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Biomedical subjects

J Dankert

Publications and source records attributed to J Dankert.

At least 127 records · Page 7Linked to original sources
PubMed1997

Helicobacter pylori reinfection is virtually absent after successful eradication.

This study examined whether reinfection or recrudescence accounts for the reappearance of Helicobacter pylori infection after apparent successful eradication. In a prospective study, 173 patients cured from H. pylori infection underwent follow-up endoscopies, with biopsies for culture and histopathology, every 3 months during the first year after treatment. Subsequently, elective half-yearly endoscopies were performed in 124 patients; the remaining 49 underwent follow-up endoscopy only in 1995. At reappearing infection, DNA profiles of pretreatment and recurrent strains were compared. After 3.5 years (range, 1.0-9.2), H. pylori infection recurred in 9 patients (5.2%). Reappearing infections were classified as endoscopically transmitted reinfection (n = 2), unclassified because of loss of pretreatment isolate (n = 1), or recrudescence (identical DNA patterns before and after treatment; n = 6). The reappearance rate of infection, discarding endoscopic transmission, was 1.2% (7/601 H. pylori-negative patient-years). There was virtually no reinfection with H. pylori after eradication in this adult Western population. These data do not rule out acquisition of H. pylori.

Adult↗
PubMed1997

No increase in endotoxin release during antibiotic killing of meningococci.

Endotoxin is liberated following antibiotic killing of Gram-negative rods, and antibiotics may differ in this respect. Although the amount of filterable endotoxin has also been reported to increase following antibiotic killing of meningococci, it is unknown how this influences the host response. We investigated the influence of three antibiotics on levels of free endotoxin in culture medium and cytokine production in whole blood ex vivo during killing of four strains of meningococci. Bacterial killing was significantly more efficient with penicillin or ceftriaxone than with chloramphenicol, and free endotoxin levels were lower after exposure to antibiotics as compared with no treatment (ANOVA, P < 0.001). Endotoxin levels were lowest after exposure to chloramphenicol. In three of the four strains exposure to antibiotics resulted in considerably lower cytokine levels (ANOVA, P < 0.001), and TNF-alpha levels were significantly lower after exposure to penicillin or ceftriaxone than after chloramphenicol treatment. Only in the strain that induced the lowest levels of TNF-alpha were cytokine levels comparable for untreated and treated samples. We conclude that fear of excessive endotoxin release or cytokine production caused by effective antibiotics is not justified in the treatment of meningococcal infections.

Anti-Bacterial Agents↗
PubMed1997

Meropenem susceptibility of Neisseria meningitidis and Streptococcus pneumoniae from meningitis patients in The Netherlands.

In-vitro susceptibility of 299 Neisseria meningitidis and 157 Streptococcus pneumoniae strains from meningitis patients in The Netherlands in 1993 and 1994 to meropenem was determined using the Etest. Susceptibility to penicillin, ceftriaxone, and chloramphenicol was also determined. Rifampicin susceptibility was additionally tested for N. meningitidis. Of the meningococci, 4.3% were of intermediate resistance to penicillin and 0.3% were resistant to rifampicin. One pneumococcal isolate (0.6%) was of intermediate resistance to penicillin. All strains were susceptible to meropenem. We conclude that meropenem is in vitro highly active against N. meningitidis and S. pneumoniae.

Anti-Bacterial Agents↗
PubMed1997

Genetic and phenotypic analysis of Borrelia valaisiana sp. nov. (Borrelia genomic groups VS116 and M19).

