Biomedical subjects
Publications and source records attributed to F Espersen.
Peritonitis remains the major complication of continuous ambulatory peritoneal dialysis. A review is given of the clinical, microbiological, immunological, and pathogenic aspects of this problem and new fields of research for reducing the incidence of peritonitis are suggested.
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.
Interactions between Yersinia enterocolitica and rabbit ileal mucus were examined. Strains carrying the Yersinia virulence plasmid, pYV, adhered to crude mucus but not to intestinal luminal contents that had been immobilized on polystyrene. Using an Y. enterocolitica O:9 mutant in which the yadA gene (formerly called yopA), encoding the high-molecular-weight outer membrane protein YadA (formerly called protein P1 or Yop1), had been inactivated and an Escherichia coli strain carrying the cloned yadA gene, we demonstrated that the ability to adhere to mucus correlated closely to expression of YadA. Thereafter, we evaluated possible consequences of binding between pYV-carrying Y. enterocolitica O:3 strains and constituents in the mucus layer. pYV-carrying strains were able to multiply at a high rate in mucus but not in luminal contents, and the ability to adhere to mucus could therefore facilitate bacterial colonization of the mucosa. However, we also showed in vitro that mucus acted as a barrier for a mucus-adherent, pYV-carrying Y. enterocolitica strain. Furthermore, penetration through, or preincubation with, mucus reduced subsequent adhesion of the pYV-carrying strain to brush border membrane vesicles without simultaneously causing bacterial aggregation. Preincubation with mucus also changed the bacterial surface of the same strain from hydrophobic to hydrophilic. Immunoglobulins present in mucus did not seem to be of importance for our observations. Interaction of Y. enterocolitica with intestinal mucus may thus reflect a host defense mechanism that reduces the pYV-mediated adhesion to the epithelial cell membrane, possibly by rendering the bacteria less hydrophobic.
Antibodies against Yersinia enterocolitica serotype O:3 were measured by crossed immunoelectrophoresis (XIE) using whole-cell sonic extract as antigen and by enzyme-linked immunosorbent assays (ELISAs) using either purified lipopolysaccharide or whole formalinized cells expressing virulence plasmid-encoded surface antigens (pYV+ cells). The results were compared with those obtained with the standard tube agglutination method. Sera from three groups of people were examined by using these assays. The first group consisted of healthy blood donors, the second consisted of patients with recent infection due to microorganisms other than Y. enterocolitica O:3, and the third consisted of patients with recent Y. enterocolitica O:3 infection. Sera from the last group were also obtained at regular intervals for 12 months postinfection. Results obtained with XIE and the ELISAs were in good agreement with those obtained with tube agglutination. Variation, diagnostic sensitivity, and diagnostic specificity were satisfactory for all the assays studied. However, the lipopolysaccharide ELISA was less laborious than tube agglutination and XIE and carried a somewhat greater diagnostic specificity than the pYV+ ELISA. XIE and the pYV+ ELISA, on the other hand, also had advantages. XIE enabled simultaneous examination of the individual antibody response against a wide range of chromosome-encoded antigens, and the pYV+ ELISA enabled detection of specific pYV antibodies when sera were adsorbed with formalinized pYV-cured Y. enterocolitica O:3 cells prior to the assay.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Histamine release from human basophil leukocytes was triggered by Staph. aureus, Salmonella enteritidis, non-haemolytic streptococci, or E. coli. Influenza A virus was found to enhance the mediator release and the effect was caused by synergism, since the virus did not induce release of histamine per se. This potentiating effect of the virus was seen both when the bacteria-induced histamine release was IgE-dependent (i.e. patient sensitized to the bacterium) and when the bacterium caused mediator release by a non-immunological mechanism independent of IgE (putative sugar-lectin mediated). Histamine release induced by anti-IgE and calcium ionophore or agarose-beads was also enhanced in the presence of the virus. These findings indicate that influenza A virus potentiates both IgE- and non-IgE-mediated histamine release induced by bacteria and other stimulators.
