FN3 protein fragment containing two type III fibronectin domains from B. longum GT15 binds to human tumor necrosis factor alpha in vitro

Most species of the genus Bifidobacterium contain the gene cluster PFNA, which is presumably involved in the species-specific communication between bacteria and their hosts. The gene cluster PFNA consists of five genes including fn3, which codes for a protein containing two fibronectin type III domains. Each fibronectin domain contains sites similar to cytokine-binding sites of human receptors. Based on this finding we assumed that this protein would bind specifically to human cytokines in vitro. We cloned a fragment of the fn3 gene (1503 bp; 501 aa) containing two fibronectin domains, from the strain B. longum subsp. longum GT15. After cloning the fragment into the expression vector pET16b and expressing it in E. coli, the protein product was purified to a homogenous state for further analysis. Using the immunoferment method, we tested the purified fragment's ability to bind the following human cytokines: IL-1β, IL-6, IL-10, TNFα. We developed a sandwich ELISA system to detect any specific interactions between the purified protein and any of the studied cytokines. We found that the purified protein fragment only binds to TNFα.

Alloscardovia omnicolens emerging presence in premature rupture of membranes

Alloscardovia omnicolens is a recently-reported microorganism with unknown pathogenic implications. It has been isolated in various clinical localizations but not in the endocervix. We isolated A. omnicolens in an endocervical sample from a 31-yr-old patient with preterm premature rupture of membranes (PPROM) in week 33+3 of pregnancy. The main risk of PPROM is prematurity and the possibility of developing infectious chorioamnionitis, which can be lethal for the mother and newborn. This is the first report of an association between A. omnicolens and PPROM, although its pathogenic role has not yet been elucidated.

Are probiotics safe? Bifidobacterium bacteremia in a child with severe heart failure

Although few cases of bacteremia or sepsis caused by probiotics have been reported, it is important to consider their pathogenic potential, especially in some categories of patients. We report a case of Bifidobacterium spp bacteremia in a child with heart disease, undergoing probiotic supplementation to prevent antibiotic-associated diarrhea.

The Amount of Bifidobacterium Genus in Colorectal Carcinoma Tissue in Relation to Tumor Characteristics and Clinical Outcome

Evidence indicates a complex link between microbiota, tumor characteristics, and host immunity in the tumor microenvironment. In experimental studies, bifidobacteria appear to modulate intestinal epithelial cell differentiation. Accumulating evidence suggests that bifidobacteria may enhance the antitumor immunity and efficacy of immunotherapy. We hypothesized that the amount of bifidobacteria in colorectal carcinoma tissue might be associated with tumor differentiation and higher immune response to colorectal cancer. Using a molecular pathologic epidemiology database of 1313 rectal and colon cancers, we measured the amount of Bifidobacterium DNA in carcinoma tissue by a quantitative PCR assay. The multivariable regression model was used to adjust for potential confounders, including microsatellite instability status, CpG island methylator phenotype, long-interspersed nucleotide element-1 methylation, and KRAS, BRAF, and PIK3CA mutations. Intratumor bifidobacteria were detected in 393 cases (30%). The amount of bifidobacteria was associated with the extent of signet ring cells (P = 0.002). Compared with Bifidobacterium-negative cases, multivariable odd ratios for the extent of signet ring cells were 1.29 (95% CI, 0.74-2.24) for Bifidobacterium-low cases and 1.87 (95% CI, 1.16-3.02) for Bifidobacterium-high cases (Ptrend = 0.01). The association between intratumor bifidobacteria and signet ring cells suggests a possible role of bifidobacteria in determining distinct tumor characteristics or as an indicator of dysfunctional mucosal barrier in colorectal cancer.

Bifidobacterium--friend or foe? A case of urinary tract infection with Bifidobacterium species

Bifidobacterium-a commensal of the human intestine is considered non-pathogenic and has been advocated as a probiotic due to its potential beneficial effects. However, there have been case reports implicating bifidobacteria as pathogenic agents in a variety of different infectious conditions. We discuss here one such case of a complicated urinary tract infection associated with Bifidobacterium spp.

Metascardovia criceti Gen. Nov., Sp. Nov., from hamster dental plaque

A novel microorganism, Metascardovia criceti gen. nov., sp. nov., was isolated from dental plaque of golden hamsters fed with a high-carbohydrate diet. The three isolated strains, OMB104, OMB105, and OMB107, were Gram-positive, facultative anaerobic rods that lacked catalase activity. Analyses of the partial 16S rRNA and heat-shock protein 60 (HSP60) gene sequences of these isolates indicated that they belonged to the family Bifidobacteriaceae. However, in contrast to Bifidobacterium, one of the genera under this family, these isolates grew under aerobic conditions, and the DNA G + C contents were lower (53 mol%) than those of Bifidobacterium. On the basis of phylogenetic analyses using phenotypic characterization, and partial 16S rRNA and HSP60 gene sequences data, we propose a novel taxa, Metascardovia criceti for OMB105(T) (type strain=JCM 13493(T)=DSM 17774(T)) for this newly described isolate.