To clarify the taxonomic status of two recently described Borrelia genomic groups, groups VS116 and M19, three group VS116 strains and eight group M19 strains isolated from Ixodes ricinus ticks in Switzerland, The Netherlands, and the United Kingdom were characterized. PCR-restriction fragment length polymorphism (RFLP) analysis of the 5S-23S intergenic spacer amplicon, rRNA gene restriction analysis, 16S rRNA gene sequence analysis, randomly amplified polymorphic DNA (RAPD) fingerprinting, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and immunoblotting with monoclonal antibodies were used for genetic and phenotypic analysis. The PCR-RFLP and RAPD patterns of three group VS116 strains and eight group M19 strains were identical but differed from those of Borrelia burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii, and Borrelia japonica. DNAs from all group VS116 and M19 strains yielded three fragments (6.9, 3.2, and 1.4 kb) and four fragments (2.1, 1.2, 0.8, and 0.6 kb) after digestion with EcoRV and HindIII, respectively, hybridizing with an Escherichia coli 16S + 23S cDNA probe. The SDS-PAGE protein profiles of group VS116 and M19 strains were heterogeneous. Phylogenetic analysis of the partial 16S rRNA gene sequences showed that group VS116 and M19 spirochetes were members of a Borrelia species distinct from previously characterized members of the genus Borrelia. Based on our present study and data from previous DNA-DNA hybridizations, a new Borrelia species, Borrelia valaisiana sp.nov., in the B. burgdorferi complex, is proposed. Strain VS116 is the type strain of this new species.

Bacterial Proteins↗
PubMed1997

Complement-mediated serum sensitivity among spirochetes that cause Lyme disease.

Borrelia burgdorferi-related isolates were tested for their sensitivity to normal human serum (NHS) and their ability to activate complement. By dark-field microscopy, electron microscopy, and subsurface plating, it was shown that exposure of a Borrelia garinii isolate to 10% or more NHS resulted in immobilization, blebbing, and killing of the spirochetes. These effects were mediated by complement, since they were not seen after heat treatment of NHS, in the presence of EDTA, or in an agammaglobulinemic serum. All seven B. garinii type 5 or 6 and all four VS116/M19 strains were serum sensitive, whereas all eight Borrelia afzelii, five of eight B. garinii type 4, and three of seven B. burgdorferi sensu stricto isolates were serum resistant. The other isolates were partially serum sensitive. Four serum-sensitive B. garinii isolates had been isolated from human cerebrospinal fluid. Most likely, activation of both the alternative pathway and the classical pathway of complement was involved, since bactericidal activity was diminished in properdin-deficient sera as well as in a C1q-depleted serum and in a C4-deficient serum. Bactericidal activity could be restored when a serum lacking C1q or C4 was mixed with a properdin-deficient serum. Isolates with various genetic backgrounds were equally able to activate C3 as measured by enzyme-linked immunosorbent assay. In the presence of Mg-EGTA, C3 was activated by all isolates after exposure to > or = 10% NHS. This study shows that B. burgdorferi-related spirochetes can be either serum sensitive or serum resistant in vitro and that this characteristic is associated with their genetic background.

Borrelia burgdorferi Group↗
PubMed1997

Molecular variation in the major outer membrane protein P5 gene of nonencapsulated Haemophilus influenzae during chronic infections.

During the course of persistent infections by nonencapsulated Haemophilus influenzae in patients with chronic bronchitis, the major outer membrane protein (MOMP) P5 varies in molecular weight. The nature of this variability was determined by DNA sequence analysis of the P5 gene from five different H. influenzae strains and their seven MOMP P5 variants which were isolated from patients with chronic infections of the lower respiratory tract. Analysis of the P5 sequence data from the different strains revealed four well-defined, heterogeneous regions. These regions of variable sequence appeared to correspond to the regions of the gene encoding the putative surface-exposed loops of MOMP P5. The MOMP P5 variants with alterations in MOMP P5 were shown to result from DNA point mutations and codon deletions. In addition, in three variants derived sequentially from one H. influenzae strain, a frameshift mutation resulted in the formation of a stop codon in the region encoding the signal sequence of the MOMP P5 gene. Strikingly, all nucleotide substitutions in the MOMP P5 loop regions of variants were nonsynonymous, suggesting that variants with alterated amino acid compositions of the surface-exposed parts of MOMP P5 obtained a selective advantage during persistence of the infection by nonencapsulated H. influenzae in chronic bronchitis patients.

Amino Acid Sequence↗
PubMed1997

Equally high prevalences of infection with cagA-positive Helicobacter pylori in Chinese patients with peptic ulcer disease and those with chronic gastritis-associated dyspepsia.

