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N Hoiby

Publications and source records attributed to N Hoiby.

At least 19 recordsLinked to original sources
PubMed2000

Pseudomonas aeruginosa cross-infection among patients with cystic fibrosis during a winter camp.

Twenty-seven patients with cystic fibrosis from our Danish Cystic Fibrosis Center went to a winter camp for 1 week in November of 1990. This study is based on 22 of these patients. Prior to attending camp, 17 out of 22 patients harbored Pseudomonas aeruginosa in their sputum, but 5 patients did not. After returning from camp, all 22 patients harbored P. aeruginosa in the sputum, including the 5 patients whose sputum was free of P. aeruginosa before they went. Epidemiological typing used pulsed-field gel electrophoresis of the P. aeruginosa isolates was performed. The typing results showed that the 5 cystic fibrosis patients who were free of P. aeruginosa in their sputum prior to the winter camp had acquired P. aeruginosa isolates identical to the P. aeruginosa strains isolated from the other 17 cystic fibrosis patients. This constitutes a cross-colonization rate of 100%, the highest rate ever detected among patients with cystic fibrosis. We conclude that separate holiday camps based on the infection status of the patients with cystic fibrosis are necessary to avoid cross-infection of patients not infected with P. aeruginosa.

Adolescent↗
PubMed2000

Sequencing of the rpoB gene in Legionella pneumophila and characterization of mutations associated with rifampin resistance in the Legionellaceae.

Rifampin in combination with erythromycin is a recommended treatment for severe cases of legionellosis. Mutations in the rpoB gene are known to cause rifampin resistance in Escherichia coli and Mycobacterium tuberculosis, and the purpose of the present study was to investigate a possible similar resistance mechanism within the members of the family Legionellaceae. Since the RNA polymerase genes of this genus have never been characterized, the DNA sequence of the Legionella pneumophila rpoB gene was determined by the Vectorette technique for genome walking. A 4,647-bp DNA sequence that contained the open reading frame (ORF) of the rpoB gene (4,104 bp) and an ORF of 384 bp representing part of the rpoC gene was obtained. A 316-bp DNA fragment in the center of the L. pneumophila rpoB gene, corresponding to a previously described site for mutations leading to rifampin resistance in M. tuberculosis, was sequenced from 18 rifampin-resistant Legionella isolates representing four species (L. bozemanii, L. longbeachae, L. micdadei, and L. pneumophila), and the sequences were compared to the sequences of the fragments from the parent (rifampin-sensitive) strains. Six single-base mutations which led to amino acid substitutions at five different positions were identified. A single strain did not contain any mutations in the 316-bp fragment. This study represents the characterization of a hitherto undescribed resistance mechanism within the family Legionellaceae.

Amino Acid Sequence↗
PubMed2000

Excretion of beta-lactam antibiotics in sweat--a neglected mechanism for development of antibiotic resistance?

The concentrations of beta-lactam antibiotics after standard doses were measured in blood and apocrine (axilla) and eccrine (forearm) sweat from six adult healthy persons. All persons had ceftazidime (axilla, 28.4 microg/ml; forearm, 11 microg/ml) and ceftriaxone (axilla, 8.9 microg/ml; forearm, 2.5 microg/ml) in sweat, and one person had cefuroxime in sweat (axilla, 7.8 microg/ml) (all data are mean peaks). Three persons had benzylpenicillin (axilla, 2.6 to 0.1 microg/ml) and one had phenoxymethylpenicillin (axilla, 0.4 microg/ml) in sweat. Excretion of beta-lactam antibiotics in the sweat may explain why staphylococci so rapidly become resistant to these drugs.

Administration, Oral↗
PubMed2000

Molecular mechanisms of fluoroquinolone resistance in Pseudomonas aeruginosa isolates from cystic fibrosis patients.

