestinal disease prevention and health promotion.

Biodiversity↗

PubMed2006

Clostridium difficile and Clostridium perfringens species detected in infant faecal microbiota using 16S rRNA targeted probes.

Clostridium perfringens and Clostridium difficile are pathogenic clostridia potentially associated with gastrointestinal infections and allergy in infants. To enable the molecular detection and quantification of these species in the infant gut, two 16S rRNA oligonucleotide probes were developed: Cdif198 for C. difficile and Cperf191 for C. perfringens. We defined the probes in silico using the RDP sequence database. The probes were then validated using FISH combined with flow cytometry and a collection of target and non-target strains, and faecal samples inoculated with dilutions of C. difficile and C. perfringens strains. These new probes were used to assess the composition of the intestinal microbiota of 33 infants of 1.5 to 18.5 months of age, associated with a panel of 8 probes targeting the predominant faecal bacterial groups of humans. The probes designed allowed detection and quantification of the relative proportions of C. difficile (0.5+/-1.0%) and C. perfringens (2.1+/-2.3%) in the microbiota of infants.

Clostridioides difficile↗

PubMed1991

Effects of roxithromycin on fecal bacteria in human volunteers and resistance to colonization in gnotobiotic mice.

The ecological impact of roxithromycin given orally at 300 mg/day on the intestinal floras in six human volunteers was studied. The resulting fecal concentrations of active roxithromycin were in the range of 100 to 200 micrograms/g of feces. Consecutive modifications in the composition of the fecal floras were limited to a decrease in counts of total members of the family Enterobacteriaceae. The rest of the intestinal floras, including the predominant anaerobic floras, changed little. No overgrowth of Pseudomonas aeruginosa, staphylococci, fungi, or highly erythromycin-resistant strains of the family Enterobacteriaceae was observed. The strains of Enterobacteriaceae and of anaerobes isolated during treatment were not markedly more resistant to roxithromycin than those isolated before treatment started. Changes in intestinal resistance to colonization by exogenous microorganisms in gnotobiotic mice inoculated with human fecal flora were studied and were also found to be minimal. The impact of oral roxithromycin on the intestinal microbiota appears to be weaker than that previously observed with oral erythromycin, perhaps because the concentrations of roxithromycin in the feces were lower than those previously found for erythromycin.

Administration, Oral↗

PubMed2006

The role of probiotics and prebiotics in pediatric practice.

OBJECTIVE: To review the effects of probiotics and prebiotics in clinical pediatric practice. SOURCES: MEDLINE was searched, especially for articles that addressed their practical application, in the form of reviews, clinical trials and meta-analyses. Articles that had already been analyzed by the authors were also included. SUMMARY OF THE FINDINGS: Scientific literature on probiotics and prebiotics has remarkably increased in the last 10 years. Their mechanisms of action have been experimentally investigated. Studies indicate that probiotics can act by competing with pathogens, modifying the intestinal environment by reduction in pH, as a result of fermentation products, interacting and modulating local and systemic inflammatory and immune response, among others. Clinical trials and meta-analyses show that probiotics seem to contribute towards the prevention of acute diarrhea and of antibiotic-associated diarrhea, in addition to shortening the duration of acute diarrhea. However, the data are inconsistent and there are no studies confirming their efficacy in terms of cost-benefit ratio. Preliminary studies show that probiotics in early life can reduce the occurrence of atopic dermatitis. The addition of prebiotics to infant formulas is associated with the change in the profile of the intestinal microbiota compared to infants fed milk formulas without prebiotics. CONCLUSIONS: Evidence indicates that new studies should be carried out about probiotics, prebiotics and symbiotics. The specific clinical effects that each probiotic or prebiotic may cause must be considered.

Acute Disease↗

PubMed2006

Molecular monitoring of the intestinal flora by denaturing high performance liquid chromatography.

Gut flora analysis is hampered by the complexity of the intestinal microbiota and by inherent limitations of culture-based approaches. Therefore, culture-independent molecular methods based upon 16S rRNA gene analysis were applied successfully for the analysis of complex microbial communities. However, generally accepted and validated profiling methods such as denaturing and temperature gradient gel electrophoresis (DGGE/TGGE) are still laborious and time consuming. Thus, we adapted the separation of amplified bacterial 16S rRNA gene fragments by denaturing high performance liquid chromatography (DHPLC) using the WAVE Microbial Analysis System as a rapid and convenient means to display complex intestinal bacterial communities and to monitor changes in the gut flora. The separation of 16S rRNA gene fragments amplified from reference strains representing main gut bacterial populations and from human stool samples revealed that DHPLC analysis effectively detects bacterial groups predominant in the human gut flora. The investigation of faecal samples from hospitalized patients before, during and after antibiotic therapy showed that PCR-based DHPLC can be used to monitor gut flora changes. Results from DHPLC analysis were comparable with DGGE profiles generated from the same samples, demonstrating that the adapted DHPLC protocol is well suited for the analysis of complex microbial communities.

