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Background. A retrospective study of the clinical, epidemiologic, and virologic features of norovirus gastroenteritis in 12 adult allogeneic hematopoietic stem cell transplant (HSCT) recipients. Methods. Norovirus infection was diagnosed by reverse-transcriptase polymerase chain reaction. Strains were genotyped by nucleic acid sequence of the most highly conserved region of the norovirus gene encoding the capsid S (shell) domain. Results. Ten of 12 patients presented with vomiting of short duration, but diarrhea was present in all. The median time from onset to norovirus diagnosis was 1 month (range, 0.25-6.0 months). Eleven patients were receiving immunosuppression when norovirus infection was diagnosed: 8 for graft-versus-host disease (GVHD) in an organ other than gut, 1 for previous gut GVHD, and 2 for presumed gut GVHD that proved to be norovirus gastroenteritis. Six patients required enteral or parenteral nutrition for severe weight loss. In 10 patients, diarrhea lasted a median of 3 months (range, 0.5-14 months) and virus was shed at a high level throughout. The remaining 2 patients died after 4 months of diarrhea (one died of unrelated complications, and the other died of malnutrition). The noroviruses found were GII (untyped), GII-3, GII-4, and GII-7 in 1, 1, 9, and 1 patients, respectively. Eleven of the 12 patients had acquired their infection in the community. Phylogenetic analysis of the GII-4 strains demonstrated that all differed. Conclusions. Noroviruses are a hitherto unsuspected cause of prolonged morbidity and mortality in adults after allogeneic HSCT. The use of reverse-transcriptase polymerase chain reaction to detect high viral load levels in feces distinguishes norovirus gastroenteritis from gut GVHD. [ABSTRACT FROM AUTHOR]

This study describes a method used to determine the diversity of NoVs co-circulating in the community that consisted of the analysis of a limited number of strains collected from outbreaks occurring at different times of the NoV season. The diversity of twenty NoV strains collected from outbreaks occurring at the beginning of each NoV season (September) was compared to the diversity found in the middle (December) and at the end of the season (March). The method was validated through the characterisation of greater numbers of strains at times when novel genotypes or variants were detected. A total of 864 strains from outbreaks of gastroenteritis from the 2003/04, 2004/05 and 2005/06 seasons were genotyped, with the majority of outbreaks occurring in the UK. There was a greater diversity of NoV genotypes at the beginning of two of the three seasons, 2003/04 and 2005/06, when compared to strains circulating at the end of the seasons, and GII-4 NoV strains predominated (>90%) at the end of each season. Data from this study also identified the co-circulation and differentiation of three major GII-4 variants (v2, v3, and v4). Detailed analysis of a larger number of strains throughout each season confirmed that variants emerged, became the predominant circulating strain and were ultimately replaced with another variant selected from a pool of variants. By June 2006, GII-4 v4 (Hu/NoV/Rhyl440/2005/UK) emerged as the predominant GII-4 strain, usurping the previous GII-4 v3 strain [Hu/NoV/Hunter284E/040/AU] to become the commonest co-circulating strain, in the UK in 2006. [ABSTRACT FROM AUTHOR]

Helicobacter pullorum was first isolated from the faeces and carcasses of poultry and has been associated with human gastroenteritis. The aim of this study was to examine interstrain genetic diversity within H. pullorum. Two fingerprinting techniques were used: amplified fragment length polymorphism (AFLP) and pulsed field gel electrophoretic (PFGE) analysis. The 20 strains examined were from four countries and comprised 13 human isolates and seven poultry isolates. Their identity was confirmed by a species-specific PCR assay. The human and poultry isolates had distinct genotypes and most strains showed a high degree of genetic diversity. Genotyping also indicated a clonal origin for two strains from the same poultry flock, and established a close relatedness between three chicken carcass isolates from a processing plant. It is concluded that these two genotyping techniques will provide a useful basis for future epidemiological investigations of H. pullorum in poultry, and may provide a link with its possible causal role in human gastrointestinal infections. [ABSTRACT FROM AUTHOR]

Objectives: Application of multilocus sequence typing shows that recombination is so frequent within H. pylori that each isolate appears to possess unique sequences for each housekeeping gene analysed. Even so, there is evidence that geographic separation may have resulted in distinct populations on different continents. Our aim was to explore the existence of remnant pockets of conservation by analysis of sequences of three loci in antral isolates from dyspeptic patients in geographically separated populations. Methods: Nucleotide sequences of ahpC, ureI and atpA internal fragments of about 500 bp were determined or obtained from public databases for isolates from Nigerians (8) Japanese (4), and Chinese (4). The two sets of sequences were compared and contrasted with those in our database for 124 other isolates from England and 11 other countries. Phylogenetic analyses were performed and trees constructed with BioEdit and TREECON, and analysis of single/multiple nucleotide polymorphisms (SNPs) was performed with DNASp. Results: Analysis of urel sequences showed a high degree of intra-set relatedness for isolates from the different countries although each set was well separated in the general phylogenetic tree. Similar associations were evident from analysis of ahpC data whereas linkages were more diverse on atpA data. Interestingly the Nigerian and Japanese/Chinese sets each had distictive but unique amino acid sequences derived from ahpC. This observation prompted analysis of individual polymorphisms which showed two population specific polymorphisms at a/a positions 125 and 139. Twelve other SNPs that distinguished the two sets were present in isolates from the UK and other countries. Discussion: We found evidence of population-specific polymorphisms in ahpC in isolates from remote countries. Although the frequency of these markers needs to be determined in a larger number of isolates, the findings are suggestive that conserved remnants exist despite genomic... [ABSTRACT FROM AUTHOR]