Gwynn R. Chippendale

Role of Hpn and NixA of Helicobacter pylori in Susceptibility and Resistance to Bismuth and Other Metal Ions

Background. Helicobacter pylori produces Hpn, a 60‐amino acid, histidine‐rich protein that avidly binds nickel and zinc ions, and NixA, a high‐affinity nickel transporter in the cytoplasmic membrane. We tested the hypothesis that Hpn and NixA govern susceptibility to metal ions in H. pylori.

Adherence to Uroepithelial Cells of Providencia stuartii Isolated from the Catheterized Urinary Tract

The long-term catheterized urinary tract appears to offer a niche for Providencia stuartii, otherwise an unusual clinical isolate. P. stuartii, the most frequent and persistent isolate from the urine of 51 long-term catheterized patients, was recovered from 761 of 1230 (62%) weekly urine specimens. To test the hypothesis that prevalence of this species may be due to adherence properties of the organism, 20 selected strains from 14 patients at two nursing homes, representing six distinct serotypes and harbouring combinations of nine different plasmid species, were tested for adherence to uroepithelial cells (UEC). Optimal conditions were determined for differentiating strains on the basis of in vitro adherence to UEC. These strains, grown in nutrient broth, were incubated with UEC isolated from the urine of a healthy adult female (10(8) bacteria per 10(5) cells). Washed UEC, retained on 8 micron pore diameter filters, were transferred to slides, fixed and stained; bacteria were counted on each of 40 cells. Fourteen of the 20 strains were defined as adherent to UEC by comparison of mean adherent bacteria and percentage of uroepithelial cells with more than 10 bacteria. Adherence was compared to that of a P-fimbriated strain of Escherichia coli. It was not inhibited by 50 mM-mannose. We conclude that the majority of P. stuartii isolates are adherent to UEC in vitro and suggest that this may play a role in the persistence of this organism in the catheterized urinary tract.

In vitro adhesion of bacteria to exfoliated uroepithelial cells: criteria for quantitative analysis.

Publisher Summary This chapter discusses in vitro adhesion of bacteria to exfoliated uroepithelial cells. It is useful to measure the ability of bacterial cells to bind to epithelial cells whether the interaction is specific or nonspecific. A technique was developed to study adhesion of uropathogenic strains of Escherichia coli to exfoliated uroepithelial cells isolated from urine—although the assay was quite useful, it has now been found that a number of desirable features of other reported techniques could be incorporated into the method to simplify preparation and gain additional information. Adaptations to the assay used to measure bacterial adhesion combine features from several reports and provide ease of sample preparation and accurate evaluation of adherent bacteria. Expression of adhesion factors may be favored by a particular medium, growth temperature, pH, or degree of aeration. Conditions that favor expression of adhesins by a specific species must be determined empirically.