Enteroinvasive Escherichia coli has not been extensively studied for cytotoxin production. We evaluated 30 well-characterized enteroinvasive E. coli strains of all the known invasive serogroups from several geographic regions for their ability to produce Shiga-like cytotoxic activity assayed in a HeLa cell system. None of these strains produced cytotoxic activity that was neutralizable with ant...

Gnotobiotic mice died 2 days after inoculation of a cytotoxigenic Clostridium difficile strain. Protection occurred when mice were previously inoculated with a strain of Escherichia coli or Bifidobacterium bifidum. Intestinal cytotoxin production was highly reduced in the surviving mice, whereas the C. difficile population level did not decrease to a great extent.

Toxins in culture supernatants and bacterial lysates of S. dysenteriae 1 and S. flexneri were quantitated by a cytotoxicity assay and a newly developed radioimmunoassay. Cytotoxin titers paralleled toxin antigen levels. Thus, variations in cytotoxicity among shigellae probably reflect differences in toxin yield rather than specific activity (cytotoxicity per microgram of toxin antigen).

The vacuolating cytotoxin of Helicobacter pylori, VacA, enters the cytoplasm of target cells and causes vacuolar degeneration by interfering with late stages of endocytosis. By using indirect immunofluorescence and flow cytometry, we have demonstrated that VacA binds to specific high-affinity cell surface receptors and that this interaction is necessary for cell intoxication.

To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gnotobiotic piglets were colonized with either toxigenic H. pylori or a nontoxigenic isogenic mutant. Only piglets given the toxigenic strain developed toxin-neutralizing antibodies (indicating that toxin is expressed in vivo), but there was no difference in bacterial colonization, epithelial vacuolat...

Abbreviations: Egr-1, early growth response gene-1; EGFR, epidermal growth factor receptor; ERK, extracellular-regulated kinases; MAP kinases, mitogen-activated protein kinases; PAI, pathogenicity island; cag, cytotoxin associated genes; PMA, Phorbol-12myristate-13-acetate; MOI, Multiplicity of infection; GAPDH, glyceraldehyde-3phosphate dehydrogenase; PCR, polymerase chain reaction; PBS, phosp...

We investigated the presence of the gene of subtilase cytotoxin (SubAB), described in certain highly virulent verocytotoxigenic E. coli strains, in isolates from Argentina and its relation with other virulence factors. The gene subA was present in eae-negative strains mostly associated with saa, vt2 and ehxA genes.

Although Helicobacter pylori has a significant impact on the occurrence of severe clinical syndromes, its exact ways of transmission and origin have not been identified. According to the results of some previously published articles, foods with animal origins play a substantial role in the transmission of H. pylori to humans. The present investigation was carried out to study the vacuolating cy...

A 48-hour culture filtrate of Campylobacter jejuni was found to produce cytopathic effects on three human cell lines--that is, HeLa, MRC-5 and Hep-2. The cytopathic effects observed include cell rounding, loss of adherence and cell death after 24-48 h of incubation. Such morphological changes were observed with eight of the eleven strains of Campylobacter jejuni isolated from the blood/stools o...