Approximately 60% of Helicobacter pylori isolates in the Western world possess the cytotoxin-associated gene A (cagA). cagA-positive H. pylori is found to be associated with peptic ulcer disease (PUD) and gastric adenocarcinoma. To investigate the cagA status of H. pylori isolates from Chinese patients with PUD and chronic gastritis (CG), H. pylori populations from 83 patients, 48 with PUD and 35 with CG, were assessed by two different cagA-specific PCRs, Southern blotting, and colony hybridization. The combined results from PCR, Southern blotting, and colony hybridization indicate a prevalence of cagA-positive H. pylori isolates of 98% (47 of 48) among Chinese PUD patients and 100% (35 of 35) among Chinese CG patients. Amplification with primer sets 1 and 2 yielded 52 and 95% of the 82 cagA-positive Chinese H. pylori, respectively. In contrast, the sensitivity of cagA-specific PCR for cagA-positive H. pylori isolates from Dutch patients with primer set 1 was 92% (112 of 122) and that with primer set 2 was 91% (50 of 55). The prevalence of cagA-positive H. pylori populations in Chinese patients with PUD and CG is almost universally high. Therefore, cagA cannot be used as a marker for the presence of PUD in Chinese patients. Our data further suggest that allelic variation in cagA may exist and that distinct H. pylori genotypes may circulate in China and Western Europe.

Adult↗
PubMed1997

Frequency of pathogenic and enteroadherent Escherichia coli in patients with inflammatory bowel disease and controls.

AIMS: To determine whether inflammatory bowel disease (IBD) is associated with pathogenic or enteroadherent Escherichia coli. METHODS: A least two stool specimens and one rectal biopsy were taken from 30 patients with IBD and from 20 controls. A large number of E coli-like colonies cultured from each stool sample and biopsy was tested, using DNA probes, for the presence of genes encoding shiga-like toxins, invasiveness, attachment-effacement and the ability to adhere to HEp-2 cells. Similarity among isolates from stool samples and rectal biopsies was determined by random amplified polymorphic DNA (RAPD) analysis. RESULTS: Enterohaemorrhagic and enteroinvasive E coli were not found in samples from either patients or controls. No significant difference in the detection rate of enteroadherent E coli between patients and controls was found. Rectal biopsies from 11 of 28 patients with IBD and 4 of 18 controls contained E coli, which hybridised with probes for detection of genes encoding diffuse adherence to HEp-2 cells, or encoding P-pili (p = 0.2). Enteroadherent E coli isolated from two or three stool specimens from the same patient or control appeared to be identical by RAPD analysis, and are considered to be residents in the colon. Probe positive isolates obtained from stool specimens and corresponding rectal biopsies were always identical on RAPD analysis. CONCLUSIONS: E coli strains possessing adherence factors reside in the large intestine and adhere to the rectal mucosa, irrespective of the presence of colitis.

Adult↗
PubMed1997

Persisting Haemophilus influenzae strains induce lower levels of interleukin-6 and interleukin-8 in H292 lung epithelial cells than nonpersisting strains.

Nonencapsulated Haemophilus influenzae strains isolated from patients with chronic bronchitis can be divided into those that persist in the lower respiratory tract and those that do not. We tested the hypothesis that persisting and nonpersisting strains differ in the extent to which they activate epithelial cells to produce two potent inflammatory mediators, interleukin (IL)-6 and IL-8. A suspension of 10(7) and 10(8) colony forming units (cfu) x mL(-1) of H. influenzae, persisting and nonpersisting, induced a dose- and time-dependent production of IL-6 and IL-8 by the human pulmonary mucoepidermoid carcinoma-derived cell line H292, but levels of IL-6 were lower after exposure to persisting H. influenzae (p<0.05). IL-8 production showed a similar trend (p<0.02; analysis of variance). H. influenzae bacteria that adhered to H292 cells were equally distributed over persisting and nonpersisting isolates and induced IL-6 and IL-8 levels similar to their nonadhering counterparts. The difference between persisting and nonpersisting H. influenzae was not due to cytotoxic, antimetabolic or antiproliferative effects on H292 cells. Furthermore, pre-exposure of cells to persisting and nonpersisting isolates did not block subsequent IL-1beta-induced IL-6 production. We conclude that persisting clinical isolates induce less interleukin-6 and interleukin-8 in H292 cells than nonpersisting isolates, probably because they excrete lower amounts of a stimulus of H292 cells. The stimulus is heat stable, hydrophilic and nonproteinous and probably not lipopolysaccharide alone. These findings support the suggestion that some strains of Haemophilus influenzae that persist in the airways of patients, may do so because they induce only a weak inflammatory response.

