Article

Phenotypic and genotypic analyses of clinical Fusobacterium nucleatum and Fusobacterium periodonticum isolates from the human gut.

Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
Anaerobe (Impact Factor: 2.36). 01/2009; 14(6):301-9. DOI: 10.1016/j.anaerobe.2008.12.003
Source: PubMed

ABSTRACT Fusobacterium nucleatum is a Gram-negative anaerobic rod that is part of the normal human microflora, and has also been associated with various infections. Bacterial strains belonging to the species are typically heterogeneous in both phenotype and genotype, which can hinder their identification in a clinical setting. The majority of F. nucleatum isolates originate from oral sites, however the species is also a resident of the human gastrointestinal tract. The aim of this study was to compare F. nucleatum isolates from human intestinal biopsy samples to try and determine whether isolates from this site are divergent from oral isolates. We used a variety of phenotypic and genotypic markers to compare 21 F. nucleatum and Fusobacterium periodonticum isolates from the GI tract to oral isolates and recognized type strains in order to study heterogeneity within this set. 16S rDNA and rpoB gene sequence analysis allowed us to build phylogenetic trees that consistently placed isolates into distinct clusters. 16S rDNA copy number analyses using Denaturing Gradient Gel Electrophoresis (DGGE) demonstrated potential for use as a method to examine clonality amongst species. Phenotypic analyses gave variable results that were generally unhelpful in distinguishing between phylogenetic clusters. Our results suggest that a) F. periodonticum isolates are not restricted to the oral niche; b) phenotypic classification is not sufficient to subspeciate isolates; c) heterogeneity within the species is extensive but constrained; and d) F. nucleatum isolates from the gut tend to identify with the animalis subspecies.

0 Followers
 · 
86 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: We explored the use of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) for identification of F. nucleatum subspecies. MALDI-TOF MS spectra of five F. nucleatum subspecies (animalis, fusiforme, nucleatum, polymorphum, and vincentii) were analyzed and divided into four distinct clusters including subsp. animalis, nucleatum, polymorphum, and fusiforme/vincentii. MALDI-TOF MS with the modified SARAMIS database further correctly identified 28 of 34 F. nucleatum clinical isolates to subspecies level. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Journal of Clinical Microbiology 02/2015; 53(4):JCM.00239-15. DOI:10.1128/JCM.00239-15 · 4.23 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Fusobacterium nucleatum, a common Gram-negative anaerobe prevalent in the oral cavity, possesses the ability to colonize the amniotic cavity and the fetus. However, F. nucleatum may also be part of the vaginal microbiota from where it could reach the amniotic tissues. Due to the heterogeneity of F. nucleatum, consisting of five subspecies, analysis at the subspecies/strain level is desirable to determine its precise origin. The aims of this study were: (i) to evaluate the use of the 16S-23S rRNA gene intergenic transcribed spacer (ITS) region as a tool to differentiate subspecies of F. nucleatum, and (ii) to design a simplified technique based on the ITS to determine the origin of F. nucleatum strains associated with adverse pregnancy outcomes. Amplified fragments of the 16S-23S rRNA gene ITS region corresponding to the five subspecies of F. nucleatum were subjected to cloning and sequencing to characterize the different ribosomal operons of the subspecies. Distinctive length and sequence patterns with potential to be used for identification of the subspecies/strain were identified. These were used to evaluate the origin of F. nucleatum identified in neonatal gastric aspirates (swallowed amniotic fluid) by sequence comparisons with the respective oral and vaginal maternal samples. A simplified technique using a strain-specific primer in a more sensitive nested PCR was subsequently developed to analyse ten paired neonatal maternal samples. Analysing the variable fragment of the ITS region allowed the identification of F. nucleatum subsp. polymorphum from an oral origin as potentially being involved in neonatal infections. Using a strain-specific primer, the F. nucleatum subsp. polymorphum strain was detected in both neonatal gastric aspirates and maternal oral samples in cases of preterm birth from mothers presenting with localized periodontal pockets. Interestingly, the same strain was not present in the vaginal sample of any case investigated. The 16S-23S rRNA gene ITS can be a useful tool to determine the origin of F nucleatum. The results of this study strongly indicate that F. nucleatum subsp. polymorphum of oral origin could be involved with pregnancy complications.
    Journal of Medical Microbiology 12/2012; 62(Pt_1):133-144. DOI:10.1099/jmm.0.049452-0 · 2.27 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The gut microbiota plays an essential role in regulating intestinal homeostasis through its capacity to modulate various biological activities ranging from barrier, immunity and metabolic function. Not surprisingly, microbial dysbiosis is associated with numerous intestinal disorders including inflammatory bowel diseases (IBD) and colorectal cancer (CRC). In this piece, we will review recent evidence that gut microbial dysbiosis can influence intestinal disease, including colitis and CRC. We will discuss the biological events implicated in the development of microbial dysbiosis and the emergence of CRC-associated microorganisms, focusing on E.coli and F. nucleatum. Finally, the mechanisms by which E.coli and F. nucleatum exert potentially carcinogenic effects on the host will be reviewed.
    Immunology Letters 06/2014; 162(2). DOI:10.1016/j.imlet.2014.05.014 · 2.37 Impact Factor