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Biomedical subjects

J Dankert

Publications and source records attributed to J Dankert.

At least 217 records · Page 12Linked to original sources
PubMed1992

Molecular epidemiology of Haemophilus influenzae type b in the Gambia.

One hundred two invasive and 64 noninvasive isolates of Haemophilus influenzae were collected in the course of a 2-year prospective field study on the epidemiology of H. influenzae meningitis in The Gambia. The isolates were serotyped, biotyped, and subtyped by outer membrane protein (OMP) profile analysis (OMP subtyping). H. influenzae meningitis was found to be caused by serotype b (95%). In invasive disease, serotype a, although present in the throat of healthy children, caused only occasionally (5.9%) disease. The distribution of biotypes of H. influenzae appeared to be very similar to that found outside The Gambia. A distinct pattern of OMP subtypes, different from other parts of the world, is prevalent in H. influenzae type b (Hib) in The Gambia. OMP subtypes 2, 4, 5, 8, and 9 were observed to be predominant. These subtypes, except subtype 2, have not been described. L subtypes (subtypes 2, 4, and 8) were associated with invasive disease, whereas non-L subtypes (subtypes 5 and 9) were found more often in healthy carriers (P less than 0.001). A significant difference in geographical distribution was found in subtypes of noninvasive Hib strains (P less than 0.05). We conclude that in The Gambia H. influenzae invasive disease is caused mainly by type b strains with a limited number of OMP subtypes, which are different from the subtypes found elsewhere in the world. These data are important for the surveillance of Hib disease in developing countries and are baseline data for a Hib polyribosyl-ribitolphosphate-conjugated vaccine trial in The Gambia. Alternative Hib OMP vaccines should include a set of representative OMPs.

Bacterial Capsules↗
PubMed1992

Haemophilus influenzae is frequently detected with monoclonal antibody 8BD9 in sputum samples from patients with cystic fibrosis.

To determine the frequency of Haemophilus influenzae in sputum from patients with cystic fibrosis (CF), 477 sputum samples obtained from 86 CF patients were analyzed by standard culture and by the in situ immunoperoxidase staining technique with monoclonal antibody 8BD9. H. influenzae was isolated from 109 sputum samples (23%) from 45 patients (52%) and detected by immunoperoxidase staining in 175 sputum samples (37%) obtained from 63 patients (73%). The results of this study demonstrate the frequent presence of H. influenzae in sputum samples from CF patients.

Antibodies, Monoclonal↗
PubMed1992

Growth of uropathogenic Escherichia coli strains at solid surfaces.

The adhesion and growth of two catheter-associated (O2K2 and O83K?) and two non catheter-associated (O111K58 and O157K-) uropathogenic Escherichia coli strains on glass, poly(methyl methacrylate) (PMMA), a negatively charged copolymer of MMA and methacrylic acid (MAA) and a positively charged copolymer of MMA and trimethylaminoethyl methacrylate chloride (TMAEMA-Cl) were studied. The solid surfaces were placed in a parallel plate perfusion system. After preadhesion of the bacteria onto the surfaces, growth was initiated by perfusing the system with MacConkey broth. Growth was measured by counting adherent bacteria as a function of time. Bacterial strains were characterized by means of water contact angle, microbial adhesion to hydrocarbon (MATH), anion exchange resin retention (ARR) and zeta potential measurements. Solid surfaces were characterized by means of water contact angle and zeta potential measurements. The catheter-associated strains had significantly higher water contact angles, zeta potentials and ARR values than the non catheter-associated strains. Non catheter-associated strains did not grow at the surfaces used. Catheter-associated strains did not grow at the positively charged surface but exhibited growth at the other surfaces. Strains grew more rapidly at surfaces with a relatively high negative zeta potential and a low water contact angle than at surfaces with a relatively low negative zeta potential and a high water contact angle. The growth of strain O2K2 on glass was significantly reduced when urine instead of MacConkey broth was used as perfusion medium.

Anion Exchange Resins↗
PubMed1991

[A tuberculosis project in Ecuador].