Twenty P. aeruginosa isolates were collected from six cystic fibrosis (CF) patients, aged 27 to 33, in 1994 (9 isolates) and 1997 (11 isolates) at the CF Center, Copenhagen, Denmark, and were typed by pulse-field gel electrophoresis (PFGE) or ribotyping. Five of the patients had isolates with the same PFGE or ribotyping patterns in 1997 as in 1994, and ciprofloxacin had a two- to fourfold higher MIC for the isolates collected in 1997 than those from 1994. Genomic DNA was amplified for gyrA, parC, mexR, and nfxB by PCR and sequenced. Eleven isolates had mutations in gyrA, seven isolates had mutations at codon 83 (Thr to Ile), and four isolates had mutations at codon 87 (Asp to Asn or Tyr). Sixteen isolates had mutations in nfxB at codon 82 (Arg to Leu). Increased amounts of OprN were found in six isolates and OprJ in eight isolates as determined by immunoblotting. No isolates had mutations in parC or mexR. Six isolates had mutations in efflux pumps without gyrA mutations. The average number of mutations was higher in isolates from 1997 than in those from 1994. The results also suggested that efflux resistance mechanisms are more common in isolates from CF patients than in strains from urine and wounds from non-CF patients, in which mutations in gyrA and parC dominate (S. Jalal and B. Wretlind, Microb. Drug Resist. 4:257-261, 1998).

Adult↗
PubMed1998

Subspecific differentiation of Burkholderia cepacia isolates in cystic fibrosis.

Thirty clinical isolates of Burkholderia cepacia from cystic fibrosis (CF) patients in the UK and Denmark were characterised, together with other clinical isolates and laboratory strains of B. cepacia, B. gladioli and B. vietnamiensis. Outer-membrane protein (OMP) profiles were determined, and the organisms were typed genotypically by pulsed-field gel electrophoresis after DNA restriction analyses with Xbal and DraI. This latter method revealed four clusters among the clinical isolates studied; one of these contained isolates of the UK and intercontinental CF epidemic lineage ET12, a cluster which appeared to contain three subtypes. Each of the four clusters appeared less closely related to laboratory strains of B. cepacia than were laboratory strains of B. vietnamiensis, but more closely related to both these species than to B. gladioli. Two types of OMP profile were distinguished among the clinical isolates and strains, and were designated A and B. In type A isolates the major proteins had mol.wts of 39, 27 and 18 kDa. Type B strains additionally contained a group of proteins in the size range 80-90 kDa, although detection of these depended upon the conditions for sample denaturation. In most cases, the OMP type correlated with the genotype, suggesting that examination of OMPs might be of value in the initial characterisation of isolates.

Bacterial Outer Membrane Proteins↗
PubMed1998

Effects of ginseng treatment on neutrophil chemiluminescence and immunoglobulin G subclasses in a rat model of chronic Pseudomonas aeruginosa pneumonia.

Chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients is almost impossible to eradicate with antibiotic treatment. In the present study, the effects of treatment with the Chinese herbal medicine ginseng on blood polymorphonuclear leukocyte (PMN) chemiluminescence and serum specific antibody responses were studied in a rat model of chronic P. aeruginosa pneumonia mimicking CF. An aqueous extract of ginseng was administered by subcutaneous injection at a dosage of 25 mg/kg of body weight/day for 2 weeks. Saline was used as a control. Two weeks after the start of ginseng treatment, significantly increased PMN chemiluminescence (P </= 0. 001) and a decreased level in serum of immunoglobulin G (IgG) against P. aeruginosa (P < 0.05) were found. Furthermore, a higher IgG2a level (P < 0.04) but lower IgG1 level (P < 0.04) were found in the ginseng-treated infected group than in the control group. In the ginseng-treated group the macroscopic lung pathology was milder (P = 0.0003) and the percent PMNs in the cells collected by bronchoalveolar lavage was lower (P = 0.0006) than in the control group. However, the alveolar macrophage (AM) chemiluminescence values were not significantly different in the two groups infected with P. aeruginosa. The differences between the ginseng-treated noninfected rats and the control group (without P. aeruginosa lung infection) for the PMN chemiluminescence and AM chemiluminescence were not significant. These results suggest that ginseng treatment leads to an activation of PMNs and modulation of the IgG response to P. aeruginosa, enhancing the bacterial clearance and thereby reducing the formation of immune complexes, resulting in a milder lung pathology. The changes in IgG1 and IgG2a subclasses indicate a possible shift from a Th-2-like to a Th-1-like response. These findings indicate that the therapeutic effects of ginseng may be related to activation of a Th-1 type of cellular immunity and down-regulation of humoral immunity.

Animals↗
PubMed1977

Immune complexes in cystic fibrosis.

