Search

A new co-agglutination assay for the identification of Pseudomonas aeruginosa from culture was developed and evaluated. A total of 232 P. aeruginosa isolates, and 36 oxidase-positive, Gram-negative clinical isolates were tested. The sensitivity of the assay was 96%, and the specificity was 91.9%. The assay took <15 min to perform.

Over the course of seven pandemics, Vibrio cholerae serotypes have varied. In 1992 the appearance of a new serotype, O139 Bengal, began the eighth cholera pandemic. Several new O139 antigens have been identified, yet a common V. cholerae antigen has not been described. In this study, a monoclonal antibody specific against an 18.7-kDa outer membrane antigen reacted in dotblot analysis with 292 epidemiologically diverse V. cholerae isolates including O1, non-O1, and O139 serotypes. Serum collected from volunteers experimentally challenged with V. cholerae O139, and rabbit antisera to V. cholerae O1, were reactive with the 18.7-kDa antigen by Western immunoblot. This is the first report that the 18.7-kDa antigen is present in V. cholerae O139.

Vaccination of female rabbits with cholera protective antigen (CPA) protected their F1 progeny from lethal challenge with Vibrio cholerae. Protection was determined by the choleragenic score and survival rates. Serum and milk IgG, IgM, IgA titres to CPA, cholera toxin, and LPS were determined. At 8 and 20 weeks post-immunization, mothers' milk, sera, and infants' sera showed elevated CPA-specific IgG and IgA, and infants were protected. Mothers' serum and milk antibody remained elevated for 36 weeks. At 26 weeks, mothers were re-bred, but their progeny were swapped and cross-fed. Infants born to the placebo-vaccinated mothers and nursed by CPA-immune nannies were partially protected from challenge. Infants born to CPA-immune mothers and cross-fed by the placebo-vaccinated nannies were less protected. CPA stimulated both transplacental and milk antibody, but passive immunity was primarily milk-derived. A 36-week booster vaccine stimulated an anamnestic serological response that did not provide protection equivalent to the original vaccine. CPA provided partial protective immunity to the milk-fed infant rabbits that suggests that CPA may be important in the development of a cholera vaccine.

An 18-kDa protein that occurs in Vibrio cholerae has been described as an in vivo and low-iron regulated outer membrane antigen. Monoclonal antibodies which recognized this antigen were protective as passive vaccines in the infant rabbit model of cholera disease. In this study, those monoclonal antibodies were used in three immunological assays for surveillance of various bacteria for the 18-kDa antigen. ELISA, and Western blot assays gave variable results with bacteria or outer membrane preparations. The biodot assay was the most sensitive test, detecting the 18-kDa antigen in 29 of 29 V. cholerae strains, independent of biotype or serotype. A few other Gram-negative bacteria and V. parahaemolyticus reacted weakly with our antibodies and antiserum.

We prepared a murine monoclonal antibody that recognized the Helicobacter pylori urease. Monoclonal antibody, U2, reacted with purified native urease in enzyme linked immunosorbent assay but it did not react in Western immunoblot analysis. Urease was immunoprecipitated with U2 bound to Staphylococcus aureus protein A, followed by elution and visualization by sodium dodecyl-sulfate polyacrylamide gel electrophoresis. The species and strain specificity of U2 were determined by biodot reaction with H. pylori, H. mustelae, Campylobacter spp., and other gram-negative bacteria. Monoclonal antibody, U2, was used for an indirect immunofluorescent stain of formalin fixed gastric biopsies from patients with H. pylori gastritis. The immunofluorescent stain showed spiral and coccoid forms of H. pylori within the gastric mucosa. U2 was specific for H. pylori and did not react with other tested bacteria. These findings suggest that antibody U2 might be of diagnostic value for specific immunofluorescence detection of H. pylori.

We prepared an IgG1 murine monoclonal antibody, PS2, that recognized the 8-kDa outer membrane lipoprotein I of Pseudomonas aeruginosa. The biodot-immunoblot technique was used to test 470 bacterial isolates for their reactivity with MAb PS2. PS2 recognized 298 of 300 P. aeruginosa clinical isolates for a sensitivity of 99.3%. PS2 reacted with all Fisher-Devlin immunotype and International Antigenic Type P. aeruginosa strains. Forty-seven isolates of other Pseudomonas species were tested and only three P. cepacia reacted. PS2 did not react with 118 of 123 other gram-negative isolates, but reacted weakly with 3 of 17 Enterobacter aerogenes, 1 of 11 Eschericia coli and 1 of 2 Proteus vulgaris. The specificity of PS2 for P. aeruginosa was 95%.

The ability of microorganisms that would like to live in or on mammalian hosts to acquire iron is a critical determinant of the host-parasite interaction. Despite the abundance of iron, its availability to microbes is restricted by the iron-binding and transport systems of the host. The successful commensal or pathogen therefore must express effective systems to compete for its iron. The acquisition of iron is thus essential, although not sufficient, for virulence. This review examines host and microbial iron-acquisition and transport mechanisms in an attempt to stimulate the reader's interest in potential "soft spots" that may be exploited prophylactically and therapeutically.

Primary cultures of neonatal rat cardiac muscle cells incorporated radioiron from both [55Fe]transferrin and 59FeCl3 (added simultaneously). To evaluate the effect of iron chelators on such uptake, deferri chelators were added 6 hr after addition of the radioiron sources. The microbial chelator agrobactin was significantly more effective than the drug defoxamine in reduction of 55Fe uptake from [55Fe]transferrin; both chelators halted 59Fe3+ uptake. Agrobactin may have potential in chelation therpay for iron-overload disease. Certain other microbial chelators lowered radioiron uptake from either [55Fe]transferrin of 59FeCl3. These chelators should be useful inhibitors for studies of animal cell iron uptake and intracellular iron flow.