Analysis of Variance↗
PubMed1997

Iron-binding proteins in sputum of chronic bronchitis patients with Haemophilus influenzae infections.

Airway inflammation during infection is associated with increased transudation of serum proteins and increased production of protein by the airway epithelium. We therefore, assessed whether Haemophilus influenzae infections in patients with chronic bronchitis are associated with increased levels of transferrin and lactoferrin in the sputum compared to uninfected patients. Sputum sol phase and serum samples from 14 infected and 13 uninfected patients with chronic bronchitis and from 12 bronchial asthma patients were included in the study. The median Q-values (the concentration in sputum sol phase/the concentration in serum) x 10(3) of transferrin appeared increased in chronic bronchitis patients with an H. influenzae infection (26.0, n=13) compared to uninfected controls (9.5, n=11) and bronchial asthma patients (4.5, n=6). The ratio of the Q(transferrin)/Q(albumin) was >1 in infected chronic bronchitis patients, indicating local production of transferrin. Growth of H. influenzae was stimulated more in sputum from infected and uninfected patients with chronic bronchitis than in sputum from patients with bronchial asthma. The concentrations of lactoferrin were not significantly different in infected (n=14) and uninfected (n=13) chronic bronchitis patients and bronchial asthma patients (n=12) (median 137.4, 84.6, 87.1 mg x L(-1), respectively). We conclude that in patients with chronic bronchitis with Haemophilus influenzae infections, the levels of transferrin are increased and the levels of lactoferrin are not associated with infections.

Adult↗
PubMed1996

Piperacillin to prevent cholangitis after endoscopic retrograde cholangiopancreatography. A randomized, controlled trial.

BACKGROUND: Cholangitis does not often occur after endoscopic retrograde cholangiopancreatography (ERCP), but it can be a serious complication of this procedure. Antibiotic prophylaxis is therefore frequently used in patients having ERCP, but existing data are insufficient to allow evaluation of the effectiveness of this practice. OBJECTIVE: To determine the efficacy of single-dose antibiotic prophylaxis with piperacillin for ERCP-induced cholangitis. DESIGN: Randomized, double-blind, placebo-controlled clinical trial. SETTING: Tertiary referral center for ERCP. PATIENTS: Patients who had ERCP for suspected biliary tract stones or distal common bile duct stricture were eligible. Major exclusion criteria were previous ERCP within 7 days, biliary endoprosthesis in situ, and use of antimicrobial agents or presence of fever within 7 days before the procedure. INTERVENTION: Piperacillin, 4 g, or placebo was given intravenously approximately 30 minutes before ERCP. MEASUREMENTS: Duration of follow-up was 1 week. Acute cholangitis was diagnosed if a patient had a body temperature greater than 38 degrees C, a clinically apparent need for antibiotic treatment, and no symptoms indicating infection outside of the biliary tree. RESULTS: 551 consecutive patients were enrolled. During ERCP, stones were found in 147 patients, malignant distal strictures were found in 203 patients, other pathologic findings were seen in 88 patients, and normal biliary tracts were seen in 113 patients. Seventeen of the 281 patients who received placebo (6.0%) and 12 of the 270 patients who received piperacillin (4.4%) developed acute cholangitis (relative risk, 0.73 [95% CI, 0.36 to 1.51]). The absolute risk reduction was 1.6% (CI, -5.3% to 2.1%). All cases of cholangitis (with the exception of one case seen in a patient in the piperacillin group) were mild or moderate in severity. CONCLUSION: Single-dose prophylaxis with piperacillin is not associated with a clinically significant reduction in the incidence of acute cholangitis after ERCP in patients suspected of having biliary tract stones or distal common bile duct stricture.

Adult↗
PubMed1996

[3 emerging protozoal infections in The Netherlands: Cyclospora, Dientamoeba, and Microspora infections].

