The influence of properties encoded by theYersiniavirulence plasmid on adhesion ofYersinia enterocoliticato ileal brush border membrane vesicles

Characteristics of Yersinia pseudotuberculosis isolated from animals in Brazil

Strains (105) of Yersinia pseudotuberculosis isolated in Brazil between 1982 and 1990 were bio-serotyped. They were also studied for plasmid profile, autoagglutination and calcium dependence at 37 degrees C, Congo red uptake, pyrazinamidase activity, esculin hydrolysis, salicin fermentation and drug sensitivity: 95.24% were biotype 2, serogroup O:3; 2.86% were biotype 1, serogroup O:1; and 1.90% were biotype 2, non-agglutinable. Plasmids were found in 77.14% of the strains (one in each strain). There was total correlation between the presence of the virulence plasmid and autoagglutination, calcium dependence at 37 degrees C and Congo red uptake. The esculin, salicin and pyrazinamidase tests were not efficient in differentiating pathogenic from non-pathogenic Y. pseudotuberculosis isolates. All strains were highly sensitive to the drugs used. These results indicate that Y. pseudotuberculosis is a potential pathogen for humans in Brazil, especially because the bio-serogroups detected among animals are those most frequently associated with human diseases.

Use of leukodepletion filters for the removal of bacteria

Recipient exposure to allogeneic donor leukocytes can mediate a number of immunologic complications of transfusion or can transmit leukotropic viruses carried by the donor. Leukocyte depletion of cellular blood components has been shown to reduce the incidence of such complications. In recent years, prestorage leukocyte depletion by filtration has also been suggested as a means of decreasing the incidence of bacterial overgrowth in cellular blood components. This review analyzes published studies on the use of leukodepletion filters for removal of Staphylococcus epidermidis and Yersinia enterocolitica from blood. Although ineffective for removal of S. epidermidis from Platelet Concentrates, inoculation studies demonstrate removal of low levels of Y. enterocolitica from Red Cell Concentrates. Based on these studies, four possible mechanism(s) for removal of bacteria by leukodepletion filters are analyzed: phagocytosis by leukocytes during a prefiltration holding period; complement-mediated bacterial killing enhanced by filtration; adherence of bacteria to leukocyte surfaces retained within the filter; and direct removal of bacteria by the filter media. Just as multiple mechanisms appear to account for the efficiency with which these filters deplete blood of leukocytes, it is likely that more than one mechanism accounts for the experimental observation that leukocyte depletion filters can reduce overgrowth of Y. enterocolitica in stored Red Cell Concentrates.

Binding of Yersinia enterocolitica to purified, native small intestinal mucins from rabbits and humans involves interactions with the mucin carbohydrate moiety

Plasmid-bearing (but not plasmid-cured) Yersinia enterocolitica is known to bind to purified small intestinal mucins from rabbits and humans. This study examined which region(s) of the mucin molecule is important for bacterial adherence. Pronase digestion of mucin and removal of nonglycosylated or poorly glycosylated peptide regions had no effect on bacterial binding, suggesting that plasmid-bearing Y. enterocolitica interacts with mucin carbohydrate. Periodate oxidation also did not alter bacterial adherence, indicating that vicinal hydroxyl groups in the mucin sugars are not important for binding. Boiling of mucin, depolymerization by reduction of disulfide bonds, or removal of noncovalently associated lipid actually enhanced bacterial adherence, suggesting that plasmid-bearing Y. enterocolitica can interact with additional domains in the mucin molecule revealed by these treatments. These domains were destroyed by pronase digestion. In delipidated mucin (but not in reduced or boiled mucin), binding to these domains appeared to be hydrophobic since it could be prevented by treatment of bacteria with tetramethyl urea. Oligosaccharides obtained from both human and rabbit small intestinal mucins were capable of inhibiting attachment of plasmid-bearing (but not plasmid-cured) Y. enterocolitica to mucin. After removal of terminal and backbone sugar residues by treatment of mucin with trifluoromethanesulfonic acid, binding of plasmid-bearing bacteria increased significantly when N-acetylgalactosamine, either alone or with galactose attached, was revealed, indicating that core regions of the sugar side chains are involved in bacterial binding. Adherence of plasmid-cured organisms was unaffected by trifluoromethanesulfonic acid treatment of mucin. We concluded that virulent Y. enterocolitica interacts with the carbohydrate moiety of native small intestinal mucin through a plasmid-mediated process. When mucin becomes denatured, binding of the organism can increase through hydrophobic and nonhydrophobic interactions with (most likely) the mucin protein.

Adhesion of Yersinia enterocolitica to purified rabbit and human intestinal mucin

Interactions between Yersinia enterocolitica and purified intestinal mucins from rabbit and humans were investigated. Plasmid-bearing virulent organisms (but not plasmid-free nonvirulent bacteria) bound well to both mucins, suggesting that adherence was controlled by the virulence plasmid. Examination of binding to 14 different preparations of purified human intestinal mucin (8 preparations obtained from normal subjects and 6 samples from patients with cystic fibrosis) revealed no differences between normal and cystic fibrotic mucins in ability to serve as a binding substrate for virulent Y. enterocolitica. Analyses of binding curves suggested the presence of a single type of noninteracting receptor for Y. enterocolitica in both rabbit and human mucins with similar (but not necessarily identical) structures. Virulent bacteria bound to polystyrene through hydrophobic interactions that could be disrupted by treating the organisms with tetramethyl urea. In contrast, binding of plasmid-bearing Y. enterocolitica to intestinal mucin was not susceptible to tetramethyl urea and therefore does not appear to involve hydrophobic interactions. Prior incubation of organisms with mucin significantly inhibited binding to polystyrene, suggesting that mucin can mask hydrophobic adhesins on the bacterial surface. Hapten inhibition studies revealed that the monosaccharides galactose and N-acetylgalactosamine and the disaccharide lactose could markedly reduce (but not abolish) bacterial adherence to mucin but other monosaccharides and the RGD peptide had no effect on mucin binding. We conclude that virulent Y. enterocolitica is capable of interacting with the carbohydrate moiety of intestinal mucin. These interactions appear to be plasmid mediated and not hydrophobic.

Role of the Yersinia outer membrane protein YadA in adhesion to rabbit intestinal tissue and rabbit intestinal brush border membrane vesicles

The Yersinia virulence plasmid confers on strains of Yersinia pseudotuberculosis and Y. enterocolitica an adhesive potential superior to the one encoded by the chromosome alone. We have evaluated the role of the plasmid-encoded outer membrane protein YadA (formerly called Yopl) in adhesion. Insertional inactivation of the yadA gene (formerly called yopA), which encodes YadA, led to a reduction in the capacity of plasmid-carrying strains of Y. pseudotuberculosis 0:III and Y. enterocolitica 0:9 to adhere to intestinal tissue, brush border membranes and polystyrene surfaces. The adhesive characteristics of the mutants were comparable to those of their plasmid-cured counterparts. When the yadA gene from Y. pseudotuberculosis serotype 0:III or Y. enterocolitica serotype 0:3 or 0:8 was cloned into an Escherichia coli strain, increased ability to adhere to intestinal tissue, brush border membrane vesicles and polystyrene was transferred concomitantly. The introduction of the yadA gene from Y. pestis, which is unable to express YadA due to a one base pair deletion, did not change the adhesive characteristics of E. coli. Expression of YadA in the outer membrane may, therefore, make an important contribution to intestinal adherence of the two enteropathogenic members of the Yersinia species, Y. pseudotuberculosis and Y. enterocolitica.