OBJECTIVE: Determination of the frequency of pulmonary tuberculosis in an Indian community in Ecuador among symptomatic patients and contacts of patients with tuberculosis. Pulmonary tuberculosis was defined as the presence of acid fast rods in sputum. SETTING: Pontificia Universidad Catolica del Ecuador, Quito, Ecuador. DESIGN: Sputum samples were collected with the aid of an educational drama. About 5000 persons were informed on tuberculosis by this performance. The sputum samples from 241 persons were examined for presence of acid-fast rods with a direct Ziehl-Neelsen (ZN) stain and a ZN stain after concentration of the sputum. If ZN stain was negative, the sputum was cultured on Löwenstein-Jensen medium or on Coletsos medium. The Löwenstein-Jensen medium was past the expiration date. RESULTS: Bacteriological examination of the sputum samples from 241 patients and controls brought to light 65 (26.9%) individuals with acid-fast rods in the sputum. Forty per cent of the affected patients were between the ages of 20 and 34. Investigation of 82 contact persons revealed 19 (23.2%) positive cases. The results of culturing of the sputum samples were disappointing: only 6 of 152 (3.9%) samples showed growth of acid-fast rods. CONCLUSIONS: The frequency of pulmonary tuberculosis (as defined by the presence of acid fast rods in sputum) is high in the community investigated, much higher than the official data on the prevalence of tuberculosis indicate. It is important to investigate contacts of patients with pulmonary tuberculosis to trace a source and to trace new cases.

Adolescent↗
PubMed1991

[The relationship between predisposing factors in liver abscesses and the causative bacteria].

In order to assess the correlation between bacteria isolated from liver abscesses and factors predisposing to liver abscesses, a retrospective study of clinical and bacteriological data on 21 patients with 27 episodes of pyogenic abscesses was carried out at the University Medical Centre, Amsterdam. Out of 27 episodes, 15 (55%) were associated with biliary or pancreatic disease; in seven of these 15 episodes more than one microorganism was cultured. Enterobacteriaceae were isolated in 13 (85%) of 15 episodes. Anaerobic bacteria were recovered only when operations in the pancreatico-biliary area had been performed previously. Seven episodes (26%) were related to extrahepatic disease; anaerobic bacteria (Bacteroides and Fusobacterium spp.) were isolated in five of these seven episodes. Streptococcus milleri seemed especially prominent, since this bacterium was cultured in six of seven episodes. Enterobacteriaceae were not involved in these seven episodes. Other factors predisposing to liver abscesses (15%) were diabetes mellitus n = 2), paraproteinaemia (n = I), and metastatic carcinoid (n = I). Blood cultures were positive in 65% of 23 episodes, but 40% of the positive cultures contained a smaller number of bacterial species than could be cultured from the abscess itself. Bacteria isolated from liver abscesses are related to the underlying predisposing condition. For diagnosis of the underlying condition and antibiotic therapy, puncture and bacteriologic examination of the abscess is essential.

Adult↗
PubMed1991

Meningococcal chest infections in a general hospital.

In the course of one calendar year (1989-1990), 46 specimens of respiratory secretions (from 44 patients) cultured in the microbiology department of a large district general hospital in The Netherlands were found to yield Neisseria meningitidis. Twenty-eight of the 46 samples yielded pure cultures of meningococci and 18 yielded other recognised respiratory pathogens as well. Only one patient had pneumonia, whereas 19 had acute respiratory infections and 18 acute purulent exacerbations of chronic bronchitis. The remaining patients, who had a variety of symptoms, all had purulent sputum. Only 8 of the 44 patients were under 40 years of age; 21 were aged more than 60 years. Serological grouping and subtyping showed a predominance of group B strains (in 24 of 44 patients) and 13 strains were non-groupable. The importance of recognising or overlooking meningococci in cultures of respiratory secretions is discussed.

Acute Disease↗
PubMed1991

Adhesion of Escherichia coli on to a series of poly(methacrylates) differing in charge and hydrophobicity.

The adhesion of three Escherichia coli strains on to six poly(methacrylates) differing in hydrophobicity and surface charge was measured as a function of time under laminar flow conditions. Polymers used were poly(methyl methacrylate) (PMMA), poly(hydroxyethyl methacrylate) (PHEMA) and copolymers of MMA or HEMA with either 15% methacrylic acid (MAA) or 15% trimethylaminoethyl methacrylate-HCl salt (TMAEMA-Cl). Bacterial and polymer surfaces were characterized by means of water contact angles and zeta potentials. Both the sessile drop contact angles and the zeta potentials of the bacterial surfaces were significantly different. No significant differences in the sessile drop contact angles of the polymer surfaces were observed. Using the Wilhelmy plate technique large contact angle hysteresis was observed for the different polymer surfaces. Surfaces of copolymers with MAA had more negative zeta potentials than those of the corresponding homopolymers. Surfaces of copolymers with TMAEMA-Cl had positive zeta potentials. The highest numbers of adherent bacteria were found on materials with positive zeta potentials, irrespective of the bacterial strain used. Bacterial adhesion on to copolymers with MAA was less than on to the corresponding homopolymers. Bacterial equilibrium adhesion values correlate with the zeta potentials of the polymer surfaces (r greater than 0.85). On substrates with less negative zeta potentials high numbers of adhered bacteria were observed. Additionally, the equilibrium bacterial adhesion values could be related with receding contact angles of polymer surfaces with negative zeta potentials (r greater than 0.86). High equilibrium adhesion values were obtained for polymers with high contact angles. No correlation between the zeta potentials and contact angles of the bacteria with the adhesion values was found.