Increased international travelling, an increased number of patients with immunosuppression caused by HIV infection, and renewed interest in known but little studied microorganisms, resulted in a more frequent finding of certain medically important parasites. Three emerging protozoal infection, Cyclospora cayetanensis, Dientamoeba fragilis and Microspora (Enterocytozoon bieneusi and Encephalitizoon) are causative agents of diarrhoea. Encephalitozoon infections are also associated with hepatitis, hepatoconjunctivitis and nephritis. C. cayetanensis infection was diagnosed in 28 patients in the years 1992-1995 in the Academic Medical Centre in Amsterdam, half of these patients returning from a visit to Indonesia. D. fragilis has a prevalence in the Netherlands of 8% among patients with diarrhoea lasting longer than one week referred for parasitological investigation. The prevalence of E. bieneusi in HIV positive patients with diarrhoea was 8-10% in the Academic Medical Centre in the last five years. Infection with Encephalitozoon appears to be endemic in the Netherlands.

Animals↗
PubMed1996

Effect of specimen collection techniques, transport media, and incubation of cultures on the detection rate of Helicobacter pylori.

Culture and histologic examination are considered "gold standard" methods for the detection of Helicobacter pylori, but discrepancies may occur with either method. Failure to detect Helicobacter pylori may be due to sampling error, inappropriate transport or culture media, or insufficient duration of the incubation period. Rates of detection of Helicobacter pylori by culture and histopathologic examination of gastric mucosal biopsy specimens were determined in 102 consecutive dyspeptic patients. In a separate group of 60 patients, rates of detection of Helicobacter pylori by culture of antral brushings and the length of incubation required in selective and nonselective culture media were studied. In the first group of 102 patients, the combination of culture and histologic examination detected 54 Helicobacter pylori-positive patients, whereas the separate techniques each detected 51 Helicobacter pylori-positive patients. In the second group of 60 patients evaluated by culture of antral brushings, the rate of detection of Helicobacter pylori was 25 of 60 and was similar for culture (25/60) and histologic examination (25/60). In the second group the length of incubation required to detect Helicobacter pylori was different for selective and nonselective media. In nonselective media, incubation of up to ten days was required to detect all Helicobacter pylori infections, whereas in selective media seven days was sufficient. Rates of detection of Helicobacter pylori by culture, histopathologic examination and culture from brushings were similar, whereas the combination of culture and histopathologic examination achieved a superior rate of detection. The incubation period required for the detection of Helicobacter pylori by culture was a minimum of seven days and was dependent on the culture medium used.

Adult↗
PubMed1996

Prevention of infection in children with acute leukaemia. No major difference between total and selective bowel decontamination.

To evaluate the effect of total bowel decontamination (TD) and selective bowel decontamination (SD) in a non-protective environment clinical and laboratory data of children treated for acute leukaemia between 1983 and 1991 were analysed retrospectively. From 1983 until 1989 34 patients [18 acute non-lymphoblastic leukaemia (ANLL) patients, 16 acute lymphoblastic leukaemia (ALL) patients] received TD and 31 patients (8 ANLL patients, 23 ALL patients) received SD from 1987 until 1991. TD consisted of colistin sulphate, neomycin, cephaloridine and amphotericin B orally as well as Orabase and sterilized food, while the patients were nursed in a single room. SD consisted of oral colistin sulphate, neomycin and amphotericin B. Those patients with ANLL were nursed in a single room; patients with ALL were nursed in a single room during remission induction therapy only. All patients except those with ANLL receiving TD received Pneumocystis carinii pneumonia prophylaxis with cotrimoxazole. Because the two groups were heterogeneous for diagnosis and chemotherapy the occurrence of fever (central body temperature at least 38.5 degrees C) and major infections (septicaemia of infections of the deep tissues or organs) were registered during periods of neutropenia (neutrophilic granulocytes < or = 500/mm3 for at least 8 days). Patients on TD had 55 periods of neutropenia, patients on SD 80. Patients on TD had 89.1 periods of fever/100 periods of neutropenia whereas patients on SD had 56.3. Also patients on TD had 27.3 major infections/100 periods of neutropenia whereas patients on SD had 11.3. Major infections predominantly consisted of septicaemia caused by gram-positive bacteria. We conclude that, in this study, TD in a non-protective environment does not offer better protection against major infections that SD in patients with ALL or ANLL.

Adolescent↗
PubMed1996

Treatment of Helicobacter pylori infection with low or high dose omeprazole combined with amoxycillin and the effect of early retreatment.