Classification of a moderately oxygen-tolerant isolate from baby faeces as Bifidobacterium thermophilum

Background

Bifidobacteria are found at varying prevalence in human microbiota and seem to play an important role in the human gastrointestinal tract (GIT). Bifidobacteria are highly adapted to the human GIT which is reflected in the genome sequence of a Bifidobacterim longum isolate. The competitiveness against other bacteria is not fully understood yet but may be related to the production of antimicrobial compounds such as bacteriocins. In a previous study, 34 Bifidobacterium isolates have been isolated from baby faeces among which six showed proteinaceous antilisterial activity against Listeria monocytogenes. In this study, one of these isolates, RBL67, was further identified and characterized.

Results

Bifidobacterium isolate RBL67 was classified and characterized using a polyphasic approach. RBL67 was classified as Bifidobacterium thermophilum based on phenotypic and DNA-DNA hybridization characteristics, although 16S rDNA analyses and partial groEL sequences showed higher homology with B. thermacidophilum subsp. porcinum and B. thermacidophilum subsp. thermacidophilum, respectively. RBL67 was moderately oxygen-tolerant and was able to grow at pH 4 and at a temperature of 47°C.

Conclusion

In order to assign RBL67 to a species, a polyphasic approach was used. This resulted in the classification of RBL67 as a Bifidobacterium thermophilum strain. To our knowledge, this is the first report about B. thermophilum isolated from baby faeces since the B. thermophilum strains were related to ruminants and swine faeces before. B. thermophilum was previously only isolated from animal sources and was therefore suggested to be used as differential species between animal and human contamination. Our findings may disapprove this suggestion and further studies are now conducted to determine whether B. thermophilum is distributed broader in human faeces. Furthermore, the postulated differentiation between human and animal strains by growth above 45°C is no longer valid since B. thermophilum is able to grow at 47°C. In our study, 16S rDNA and partial groEL sequence analysis were not able to clearly assign RBL67 to a species and were contradictory. Our study suggests that partial groEL sequences may not be reliable as a single tool for species differentiation.

Effect of a fermented milk containing Bifidobacterium animalis DN-173 010 on the health-related quality of life and symptoms in irritable bowel syndrome in adults in primary care: a multicentre, randomized, double-blind, controlled trial

BACKGROUND

Health-related quality of life (HRQoL) has been rarely evaluated as a primary endpoint in the assessment of the effect of probiotics on the irritable bowel syndrome (IBS).

AIM

To study the effects of fermented milk containing Bifidobacterium animalis DN-173 010 and yoghurt strains on the IBS in a multicentre, double-blind, controlled trial.

METHODS

A total of 274 primary care adults with constipation-predominant IBS (Rome II) were randomized to consume for 6 weeks either the test fermented milk or a heat-treated yoghurt (control). HRQoL and digestive symptoms were assessed after 3 and 6 weeks on an intention-to-treat population of 267 subjects.

RESULTS

The HRQoL discomfort score, the primary endpoint, improved (P < 0.001) in both groups at weeks 3 and 6. The responder rate for the HRQoL discomfort score was higher (65.2 vs. 47.7%, P < 0.005), as was the decrease in bloating score [0.56 +/- (s.d.)1.01 vs. 0.31 +/- 0.87, P = 0.03], at week 3 in the test vs. the control group. In those subjects with <3 stools/week, stool frequency increased (P < 0.001) over 6 weeks in the test vs. control group.

CONCLUSIONS

This study suggests a beneficial effect of a probiotic food on discomfort HRQoL score and bloating in constipation-predominant IBS, and on stool frequency in subjects with <3 stools/week.

Conditions of bifidobacterial colonization in preterm infants: a prospective analysis

BACKGROUND

Premature birth results in a delayed and abnormal qualitative pattern of gut colonization. This abnormal pattern is thought to affect intestinal development and contribute to a higher risk of gastrointestinal infectious diseases such as neonatal necrotizing enterocolitis (NEC). In particular, bifidobacteria are thought to play a major role. We therefore studied bifidobacterial colonization in preterm infants during the first month of life.

PATIENTS AND METHODS

Fecal samples were prospectively analyzed in 52 infants born at a gestational age ranging from 30 to 35 weeks fed with a preterm formula alone and, in 18, with their mother's milk. Fecal samples were collected twice per week during the hospital stay. Bifidobacterial colonization was analyzed with culture and a molecular method.

RESULTS

Bifidobacterial colonization occurred in 18 infants at a median age of 11 days, always greater than the corrected mean gestational age of 35.4 weeks (SD, 0.9) and greater than 34 weeks for 16 of 18. Colonization by bifidobacteria was affected by neither birthweight nor mode of delivery nor antibiotics given to the mother or infant. In contrast, birth gestational age had a significant impact on colonization by bifidobacteria (P < 0.05), which always occurred in children born at a birth gestational age greater than 32.9 weeks (P < 0.05).

