A multiplex PCR assay was designed to amplify the Aeromonas hydrophila and A. veronii bv. sobria hemolysin and aerolysin genes. The assay was evaluated by using 121 clinical isolates and 7 reference strains of Aeromonas spp., and these were divided into five genotypes on the basis of the results of the multiplex PCR. The five genotypes were characterized as type 1 for those carrying the ahh1 ge...

A cytotoxin produced by some Helicobacter pylori strains has recently been identified. The cytotoxin induces intracellular vacuolization of cultured cells. The aim of the present study was to examine the frequency of occurrence of cytotoxin-producing strains of H. pylori from subjects with upper gastrointestinal disease including nonulcer dyspepsia, gastric and duodenal ulcer disease, gastroeso...

The vacuolating cytotoxin and the cytotoxin-associated protein, encoded by vacA and cagA, respectively, are important virulence determinants of Helicobacter pylori. Sixty-five H. pylori strains were isolated from dyspeptic patients (19 with peptic ulcer disease, 43 with chronic gastritis, and 3 with gastric cancer) and studied for differences in the vacA and cagA genes and their relationship to...

We describe two subclones of Helicobacter pylori, isolated contemporaneously from a human stomach, which differ markedly in the vacuolating cytotoxin gene, vacA, but whose near identity in sequences outside this locus implies a very recent common origin. The differences are consistent with homologous recombination with DNA from another strain and result in a changed vacA midregion and, importan...

Fecal specimens from 223 subjects were evaluated for the presence of Clostridium difficile by use of a selective medium developed in our laboratory and for the presence of C. difficile cytotoxin. C. difficile and cytotoxin were detected in 89 and 83%, respectively, of patients with antimicrobial agent-associated pseudomembranous colitis (PMC). In patients in whom PMC was not documented, C. diff...

The vacuolating cytotoxin produced by Helicobacter pylori is considered to be one virulence factor causing peptic ulceration. In this study, we examined the activity of vacuolating cytotoxin in induction of intracellular vacuolation of rabbit gastric epithelial cells (RGECs). We used culture supernatants of H. pylori as a source of vacuolating cytotoxin and quantitated cytotoxic activity by the...

There are two alleles of the vacuolating cytotoxin gene from Helicobacter pylori, which code for toxins with different cell specificities. By analyzing the phenotypes of natural and artificial chimeras between the two forms of the protein, we have delimited a short stretch of amino acids which determine the cell specificity.