Bacterial Adhesion↗
PubMed1991

Bacterial contamination of growth hormone solution and injection equipment during use by growth hormone deficient children.

The frequency of bacterial contamination of growth hormone solution and injection equipment use by 20 growth hormone deficient children was studied. In a cross-over study the children were randomized to begin using, for their growth hormone injections, either the recently developed growth hormone injection pen or the conventional syringe method. A comparison was then made of these two methods of injection over a 6-week period and the vials, pen-cartridges, syringes and needles were cultured. When the pen was used 5.3% of the 114 vials, 15.5% of the 110 cartridges and 11.2% of the 98 needles were found to be contaminated; when the syringe was used 3.5% of the 113 vials, 7.1% of the 98 syringes and 9.1% of the 99 needles were contaminated. To ensure microbiological safety during the preparation and injection of the growth hormone solution, regular instruction and reassessment of the injection technique for patients on long-term treatment are advocated. This applies even when disposable items are used. As no statistically significant difference was noted between the number of contaminated items used with either the pen or the syringe method, we conclude that the growth hormone pen is suitable for growth hormone administration.

Adolescent↗
PubMed1991

Differential binding of Haemophilus influenzae to human tissues by fimbriae.

The hypothesis was investigated that tissue tropism of Haemophilus influenzae during colonisation and infection is associated with the ability of fimbriate bacteria to bind to the organs and cell types involved. H. influenzae type b with fimbriae (strain 770235f+) bound to several cell types, including ciliated columnar epithelial cells, pneumocytes, ependymal cells, glial cells, connective tissue fibroblasts, synovial cells, antigen-presenting cells, lymphocytes, erythrocytes and endothelial cells. Binding of H. influenzae to kidney, liver and conjunctiva cells was poor. Fimbriae-specific monoclonal antibody (MAb 6HE8) inhibited this binding. Some binding to endothelial cells and macrophages was also observed with non-fimbriate strains. This binding was not inhibited by MAb 6HE8. We conclude that in-vitro binding of fimbriate H. influenzae is mainly to those tissues and cells where H. influenzae is found during colonisation and infection. The data suggest that a shift to the non-fimbriate form is required for bacteria in the bloodstream to escape clearance mechanisms mediated by blood cells.

Adenoids↗
PubMed1991

Immunochemical characterization of variable epitopes of outer membrane protein P2 of nontypeable Haemophilus influenzae.

Monoclonal antibodies (MAbs) were elicited to the nontypeable Haemophilus influenzae variants d1 to d4, which differ in the outer membrane protein P2 to analyze the immunological properties of the variable parts of this protein. Five MAbs reacted in a whole-cell enzyme-linked immunosorbent assay (ELISA) only with the homologous strain and in some cases with its variants, but not with 69 unrelated nonencapsulated H. influenzae isolates; nine MAbs also reacted with some other H. influenzae isolates, and four MAbs showed broad cross-reactivity. All of the MAbs reacted with purified protein P2 in ELISAs and immunoblotting. The five MAbs which reacted with the homologous strain d3 and not with the variants d1, d2, and d4 promoted complement-dependent bactericidal activity against strain d3. These and four other MAbs reacted with the intact bacteria of strain d3 in immunogold electron microscopy, indicating that they were directed against surface-exposed epitopes of outer membrane protein P2. A mutant of strain d3 was isolated as a survivor from bacterial killing by complement and MAb 30DA5. This mutant had an altered P2 protein on sodium dodecyl sulfate-polyacrylamide gels and had lost its reactivity with all of the five H. influenzae d3-specific MAbs but not with the other MAbs. From these results, we conclude that the variable parts of outer membrane protein P2 of nonencapsulated H. influenzae from the sputum of patients with chronic obstructive pulmonary disease are immunogenic and mostly surface exposed. Only strain-specific MAbs promoted complement-dependent killing of the bacteria, which was abolished in a spontaneous mutant with an altered P2 protein.

Animals↗
PubMed1991

Blocking of fimbria-mediated adherence of Haemophilus influenzae by sialyl gangliosides.