Chromatography, High Pressure Liquid↗

PubMed1994

Effect of fiber source on short-chain fatty acid production and on the growth and toxin production by Clostridium difficile.

BACKGROUND: Fermentable fiber promotes the growth of resident gut microbes, which modify the environment of the gastrointestinal tract and thus prevent colonization by Clostridium difficile. METHODS: An in vitro system with pigs as fecal inoculum donors was used to estimate fiber fermentability and changes in intestinal microbiota. RESULTS: Acetate and propionate production (mumol/mg substrate fermented/day) was greatest for gum arabic (1013.4 and 704.1, respectively); butyrate production was greatest for xylo-oligosaccharide (345.6). Growth of total anaerobes and clostridia was greatest for gum arabic (21.2 and 16.2 x 10(8) counts/ml, respectively) and xylo-oligosaccharides (21.0 and 19.6 x 10(8) respectively); growth of acidogenic bacteria was greatest with fructo-oligosaccharide (6.7 x 10(8) counts/ml). No culturable counts of C. difficile were obtained, nor was toxin A detected. CONCLUSIONS: Fermentable fibers support the growth of indigenous intestinal bacteria, particularly acidogenic bacteria, and yield large amounts of short-chain fatty acids with decreased gut pH. These factors contribute to the prevention of growth and toxin elaboration by C. difficile.

Animals↗

PubMed2001

Microbial biota of the human intestine: a tribute to some pioneering scientists.

Research on the indigenous intestinal microbiota of man was initiated well before the end of the 19th Century. The work continued at a slow but steady pace throughout the first half of the 20th Century. Findings from the effort had little impact on medicine and other aspects of human biology, however, until the 6th decade of the 20th Century. During that decade, research in the area was begun by eight groups of investigators, each of which was led by one or two senior scientists with great experimental talent, creativity and foresight. Their findings added new dimension to knowledge of the microbiota and initiated an explosion of interest in research in the field that has continued to the present day. The research of the groups during the 1960's is described in this review as a tribute to the senior scientists who had such critical impact on this important field of study.

Animals↗

PubMed2005

Intestinal innate immunity: how does it relate to the pathogenesis of necrotizing enterocolitis.

The pathogenesis of necrotizing enterocolitis (NEC) is poorly understood, but appears to be multifactorial and highly associated with immaturity of the gastrointestinal tract, colonization of the intestinal microbiota, and immature innate immune system. The goal of this review is to provide an overview of some of these risk factors and how they might lead to the genesis of NEC. A better understanding of these factors should help us prevent and treat this devastating disease.

Enterocolitis, Necrotizing↗

PubMed2005

Occurrence and activity of human intestinal bacteria involved in the conversion of dietary lignans.

The human intestinal microbiota is necessary for the production of enterolignans from the dietary lignan secoisolariciresinol diglucoside (SDG). However, little is known about the bacteria that contribute to SDG conversion. Therefore, we aimed at describing the occurrence and activity of SDG metabolising bacteria. The data showed differences in conversion efficiency between SDG deglycosylating species, but SDG was completely deglycosylated within 20 h by five of six strains. The strain Clostridium sp. SDG-Mt85-3Db showed the highest initial rate of SDG deglycosylation. Furthermore, we found that Bacteroides distasonis and B. fragilis made up 0.5% and 3.3% of total faecal bacteria, respectively. However, Clostridium sp. SDG-Mt85-3Db was detected within the dominant microbiota of only two out of 20 faecal samples. Bacteria involved in the demethylation step of SDG conversion also demethylated a variety of compounds other than SDG. In particular, Peptostreptococcus productus demethylated the lignans pinoresinol, lariciresinol and matairesinol. Finally, Eggerthella lenta catalysed the reduction of pinoresinol and lariciresinol to secoisolariciresinol.

Bacteroides↗

PubMed1999

Selection and design of probiotics.

