The genus Helicobacter has expanded at a rapid pace and no fewer than 31 species have been named since the proposal of the genus in 1989. Of these 31 species, 22 are principally associated with extragastric niches and there is increasing interest in the role of these taxa in diseases of humans and animals. Substantial evidence attests to certain species playing a role in the pathogenesis of enteric, hepatic and biliary disorders and some taxa demonstrate zoonotic potential. The importance of extragastric Helicobacters is likely to be an important topic for research in the near future. Here, important papers published in the field this last year are reviewed.
"Nowadays, it comprises 32 formally named species and several putative Helicobacter spp., which are currently under investigation (http://www.bacterio.cict.fr/). The DNA of a number of Helicobacter spp., which was isolated from the stomach, intestinal tract, and liver of a variety of animals, was also detected in human bile and liver samples (On et al., 2002; O'Rourke et al., 2001). Helicobacter-like DNA has been found in the liver of patients with chronic liver disease (CLD) (Nilsson et al., 1999, 2000; Stalke et al., 2005), cholangiocarcinoma, and hepatocellular carcinoma (HCC) (Al-Soud et al., 2008; Avenaud et al., 2000; Nilsson et al., 2001; Ponzetto et al., 2000). "
[Show abstract][Hide abstract] ABSTRACT: Many Helicobacter spp. were isolated from the stomach, intestinal tract, and liver of different animals and humans. The association between Helicobacter spp. and hepatobiliary diseases, including hepatocellular carcinoma, was thoroughly examined, indicating a potential role of the bacteria in the progression toward cancer. In our work, we screened 97 liver biopsies from patients with chronic liver diseases for the presence of Helicobacter spp. DNA. With the use of genus-specific polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and subsequent sequencing, we found that the majority of Helicobacter spp. DNA detected was similar to Helicobacter rodentium DNA (71%). The DNA of other detected Helicobacter spp. was similar to Helicobacter pylori DNA. This is the first indication of H. rodentium-like DNA presence in human liver tissue. We also conclude that PCR-DGGE is a useful screening method for assigning species designation and heterogeneity.
"H. pylori is another important human pathogen and is responsible for peptic ulcer disease and gastritis . H. hepaticus is an extragastric Helicobacter species that may be involved in hepatobiliary disorders . W. succinogenes is considered to be a non-pathogenic, host-associated organism that was first isolated from bovine rumen fluid  "
[Show abstract][Hide abstract] ABSTRACT: The introduction of novel genes by horizontal gene transfer (HGT) is considered an alternative mechanism for genetic adaptation, leading to diversification and speciation. The goal of this study was to determine which genes that are present in all sequenced epsilon-proteobacterial genomes were acquired by HGT. In our approach we used BLAST analysis to reduce the number of genes that subsequently needed to be analysed using more in-depth phylogenetic methods, including neighbour-joining and maximum likelihood. Among the 991 core genes found in all five completed epsilon-proteobacterial genome sequences, we identified 30 genes that were probably acquired by HGT. It is proposed that these genes displaced an ancestral core gene with a similar function. Although it was not possible to identify putative donor taxa for all acquired genes, it was clear that genes were acquired from a wide range of Bacteria, including Spirochaetes, Firmicutes, Actinobacteria, mycoplasmas and several subdivisions of the Proteobacteria. We did not observe HGT from Archaea to the epsilon-Proteobacteria. The majority of acquired genes were operational genes involved in transport, metabolism, signal transduction and energy production and conversion.
Research in Microbiology 06/2005; 156(5-6):738-47. DOI:10.1016/j.resmic.2005.01.016 · 2.71 Impact Factor
"Taxa such as Helicobacter acinonychis, Helicobacter mustelae, Helicobacter bizzozeronii, Helicobacter felis and 'Candidatus H. suis' are associated with similar gastric diseases in various animal hosts, such as cheetahs, ferrets, cats, dogs and pigs (Fox, 1997). Animals used for biomedical research are commonly colonized by intestinal Helicobacter species (Fox, 1997; Goto et al., 2000; Shen et al., 2001) and there is an increasing body of evidence that shows that enteric and hepatic disease in humans and animals may be caused by taxa that include Helicobacter canadensis, Helicobacter hepaticus and Helicobacter bilis (On et al., 2002). Infections that involve multiple Helicobacter species are also known (Jalava et al., 1998). "
[Show abstract][Hide abstract] ABSTRACT: Helicobacter species are fastidious bacterial pathogens that are difficult to culture by standard methods. A PCR-denaturing gradient gel electrophoresis (PCR-DGGE) technique for detection and identification of different Helicobacter species was developed and evaluated. The method involves PCR detection of Helicobacter DNA by genus-specific primers that target 16S rDNA and subsequent differentiation of Helicobacter PCR products by use of DGGE. Strains are identified by comparing mobilities of unknown samples to those determined for reference strains; sequence analysis can also be performed on purified amplicons. Sixteen DGGE profiles were derived from 44 type and reference strains of 20 Helicobacter species, indicating the potential of this approach for resolving infection of a single host by multiple Helicobacter species. Some more highly related species were not differentiated whereas in highly heterogeneous species, sequence divergence was observed and more than one PCR-DGGE profile was obtained. Application of the PCR-DGGE method to DNA extracted from faeces of zoo animals revealed the presence of Helicobacter DNA in 13 of 16 samples; a correlation was seen between the mobility of PCR products in DGGE analysis and DNA sequencing. In combination, this indicated that zoo animals are colonized by a wide range of different Helicobacter species; seven animals appeared to be colonized by multiple Helicobacter species. By this approach, presumptive identifications were made of Helicobacter bilis and Helicobacter hepaticus in a Nile crocodile, Helicobacter cinaedi in a baboon and a red panda, and Helicobacter felis in a wolf and a Taiwan beauty snake. All of these PCR products ( approximately 400 bp) showed 100 % sequence similarity to 16S rDNA sequences of the mentioned species. These results demonstrate the potential of PCR-DGGE-based analysis for identification of Helicobacter species in complex ecosystems, such as the gastrointestinal tract, and could contribute to a better understanding of the ecology of helicobacters and other pathogens with a complex aetiology.
Journal of Medical Microbiology 10/2003; 52(Pt 9):765-71. DOI:10.1099/jmm.0.05314-0 · 2.25 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.