The structure of the receptor for the fimbriae of Haemophilus influenzae on human oropharyngeal epithelial cells and erythrocytes was determined in inhibition experiments with various sugars, glycolipids, and glycoproteins. Of 30 monosaccharides and disaccharides at a concentration of 0.1 M and of 3 polysaccharides at a concentration of 1 mg/ml, none inhibited fimbria-specific adherence and hemagglutination. Inhibition was obtained with gangliosides GM1, GM2, GM3, and GD1a in nanomolar concentrations, whereas the asialo derivative of GM1, sialyl-lactose, and sialoglycoproteins were poor inhibitors. These findings indicate that sialyl-lactosylceramide (GM3) is the minimal structure for the fimbria-dependent binding of H. influenzae to its receptor on oropharyngeal epithelial cells and erythrocytes. As is the case with GM2, substitution of GM3 with N-acetylgalactosamine makes the molecule a 10-fold-better receptor analog.

Bacterial Adhesion↗
PubMed1991

Adherence of coagulase-negative staphylococci onto polyethylene catheters in vitro and in vivo: a study on the influence of various plasma proteins.

Bacterial adherence on PE catheters inserted into the carotid artery of rabbits was assessed at 5, 30, and 240 min after injection with bacteria of five coagulase-negative staphylococci (CN Staph). These studies revealed that CN Staph adhere onto PE catheters 5 min after injection with bacteria. At 240 min after injection with bacteria almost all catheters were sterile, indicating that initially adherent bacteria on PE catheters disappear with time. EM studies revealed high numbers of platelets and leukocytes and many fibrin deposits on the surface of the PE catheter. In addition, the adherence of the five test strains on PE catheters was determined in vitro. In these in vitro studies the bacteria and catheters were pretreated with either fibrinogen, fibronectin, albumin or citrated whole plasma or the liquid adherence medium was supplemented with these proteins or the adherence assay was done in citrated whole plasma. The presence of proteins in the adherence medium or pretreatment of the catheter or bacteria with either fibronectin, albumin or whole citrated plasma markedly inhibited bacterial adherence. In contrast, pretreatment of bacteria or both bacteria and catheters with fibrinogen enhanced bacterial adherence suggesting the presence of ligands for fibrinogen on the cell surface of CN Staph.

Animals↗
PubMed1990

Frequency of the delta F508 mutation and XV2c,KM19 haplotypes in cystic fibrosis families from The Netherlands: haplotypes without delta F508 still in disequilibrium.

We have determined the frequency of the major cystic fibrosis (CF) three base pair deletion (delta F508) mutation in 152 CF chromosomes from patients originating from the northern part of The Netherlands. In these patients, the deletion represents approximately 76% of CF mutations. Meconium ileus is strongly associated with homozygosity for the delta F508 mutation. The XV2c,KM19 haplotypes on the CF chromosomes without the delta F508 mutation are in disequilibrium with the population frequency, although showing an increased frequency of the 1 2 haplotype. The surplus of this haplotype is almost entirely made up by the pancreatic insufficient patients.

Cystic Fibrosis↗
PubMed1990

Combined inheritance of epithelial and erythrocyte receptors for Haemophilus influenzae.

Haemophilus influenzae type b expressing fimbriae showed no adherence to buccal epithelial cells and no agglutination of erythrocytes from three AnWj-negative siblings in one family. Hemagglutination of erythrocytes from 13 AnWj-positive members of the same family and from 24 controls was normal, and H. influenzae adhered well to buccal epithelial cells from them. These data indicate that the expression of epithelial and erythrocyte receptors for H. influenzae is inherited concomitantly. Combined with previous data (L. van Alphen, J. Poole, L. Geelen, and H. Zanen, Infect. Immun. 55:2355-2358, 1987), the results show that the receptor molecules on the surfaces of the epithelial cell and the erythrocyte are different but that the binding sites for the fimbriae of H. influenzae are similar.

Antigens↗
PubMed1989

Physicochemical surface properties of nonencapsulated and encapsulated coagulase-negative staphylococci.

Cell surfaces of three nonencapsulated and three encapsulated coagulase-negative staphylococci were characterized by their surface free energies, zeta potentials, and elemental and molecular compositions. Surface free energies were calculated from contact angle measurements with various liquids. All six strains showed a high surface free energy (103 to 126 mJ.m-2), estimated from the concept of polar and dispersion components. However, the hydrogen-donating surface free energy parameter was zero for all nonencapsulated strains. The zeta potential profile measured as a function of pH in phosphate-buffered saline for the nonencapsulated strains was completely different from that of the encapsulated strains. X-ray photoelectron spectroscopy was used to determine the elements (O, C, N, P, and K) in the outer 2 to 5 nm of the freeze-dried cell surface and showed that the hydrophilic character of the staphylococci was related to oxygen (O/C ratio, approximately 0.52)- and phosphorus (P/C ratio, approximately 0.03)-containing groups. Both the elemental and molecular characterizations (done by infrared spectroscopy) pointed to the presence of polysaccharides and polypeptides on the cell surface of the nonencapsulated and encapsulated strains.

Bacterial Adhesion↗