Over the past 5 years the probiotic field has exploded with a number of new cultures, each purported to elicit a variety of benefits. Lists of functional characteristics and benefits, in vivo, are now commonplace to any presentation on probiotics. Scientifically established health claims remain among the highest priorities to companies who seek to establish solid health benefits that will promote their particular probiotic. The scientific community faces a greater challenge and must objectively seek cause and effect relationships for many potential and currently investigated probiotic species and strain combinations. Rational selection and design of probiotics remains an important challenge and will require a platform of basic information about the physiology and genetics of candidate strains relevant to their intestinal roles, functional activities, and interactions with other resident microflora. In this context, genetic characterization of probiotic cultures is essential to unequivocally define their contributions to the intestinal microbiota and ultimately identify the genotypes that control any unique and beneficial properties. Strain selection and differentiation, based on the genetic complement and programming of a candidate probiotic, then becomes feasible. Looking ahead, it will be vital to the development of this exploding field to correlate important characteristics in probiotics with known genotypes and regulatory controls that are likely to affect functionality and beneficial outcomes, in vivo.

Base Sequence↗

PubMed1971

Caffeic acid metabolism by bacteria of the human gastrointestinal tract.

The metabolism of caffeic acid, previously shown to be carried out by the intestinal microbiota of man and experimental animals, has now been examined in a number of bacteria isolated from human feces. It has been found that of the 12 organisms isolated none has the ability to catalyze more than one reaction of the series leading from caffeic acid to either m-hydroxyphenylpropionic acid or 4-ethylcatechol.

Anaerobiosis↗

PubMed2006

Functional foods and paediatric gastro-intestinal health and disease.

The application of molecular methods to gastro-intestinal diseases is giving insight into the way in which the resident intestinal microbiota interacts with the mucosal immune system. Using traditional culture techniques, the importance of mucosally-associated bacterial biofilms in maintaining mucosal integrity has been demonstrated in ways previously impossible. Changes in the balance of organisms at initiation of and during disease provide a rationale for interventions with functional foods which facilitate re-establishment of the homeostasis of healthy gut.

Bacteria↗

PubMedDate not supplied

Evidences of gentamicin resistance amplification in Klebsiella pneumoniae isolated from faeces of hospitalized newborns.

The intestinal microbiota, a barrier to the establishment of pathogenic bacteria, is also an important reservoir of opportunistic pathogens. It plays a key role in the process of resistance-genes dissemination, commonly carried by specialized genetic elements, like plasmids, phages, and conjugative transposons. We obtained from strains of enterobacteria, isolated from faeces of newborns in a university hospital nursery, indication of phenotypical gentamicin resistance amplification (frequencies of 10(-3) to 10(-5), compatible with transposition frequencies). Southern blotting assays showed strong hybridization signals for both plasmidial and chromosomal regions in DNA extracted from variants selected at high gentamicin concentrations, using as a probe a labeled cloned insert containing aminoglycoside modifying enzyme (AME) gene sequence originated from a plasmid of a Klebsiella pneumoniae strain previously isolated in the same hospital. Further, we found indications of inactivation to other resistance genes in variants selected under similar conditions, as well as, indications of co-amplification of other AME markers (amikacin). Since the intestinal environment is a scenario of selective processes due to the therapeutic and prophylactic use of antimicrobial agents, the processes of amplification of low level antimicrobial resistance (not usually detected or sought by common methods used for antibiotic resistance surveillance) might compromise the effectiveness of antibiotic chemotherapy.

Drug Resistance, Microbial↗

PubMed1999

Petfood applications of inulin and oligofructose.

Published data on intestinal microbiota of dogs and cats are limited but suggest the presence of a complex and diverse colonic bacterial population (34 genera including 129 species) the majority of which are anaerobes. During the colonic fermentation of endogenous and undigested amino acids, several putrefactive compounds (i.e., ammonia, aliphatic amines, indoles, phenols and volatile sulfur-containing compounds) are produced and are responsible for the malodor of dog and cat feces. These fecal odor components also have been implicated as causes of colorectal cancer; therefore, dietary manipulation of gut microbiota towards a potentially more remedial community (Bifidobacterium and Lactobacillus) is gaining more attention. The health benefits derived from dietary supplementation of prebiotics (e.g., oligofructose and inulin) have been documented in humans. However, little is known of a potentially similar role in companion animals. Feeding another prebiotic (i.e., lactosucrose) to dogs or cats is reported to increase the numbers of bifidobacteria and decrease the numbers of pathogens and the concentration of fecal odor components. In our laboratory, oligofructose supplementation numerically decreased the concentrations of ammonia and amines and increased the numbers of bifidobacteria in dog feces.

Animal Feed↗