ELISAs using subclass-specific monoclonal antibodies were developed for the quantification of human IgG1, IgG2, IgG3 and IgG4 antibodies to Ps. aeruginosa. We investigated the pattern of IgG subclass antibodies against Ps. aeruginosa in serum from patients with cystic fibrosis (CF), other patients with chronic Ps. aeruginosa infection, and healthy controls. Healthy controls and patients with CF but without Ps. aeruginosa infection showed no or very low titres of antibodies against Ps. aeruginosa. In the early stage of chronic Ps. aeruginosa infection, antibody titres in all four subclasses were significantly higher than either normals or CF patients without infection. Other patients with Ps. aeruginosa infection showed the same increased level of IgG subclass antibodies as CF patients in an early stage of infection. Sixteen patients (eight in good and eight in poor clinical condition) have been followed for an average of 13 years with multiple serum samples covering the pre-infection, early and late stages of chronic infection. Patients in a poor clinical condition showed significantly higher levels of IgG3 antibodies in the first year of infection and 2 years later also had significantly higher IgG2 antibody levels. We conclude that elevated levels of IgG2 and IgG3 antibodies to Ps. aeruginosa are a sign of poor prognosis in CF.
Influenza A virus was found to enhance basophil histamine release induced by Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus sanguis, but did not per se release histamine. This potentiating effect of the virus was seen both when the bacteria-induced mediator release was IgE-dependent (i.e. patient allergic to bacterium) and when the bacterium caused histamine release by a non-immunological mechanism independent of IgE (putative sugar-lectin mediated). Also histamine release induced by other immunological and non-immunological stimuli, such as anti-IgE, calcium ionophore or agarose beads was enhanced in the presence of the virus. The potentiating effect of the virus on bacteria-induced mediator release might be of importance for the conversion from latent to manifest asthma in upper respiratory tract infections.
Alginate, a viscous polysaccharide from mucoid Pseudomonas aeruginosa, may interfere with the host defenses in patients with cystic fibrosis and chronic P. aeruginosa lung infection. The alginate concentration in the sol phase of expectorated sputum was quantitated by a biochemical method and a newly developed enzyme-linked immunosorbent assay. There was a high degree of correlation between the methods, and the concentration of alginate ranged from 4 to 101 micrograms/ml with a median of 35.5 micrograms/ml when measured by enzyme-linked immunosorbent assay. Alginate could not be detected in the bronchial secretions from patients without P. aeruginosa infection. In vitro investigation of alginate did not show any activation of the alternative pathway of complement, as determined by a hemolytic kinetic assay and by testing for neutrophil chemotaxis. At a high concentration, P. aeruginosa alginate caused a slight activation of the classical pathway of complement. Alginate did not cause neutrophil chemotaxis by itself but was able to reduce the neutrophil chemotactic response to N-formylmethionylleucylphenylalanine and for zymosan-activated serum. P. aeruginosa and seaweed alginates were able to prime neutrophils for increased N-formylmethionylleucylphenylalanine-induced neutrophil oxidative burst, as determined by chemiluminescence. Because of its ability to prevent attraction of neutrophils to the site of infection, lack of complement activation, and ability to enhance neutrophil oxidative burst, alginate from P. aeruginosa may contribute to the persistence and pathogenesis of chronic P. aeruginosa infection in cystic fibrosis.
Patients with cystic fibrosis have a high prevalence of mucoid, alginate-producing Pseudomonas aeruginosa that causes chronic infection of the mucosal surface of the lungs. We developed enzyme-linked immunosorbent assays (ELISAs) for determination in serum of immunoglobulin A (IgA) and IgG antibodies to alginate purified from P. aeruginosa and an ELISA for detection of IgA antibodies to a polyvalent P. aeruginosa standard antigen. Absorption experiments indicated that the assays were antigen and antibody specific and had analytical variations that ranged from 7 to 19%. Serum samples from 207 patients with cystic fibrosis, 100 healthy children, and 94 healthy adults were examined. The patients responded to P. aeruginosa infection with early IgA and IgG antibody responses that were significantly higher than in controls and noncolonized patients. Analysis of paired serum samples showed that infected patients had an increase in specific IgG and IgA antibodies that was significantly higher than in noncolonized patients. The serological data were analyzed for correlation with clinical condition; poor lung function was significantly associated with increased levels of IgA and IgG antibodies to P. aeruginosa alginate and to the standard antigen and with a relative excess of IgA antibodies to the standard antigen compared with IgA antibodies to P. aeruginosa alginate. The assays showed high predictive values if positive, but a negative test did not exclude infection, and the ELISAs should not be used for diagnostic purposes. Mucoid strains were present initially in the sputa of 28 of 54 infected patients with paired serum samples. These patients had a significant increase in anti-alginate antibodies, but it was not different from the increase seen in patients infected only with nonmucoid strains. Therefore, alginate may also be produced in vivo by nonmucoid P. aeruginosa. The study showed that early formation of IgA and IgG antibodies to P. aeruginosa alginate did not prevent development of chronic infection and that P. aeruginosa-specific IgA antibodies correlate with poor lung function.