Eleven patients with cystic fibrosis (CF) chronically infected with mucoid P. aeruginosa and ten patients without P. aeruginosa infection were examined for occurrence of circulating immune complexes, for immune complex deposits in the dermo-epidermal junction of the skin and for precipitins against P. aeruginosa, S. aureus, H. influenzae and D. pneumoniae antigens. The serum concentrations of haptoglobin, orosomucoid, immunoglobulins, C1q, C3, C4 and total haemolytic complement, antinuclear and rheumatoid factor activities as well as white blood cell counts and erythrocyte sedimentation rates were determined also. The results indicated that 6 patients from the chronically P. aeruginosa infected group, exhibiting a spectrum of serum precipitins against P. aeruginosa antigens, also had immune complexes in the serum, while only one patient (suffering from selective IgA deficiency) in the group without P. aeruginosa infection was positive for soluble immune complexes. Granular deposits of IgM was found in the skin of 10 of the chronically P. aeruginosa infected patients and in 7 of the patients without P. aeruginosa infection. A few pactients in both groups had dermo-epidermal deposits of C1q, C3 or fibrinogen as well. Eight of the patients in the chronically infected group and five in the group without P. aeruginosa infection had organ non-specific antinuclear factors. The haptoglobin levels appeared to be elevated in the chronically infected patients (p less than 0.05). None of the other parameters showed any significant difference between the two groups.

Adolescent↗
PubMed1977

Pseudomonas aeruginosa infection in cystic fibrosis. Diagnostic and prognostic significance of Pseudomonas aeruginosa precipitins determined by means of crossed immunoelectrophoresis.

A total of 133 patients with cystic fibrosis have been followed for up to 5 years with monthly examinations including bacteriological examinations of sputum. Sera from the patients were examined by means of crossed immunoelectrophoresis for the occurence and number of precipitating antibody specificites against Pseudomonas aeruginosa. Poor prognosis in cystic fibrosis was associated with chronic colonization (9 months - more than 5 years) of the respiratory tract with mucoid Pseudomonas aeruginosa, and with an onset of the chronic colonization before puberty. Among the patients with chronic Pseudomonas aeruginosa colonization, poor prognosis was associated with high numbers of precipitins against antigens from these bacteria (up to 61). The number of Pseudomonas aeruginosa precipitins increased on an average with five per year in chronically colonized patients. Rapidly increasing number of precipitins was associated with poor prognosis. Patients with any degree of impairment of the ventilatory function and any changes on the chest radiographs could contract chronic Pseudomonas aeruginosa colonization. Poor ventilatory function and severe changes on the chest radiographs was associated with high numbers of Pseudomonas aeruginosa precipitins and with poor prognosis. Although many O groups of Pseudomonas aeruginosa were found in the chronically colonized group of patients, 53% of the patients harboured strains belonging to O group 3 or 3/9, and the highest numbers of precipitins were found in serum from these patients.

Antibodies, Bacterial↗
PubMed1976

Haemophilus from the lower respiratory tract of patients with cystic fibrosis.

Fifty-six non-haemolytic Haemophilus strains were isolated during current bacteriological examinations from material from the lower respiratory tract of 39 patients with cystic fibrosis during a 6-month period. Except for six strains which belonged to Haemophilus parainfluenzae, all strains were identified as Haemophilus influenzae. Biotype I of H. influenzae was the predominating taxon (38%) and was especially related to patients with recurrent or prolonged colonization. Only two strains were capsulated. An unexpectedly high percentage of the strains produced lysine decarboxylase. The significance of this property in the pathogenesis of the respiratory tract colonization is discussed.

Adolescent↗
PubMed1976

The serology of Pseudomonas aeruginosa analysed by means of quantitative immunoelectrophoretic methods. V. Thermostability, resistance to degradation by plasmin activity and storage conditions of a polyvalent P. aeruginosa reference standard-antigen.

The stability of a polyvalent Pseudomonas aeruginosa antigen (St-Ag) was analysed under different experimental conditions by quantitative immunoelectrophoretic methods. St-Ag did not undergo proteolytic degradation by plasmin which is present in the corresponding polyvalent rabbit antiserum (St-Ab) against St-Ag. Storage at -30 degrees C for up to 4 years caused no qualitative changes in St-Ag and, after 1 year, only minor quantitative changes could be revealed. Repeated thawing and freezing caused no changes in St-Ag whereas storage at 4 degrees C, or at room temperature, caused gradual degradation of most of the antigens of St-Ag, beginning after 1 week. Heating up to 40 degrees C for 2 min did not change St-Ag, but heating for longer periods of time or at higher temperatures gradually destroyed most of the antigens of St-Ag. The most thermostable antigen in St-Ag was number 37 which is related to the group specific O antigens.

Antigens, Bacterial↗
PubMed1976

Serological types of Diplococcus pneumoniae isolated from the respiratory tract of children with cystic fibrosis and children with other diseases.

