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- Nilsson, Ingrid, et al.
(author)
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Helicobacter ganmani infection associated with a spontaneous outbreak of inflammatory bowel-like disease in an IL-10-deficient mouse colony
- 2008
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In: Scandinavian Journal of Laboratory Animal Science. - 0901-3393. ; 35:1, s. 13-24
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Journal article (peer-reviewed)abstract
- Background: A breeding colony of IL-10 deficient B6.129P2-Il10(tmICgn/J) mice, kept under conventional conditions, developed an inflammatory bowel-like disease (IBD) with rectal prolapse and blood tinged diarrhoea. No clinical signs of disease were observed at the time of arrival to our animal house. These animals were originally planned to serve as a negative control group in an experimental infection study with Helicobacter species to investigate colonization of the murine gut. Results: A spiral-shaped, Gram-negative bacterium was isolated from the breeding mice colony. In a first group of six animals, tissue specimens from the liver, small and large intestines, faeces and blood, were analysed by culture, PCR-denaturing gradient gel electrophoresis (PCR-DGGE), species-specific PCR assays and DNA-sequencing, histology and serology. Helicobacter ganmani, but no other Helicobacter species, was isolated from the liver, small bowel, caecum, colon and faeces. We found inflammation in caeca, colon and livers, most pronounced in the caecal areas of culture positive mice with a severe typhlitis with cystic dilatation of glandular structures and irregular crypt architecture. Some animals showed a pronounced colitis with mucosal and sub-mucosal inflammatory infiltrates. Other animals displayed large lymphoid infiltrates in the livers and hepatitis. Tissue samples and sera from 18 additional animals from the same breeding colony were analysed by the same methods, except for culture. H. ganmani was identified by PCR in most tissue samples of the 18 additional animals as well. Sero-conversion to H. ganmani correlated well with histopathological changes. Conclusions: Our findings emphasize the importance of using Helicobacter-free animals to develop murine models of chronic hepatitis and colitis.
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| 2. |
- Taneera, Jalal, et al.
(author)
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Influence of activated charcoal, porcine gastric mucin and beta-cyclodextrin on the morphology and growth of intestinal and gastric Helicobacter spp.
- 2002
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In: Microbiology. - 1465-2080. ; 148:3, s. 677-684
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Journal article (peer-reviewed)abstract
- Bile-tolerant Helicobacter spp. are emerging human and animal pathogens. However, due to their fastidious nature, which requires nutrient-rich complex media to grow, infection with these bacteria may be underestimated. The accumulation of toxic metabolites in cultures may be one of the main obstacles for successful culture of these organisms. The present study examined various potential growth-enhancing substances for Helicobacter spp. and, furthermore, how they may affect spiral to coccoid conversion. Five Helicobacter spp. were cultured on agar and in broth media supplemented with activated charcoal, beta-cyclodextrin, or porcine gastric mucin. Growth was determined by estimating the numbers of colony-forming units and colony diameter, as well as bacterial cell mass. Coccoid transformation was estimated every 24 h by both Gram and acridine-orange staining. Activated charcoal was superior in supporting growth and increased cell mass on agar and in broth media. beta-Cyclodextrin delayed spiral to coccoid conversion by Helicobacter pylori and Helicobacter canis, whereas activated charcoal delayed the conversion to coccoid forms of Helicobacter hepaticus and Helicobacter bilis. The progression to coccoid forms by Helicobacter pullorum on agar media was not influenced by any growth supplement. The spiral to coccoid conversion was more rapid in broth media than on agar media. The growth enhancement observed is probably related to the capacity of activated charcoal to remove toxic compounds in culture media.
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| 3. |
- Abu Al-Soud, Waleed, et al.
(author)
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Assessment of PCR-DGGE for the identification of diverse Helicobacter species, and application to faecal samples from zoo animals to determine Helicobacter prevalence.
- 2003
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 52:9, s. 765-771
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Journal article (peer-reviewed)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 (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.
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| 8. |
- Asrat, D, et al.