CONCLUSIONS

Birth gestational age seems to act as a major determinant of bifidobacterial colonization in the premature infant, suggesting the role of gut maturation, a finding that should probably be taken into account in manipulations of the gut flora aimed at reducing NEC.

Tetracycline resistance mediated by tet(W), tet(M), and tet(O) genes of Bifidobacterium isolates from humans

MICs of tetracyclines were determined for 86 human Bifidobacterium isolates and three environmental strains. The tet(O) gene was found to be absent in these isolates. tet(W) and tet(M) were found in 26 and 7%, respectively, of the Bifidobacterium isolates, and one isolate contained both genes. Chromosomal DNA hybridization showed that there was one chromosomal copy of tet(W) and/or tet(M).

Antimicrobial susceptibility of bifidobacteria

OBJECTIVES

The aim of our study was to analyse the antibiotic susceptibility of various strains of Bifidobacterium spp. to a wide range of antimicrobial agents.

METHODS

Fifty strains belonging to eight species of bifidobacteria, isolated from humans, animals or probiotic products, were tested for susceptibility to 30 antibiotics by disc diffusion on Brucella agar supplemented with 5% laked sheep blood and vitamin K1 (1 mg/L). MICs of nine anti-anaerobe agents, including three new molecules (telithromycin, linezolid and gatifloxacin), were determined using the reference agar-dilution method.

RESULTS

All strains of bifidobacteria, whatever the species, were sensitive to penicillins: penicillin G, amoxicillin (MIC(50) 0.06 mg/L), piperacillin, ticarcillin, imipenem and usually anti-Gram-positive antibiotics (macrolides, clindamycin, pristinamycin, vancomycin and teicoplanin). Susceptibility to cefalothin and cefotetan was variable. Most isolates (70%) were resistant to fusidic acid. As expected, high resistance rates were observed for aminoglycosides. Metronidazole, an agent known for its anti-anaerobe activity, was ineffective against 38% of the strains. The newly commercialized molecules, telithromycin, linezolid and gatifloxacin, were active with MIC(50)S of 1 mg/L. The only variation in susceptibility observed among the different species concerned Bifidobacterium breve, which appeared to be generally more resistant. Potentially acquired resistance was only observed against tetracycline and minocycline, in 14% of the strains.

CONCLUSIONS

With regard to a general concern about the safety of probiotics, such as potential transferability of resistance determinants, bifidobacteria, with their low natural and acquired resistance to 30 antibiotics, appear risk-free.

[Intestinal microflora in workers of harmful industry]

Prolonged work in industry under unhealthy working conditions leads to disturbances in the normal intestinal microflora in employees. The content of bifidobacteria decreases simultaneously with an increase in the amount of opportunistic microorganisms. The degree of disturbances in intestinal microbiocenosis correlates with the length of service.

Multiplex PCR using 16S rRNA gene-targeted primers for the identification of bifidobacteria from human origin

Three multiplex polymerase chain reactions (PCRs) targeted on Bifidobacterium and related species were designed to identify human species. The selected primers yielded amplified products of various sizes, each specific for a species. Three to four pairs were gathered in one PCR reaction and their specificity under multiplex conditions was confirmed using DNA from 26 reference strains. Using this technique on unidentified faecal strains, B. bifidum, B. longum and B. breve species were commonly recovered in infants while B. adolescentis, B. catenulatum/B. pseudocatenulatum continuum and B. longum species were predominant in adults. Thus, a single PCR can provide the assignment of a strain to one these species, reducing the number of PCR reactions and hands-on time for the identification of human isolates of bifidobacteria. Moreover, this technique is also applicable for the in situ detection of bifidobacteria in DNA extracts from human stools.

Species specific identification of nine human Bifidobacterium spp. in feces

Based on the 16S rDNA sequences, species specific primers were designed for the rapid identification by DNA amplification of nine human Bifidobacterium spp., namely B. adolescentis, B. angulatum, B. bifidum, B. breve, B. catenulatum, B. dentium, B. infantis, B. longum, B. pseudocatenulatum. B. lactis currently included in dairy products was added to the series. The primers were designed to target different positions of the 16S rDNA, allowing the simultaneous identification of these ten species of Bifidobacterium using two mixtures of primers. The identification procedure described in this paper was validated by establishing a correlation with an AluI restriction pattern of the different full length amplified 16S rDNA. This multiple primer DNA amplification technique was applied for the identification of pure colonies of Bifidobacterium spp. or directly from total bacteria recovered from human fecal samples. The technique was shown to be useful to detect dominant species and, when primers were used in separate reactions, underrepresented species could be identified as well.