The distribution of serological types of D. pneumoniae was investigated in 40 strains isolated from 26 children with cystic fibrosis and 57 strains isolated from 39 children with other diseases. All strains were isolated from sputum or tracheal secretion. The strains from cystic fibrosis patients belonged to 14 different serological types, the most prevalent were 19F, 19A and 3. The strains from the other group of children belonged to 20 different serological types, the most prevalent were 23F, 19F and 11A. The differences between the two groups of patients as to the prevalences of types were small, and it is concluded that no special serological types of D. pneumoniae are associated with cystic fibrosis.

Adolescent↗
PubMed1976

The serology of Pseudomonas aeruginosa analysed by means of quantitative immunoelectrophoretic methods.

The conformity of the immunoprecipitate pattern obtained with a polyvalent Pseudomonas aeruginosa antigen (St-Ag) and different pools of a polyvalent, purified (IgG and IgA) rabbit antiserum (St-Ab) against St-Ag has been studied. Ten rabbits were immunized and bled every fifth week. Eight pools of St-Ab were produced during nearly four years. All the St-Ab pools were mutually compared by means of quantitative immuno-electrophoretic methods. All St-Ab pools were found to present St-Ag/St-Ab immunoprecipitate patterns which, qualitatively and quantitatively, were similar. None of the obtained immunoprecipitates between St-Ag and the pooled antisera disappeared during the procedures of purification of IgG and IgA. Quantitative and qualitative comparison of the polyvalent St-Ab pools ("titre") was made by counting the total number of immunoprecipitates obtained by St-Ag, followed by their identification, and by calculating the mean area of 12 selected and representative immunoprecipitate. The abilities of the rabbits to produce antibodies were found to vary individually. None of the rabbits produced precipitating antibodies against all the 64 known P. aeruginosa antigens in St-Ag. On the average, each of the rabbits lacked precipitating antibodies against 5 of the antigens. By pooling antisera from 3 rabbits out of 8 only 14 per cent of the possible combinations would contain detectable precipitins against all the known antigens of St-Ag.

Animals↗
PubMed1976

Sequential studies of lymphocyte responsiveness and antibody formation in acute bacterial meningitis.

Lymphocyte transformation responses in vitro were studied in eight patients with acute bacterial meningitis (in five due to Neisseria meningitidis). Sequential studies were done from 24--48 hr after the first symptoms of infection to complete recovery. In all cases lymphocyte transformation was depressed during the acute phases of illness. The responses to microbial antigens were more affected than the responses to mitogens. The course of the lymphocyte responses to the causative micro-organism showed no difference from the responses to other microbial species. A moderate shift towards increased sensitivity of the lymphocytes to lower doses of the causative micro-organism was observed during the course of illness in three cases. In N. meningitidis infection, a rapid rise was seen in the serum titres of complement-fixing antibodies and in the number of precipitating antibodies, whereas the rise in immunoglobulin concentrations was more prolonged. Characteristic patterns of elevation and return towards normal were found in the serum concentrations of the acute-phase reactants alpha1-antitrypsin, haptoglobin, and orosomucoid. It is concluded that the lymphocyte transformation responses in vitro during severe bacterial infection are largely governed by non-specific factors, and that studies of lymphocyte responses to micro-organisms should always include other microbial species as controls.

Antibody Formation↗
PubMed1975

The serology of Pseudomonas aeruginosa analysed by means of quantitative immunoelectrophoretic methods. I. Comparison of thirteen O groups of Ps. aeruginosa, with a polyvalent Ps. aeruginosa antigen-antibody reference system.

Serologic cross-reactions between 26 strains of Pseudomonas aeruginosa representing 13 O groups were studied by various quantitative immunoelectrophoretic techniques. As reference system was used a polyvalent Ps. aeruginosa antigen and a corresponding rabbit antiserum. Fifty-one (93 per cent) of the 55 Ps. aeruginosa antigens in the reference system were present in all the strains and corresponding antibodies in the reference system could be completely absorbed by all the strains. Complete cross-reactivity was also found between antigens of the reference system and 3 of the 4 antigens present only in some of the strains. The last of the 4 antigens not present in all the strains could only absorb part of the corresponding antibodies in the reference system. Absorption experiments with whole heat-killed bacteria indicate that this antigen is related to the O group antigens of Ps. aeruginosa. None of the antigens of the reference system were related to the mucoid substance produced by some strains of this bacterium.

Animals↗