(author)
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Prevalence of Helicobacter pylori infection among adult dyspeptic patients in Ethiopia
- 2004
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In: Annals of Tropical Medicine and Parasitology. - : Informa UK Limited. - 1364-8594 .- 0003-4983. ; 98:2, s. 181-189
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Journal article (peer-reviewed)abstract
- In developing countries such as Ethiopia, where chronic gastritis and peptic-ulcer disease are the most common endoscopic findings, it is important to study the association between Helicobacter pylori infection and gastroduodenal diseases. Both invasive and non-invasive diagnostic methods were therefore used to investigate 300, consecutive, adult patients with dyspepsia, from the gastrointestinal clinic of Tikur Anbassa University Hospital, Addis Ababa. The apparent overall prevalence of H. pylori infection varied according to the detection method employed. Culture revealed H. pylori in only 69%, of the patients but this pathogen appeared more common when rapid urease tests (71%), PCR-denaturating gradient gel electrophoresis (91%), histopathology (81%), silver staining (75%) or stool-antigen tests (81%) were employed. Antibodies to H. pylori were detected, both by enzyme immuno-assay (EIA) and immunoblotting, in approximately 80%, of the patients, whether the antigens used were of a reference strain or from a local isolate of H. pylon. When some of the EIA-positive and EIA-negative sera were cross-absorbed with antigens of Campylobacter jejuni and re-tested by EIA, the H. pylori-positive sera remained positive and the negative sera remained negative. Dyspeptic patients in Ethiopia, like most of those previously observed elsewhere in Africa, are often infected with H. pylon. It is important that the management of these patients should not be hampered by the misinterpretation of the African epidemiology of this pathogen.
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| 9. |
- Asrat, Daniel, et al.
(author)
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Prevalence of Helicobacter pylori vacA and cagA genotypes in Ethiopian dyspeptic patients
- 2004
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In: Journal of Clinical Microbiology. - 1098-660X. ; 42:6, s. 2682-2684
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Journal article (peer-reviewed)abstract
- A total of 300 gastric biopsy samples and 50 Helicobacter pylori isolates were collected from Ethiopian adult dyspeptic patients. The vacA and cagA genes were detected in 90 and 79% of biopsy specimens, respectively, and in 100 and 87% of clinical isolates, respectively. Both genes were detected in 84% of the gastric biopsy samples and in 87% of the clinical isolates. Among vacA genotypes, the s1/m1 genotype was the most common in gastric biopsy samples (48%). The vacA and cagA positive H. pylori strains were detected to a higher degree in patients with chronic active gastritis (71%) than patients with other histopathological findings (29%) (P < 0.05).
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| 10. |
- Bielawski, Krzysztof Plotr, et al.
(author)
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Determination of lamivudine-resistant variants of hepatitis B virus by denaturing gradient gel electrophoresis: A novel approach to monitoring drug resistance
- 2008
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In: Medical Science Monitor. - 1643-3750. ; 14:5, s. 281-285
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Journal article (peer-reviewed)abstract
- Background: A DGGE-based assay for hepatitis B virus (HBV) drug-resistance monitoring was designed and checked for feasibility. It detects mutations within the YMDD motif related to lamivudine resistance. Material/Methods: The YMDD motif of HBV polymerase was amplified by the set of primers designed in this study. DGGE analysis of the amplicons was performed on 9% polyacrylamide gels containing a 20-40% gradient of urea plus formamide and electrophoresis was performed. DNA sequencing was performed using a standard protocol. Results: Based on the DGGE pattern of previously sequenced HBV variants, a reference ladder consisting of bands was constructed within and near the YMDD motif of HBV with excellent resolution. The genotypes of all the fragments included in the ladder were confirmed by sequencing after DGGE analysis. The flexibility of DGGE was demonstrated by the ability to add more bands to the migration ladder when new variants were discovered during the analysis of patient specimens. Clinical samples from HBV-infected patients were also used to demonstrate the performance of this approach. Conclusions: This preliminary feasibility study of HBV drug-resistance monitoring by means of DGGE shows the potential advantage of this approach for low-cost screening for viral drug resistance in clinical settings. The presented example can be extended to detect other mutations related to drug resistance in the HBV genome as well as other viruses.
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