An amino oxide and three quaternary ammonium salts were investigated for antimicrobial activity. All compounds had low MIC against gram positive bacteria. Despite high MIC the ammonium salts gave good killing of Pseudomonas aeruginosa in time kill experiments. These quaternary ammonium salts may be useful for disinfection as they are easily broken down in the environment.
The ability of peptidoglycan from Staphylococcus epidermidis and Staphylococcus aureus to generate in human serum chemoattractant for peripheral blood neutrophils was studied. It was shown that PG from the two bacteria was able to induce chemotactic activity in normal human serum. Sonication of PG was required to generate this activity. Very little or no activity was generated in heat-treated or C5-deficient human serum by PG, indicating that PG treatment of serum resulted in generation of chemoattractants by activation of complement. Kinetics studies employing C2-deficient or MgEGTA-chelated serum revealed that S. epidermidis induced chemotactic activity by activating the alternative complement pathway. The alternative complement activation induced by S. epidermidis occurred rapidly and was completed after 15 min, whereas S. aureus activated the alternative pathway much more slowly, with activation reaching a maximum at 60 min. The rapid activation of the alternative complement pathway by S. epidermidis PG may partly explain why this bacterium does not normally cause infections in healthy individuals.
The influence of plasmid-associated cell surface structures on the ability of Yersinia enterocolitica to bind to ileal brush border membrane vesicles (BBVs) was investigated. Rabbit or human BBVs were immobilized on polystyrene microtiter plates and adhesion of radiolabeled cells of Y. enterocolitica was determined. Strains of pathogenic serotypes carrying the Yersinia virulence plasmid (pYV+), as well as their isogenic plasmid cured derivatives (pYV-), adhered to immobilized BBVs, but adhesion of pYV+ organisms was markedly greater than that of pYV- ones. Strains belonging to non-pathogenic serotypes did not adhere significantly. The pYV+ strain Ye0301P+ did not express specific adhesion to glycolipids, nor was adhesion to BBVs reduced in the presence of various monosaccharides. Proteolytic digestion of surface structures on strain Ye0301P+ markedly reduced adhesion. pYV+ strains also demonstrated greater adhesion to a non-biological surface (polystyrene) and showed a higher degree of hydrophobicity than pYV- organisms as evaluated in a two-phase partitioning system. It is therefore likely that the plasmid-associated adhesion of Y. enterocolitica is promoted by one or more outer membrane proteins, that confer hydrophobicity to the bacterial surface.
In assays to determine adherence of Yersinia enterocolitica, virulence plasmid-containing (pYV+) strains and strains of their plasmid-cured (pYV-) derivatives adhered equally efficiently to HeLa cells and fetal intestinal epithelial INT 407 cells. Non-pathogenic strains of Y. enterocolitica did not adhere. In contrast, pYV+ strains adhered more efficiently to rabbit and human intestine than did pYV(-)-strains, as evaluated by an in vitro assay, measuring adhesion of radiolabeled bacteria to disks of intestinal tissue. Thus, even if pathogenic strains of Y. enterocolitica are able to adhere to cultured epithelial cell lines and intestinal tissue by means of chromosome-encoded properties alone, properties encoded by the pYV plasmid significantly enhance and contribute to adhesion to intestinal tissue.
The adherence of radiolabeled staphylococci to silicone catheters was investigated in vitro. Staphylococcus aureus and Staphylococcus epidermidis strains bound to the same extent to the catheters. Also, S. epidermidis strains isolated from patients with plastic-related infections showed binding similar to that of other S. epidermidis strains. By preincubation of catheters the influence of purified staphylococcal cell surface components on the binding was evaluated. The most potent inhibitors of the binding of S. aureus were the two surface proteins, clumping factor and protein A, and the cytoplasmic membrane. Surface proteins and the cell membrane of S. epidermidis also blocked the binding. Only protein-containing surface proteins inhibited the binding. The production of slime correlated with the degree of S. epidermidis binding. Human plasma and serum, as well as purified albumin and IgG, inhibited the binding of both staphylococcal species. Fibrinogen, and to a certain extent fibronectin, inhibited the binding of S. epidermidis, while both these purified plasma proteins enhanced the binding of S. aureus.
Explore the source record for details and available documents.