BACKGROUND: Cure rates of H. pylori infection, using dual therapy with omeprazole and amoxycillin, vary considerably and the efficacy of retreatment with this regimen in the case of initial failure is controversial. Therefore, we conducted a large prospective double-blind randomized trial, studying the efficacy of low vs. high dose omeprazole in dual therapy and of early retreatment with the same regimens. METHODS: One hundred and sixty-eight consecutive H. pylori-positive patients, suffering from either peptic ulcer disease or functional dyspepsia, were enrolled. Group I (n = 84) received omeprazole 20 mg b.d. plus amoxycillin 750 mg t.d.s., for 2 weeks. Group II (n = 84) received omeprazole 40 mg t.d.s. plus amoxicillin 750 mg t.d.s., for 2 weeks. RESULTS: The H. pylori eradication rate was 60.2% in group I and 64.3% in group II (P = 0.59). Cure of H. pylori infection was significantly better in patients with peptic ulcer disease, compared to non-ulcer dyspeptics (P = 0.016). Retreatment, given in 54 patients, was successful in 21.4% patients in group I and in 28% patients in group II (P = 0.58). CONCLUSIONS: High dose of omeprazole has no advantage compared to low dose in terms of eradication efficacy. Early retreatment with the same regimen offers limited improvement in cure rate. Presence of peptic ulcer disease influences cure rates significantly.

Adolescent↗
PubMed1996

Heterozygous and homozygous factor H deficiency states in a Dutch family.

Factor H, a 150-kD protein, is an important down-regulating protein of the alternative pathway of the complement system. Presently, only 15 persons, representing seven families, have been described with homozygous factor H deficiency. Deficiency of this protein, inherited as an autosomal recessive trait and resulting in uncontrolled breakdown of C3, results in depletion of components of the alternative pathway (factor B, properdin) and of the terminal pathway (C5), and is associated with the onset of bacterial infections, glomerulonephritis and systemic lupus erythematosus (SLE). The proband of the family in this study suffered from subacute cutaneous lupus erythematosus and had had meningococcal meningitis due to serogroup X. She had a complete factor H deficiency at the protein level as determined by Western blotting. Among 21 relatives of the proband studied, encompassing three generations, 10 had low factor H levels, including the two children of the proband, indicating a heterozygous factor H deficiency state. In serum samples of the proband and 11 relatives prospectively studied, a strong correlation of factor H levels with C3, C3 haemolytic activity, factor B and properdin levels (P < 0.0001) was found. Alternative pathway protein levels were significantly lower (Mann-Whitney test; Z values 3.6-2.7) in sera from the four heterozygous relatives studied than in sera from the seven non-deficient relatives. In addition, a defect of the 37/42-kD H-related protein was found in the proband and two of 21 relatives, compared with four of 40 controls. A defect of the 24/29-kD H-related protein was present in one of 21 relatives studied and in none of the 40 controls.

Complement Factor H↗
PubMed1996

Heterogeneous Helicobacter pylori isolates from members of a family with a history of peptic ulcer disease.

BACKGROUND & AIMS: Duodenal ulcer formation in persons infected with Helicobacter pylori correlates with the expression of the cytotoxin-associated gene A (cagA) and the vacuolating cytotoxin (VacA). The aim of this study was to assess the occurrence of cagA and VacA variants among H. pylori isolates. METHODS: H. pylori was isolated from 8 members of one family with a history of peptic ulcer disease (PUD). Each strain was characterized by random amplified polymorphic DNA (RAPD) fingerprinting. cagA was detected by polymerase chain reaction (PCR), Southern blotting, and colony hybridization. Viable H. pylori was added to mammalian cells to assess their cytotoxin activity. RESULTS: The RAPD patterns of the 8 patients' strains were similar. Analysis of 10 single colonies from the primary culture plates showed that all but 1 subject harbored multiple H. pylori subtypes. The proportion of cagA-positive colonies on the primary culture plates ranged from 0% to 90% between the isolates from all patients. In addition, the different H. pylori subtypes showed no cytotoxin activity in mammalian cells. CONCLUSIONS: Genotypic comparison of H. pylori isolated from different patients requires analysis of multiple colonies selected from the primary culture plate. In addition, infection by cagA-positive H. pylori in the family members with PUD (subjects 2-8) is consistent with the observed association between cagA positivity and PUD.

Adult↗