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B Wretlind

Publications and source records attributed to B Wretlind.

At least 73 records · Page 4Linked to original sources
PubMed1990

Genetic mapping of the structural gene for phospholipase C of Pseudomonas aeruginosa PAO.

An insertion mutation constructed by gene replacement methods was used to map the gene corresponding to the hemolytic phospholipase C (plcS gene) in Pseudomonas aeruginosa PAO1 by R68.45-mediated conjugation. plcS mapped approximately at 67 min on the 75-min chromosomal map (B. W. Holloway, K. O'Hoy, and H. Matsumoto, p. 213-221, in S. J. O'Brien, ed., Genetic Maps 1987, vol. 4, 1987), between the markers pur-67 and pru-375 and considerably distal to the regulatory genes plcA and plcB, which are located at approximately 12 min.

Chromosome Mapping↗
PubMed1989

Comparison of Western blot and enzyme-linked immunosorbent assay for diagnosis of Lyme borreliosis.

The usefulness of Western blot in the serological diagnosis of Lyme borreliosis was evaluated compared with an ELISA using a whole cell sonicate antigen. Fifty-three of 68 (78%) patients with neuroborreliosis had positive IgM and/or IgG immunoblots and 40 of 68 (59%) had positive IgM and/or IgG ELISA titers in serum. Eight of 44 (18%) controls with meningitis/encephalitis of non-borrelia etiology had positive IgM and/or IgG immunoblots and 4 of 44 (9%) had positive IgM and/or IgG ELISA titers in serum. Western blot was more sensitive than ELISA, the difference being most pronounced in sera from patients with neurological disease for four weeks or less. Both patients and controls lived in an area endemic for Lyme borreliosis and some ELISA negative but Western blot positive controls were thought to have been previously exposed to Borrelia burgdorferi. However, the specificity for current disease was not improved by Western blot. In conclusion, Western blot does not seem to be the method of choice for screening purposes in a routine laboratory but can be used as a complement to ELISA for serodiagnosis in patients with disease of short duration.

Adolescent↗
PubMed1989

Cloning of xcp genes located at the 55 min region of the chromosome and involved in protein secretion in Pseudomonas aeruginosa.

Pleiotropic mutations (xcp) affecting secretion of proteins in Pseudomonas aeruginosa have been previously characterized and mapped at 0 min, 55 min and 65 min. Genomic libraries of this organism have been constructed and the genes xcp-5 and xcp-54, located at the 55 min region, were cloned using the adjacent met allele as a marker, and complementation of xcp strains. From our linkage and cloning analysis, the most probable gene order in this region appears to be pyrD... xcp-5/xcp-54/met-9011/oru-314/trpF/leu-10. Restriction mapping and transposon (Tn1725) insertion mutagenesis demonstrated that: (i) the overall size of DNA necessary for xcp expression was 9kb, (ii) the two loci are not adjacent on the chromosome, and (iii) the two loci are expressed independently. The xcp-5 gene has been subcloned on a 4kb EcoRI fragment.

Bacterial Proteins↗
PubMed1989

Nasopharyngeal culture with quantitative analysis of pathogenes in chronic otitis media with effusion. Effects on pathogen yield of different swabs and transport methods.

The influence of different swabs and transport media on nasopharyngeal culture pathogen recovery has been studied in patients with chronic otitis media with effusion. Transport times of less than two hours have been used. Protecting the cotton wire swab with a polyethylene shealth to prevent contamination by nasal flora did not have any significant influence either on the recovery of potential pathogens or on the contaminating nasal flora. Facilitating a quantitative analysis of the nasopharyngeal culture by transporting the specimen in empty tubes gave a pathogen recovery rate similar to that with transport in Stuart medium, whereas an attempt at transporting in sodium chloride or prereduced PY broth led to significantly lower yields of Branhamella catarrhalis (p less than 0.01) and in PY broth on Haemophilus influenzae as well (p less than 0.01).

Child, Preschool↗
PubMed1989

Test-retest reliability of the nasopharyngeal culture in children.

Aspects of test-retest reliability of the nasopharyngeal culture were evaluated in children with otitis media and in ear, nose and throat (ENT)-healthy children, in all 174 cases. The nasopharyngeal colonization of Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis and beta-haemolytic streptococci was determined for a group of children with well-defined otitis media effusion (OME). The valitity of the results was then tested in a new group of children with OME. Despite seasonal differences and different bacteriologists analysing the specimens, high conformity was found between the two groups regarding distribution and recovery rates of the potential pathogens studied. The test-retest reliability of the culture was also analysed by duplicate specimens in children with acute otitis media (AOM), OME and in ENT-healthy children. The reproducibility of the findings of pathogens, whether quantitative aspects were considered or not, was found to be between 70 and 80% for children with AOM and OME.

Bacteria↗
PubMed1989

Mutations in the hemolytic-phospholipase C operon result in decreased virulence of Pseudomonas aeruginosa PAO1 grown under phosphate-limiting conditions.

The phospholipase C (PLC) operon of Pseudomonas aeruginosa consists of plcS, which encodes a heat-labile secreted hemolysin, and two in-phase, overlapping genes, plcR1 and plcR2, which may encode Pi-regulatory genes. A 2.8-kilobase-pair deletion mutation in this operon was constructed, and a tetracycline resistance (Tcr) cartridge replaced the deleted sequences. A deletion mutant of strain PAO1 was obtained through recombination between the flanking regions of the mutated cloned PLC operon and the homologous chromosomal regions. The deletion of the chromosomal PLC operon and its replacement by the Tcr cartridge was confirmed by Southern hybridization. The deletion strain, PLC SR, is nonhemolytic. However, it retains PLC activity when measured on a synthetic substrate. A second mutant strain, PLC R, contains a deletion in the plcR genes. This mutant is more hemolytic and produces more enzymatic activity than PAO1. The virulence of both of these mutants was compared with that of PAO1 in the mouse burn model of infection. When mice were infected with cultures grown in a high-Pi medium, there was a 10-fold increase in the 50% lethal dose of the mutants compared with PAO1. In contrast, when the inoculum originated from low-Pi cultures, there was a 200- to 10,000-fold increase in the 50% lethal dose of the mutants over PAO1.

Animals↗
PubMed1989

Protein secretion in Pseudomonas aeruginosa: molecular cloning and characterization of the xcp-1 gene.

Pleiotropic mutations (xcp) affecting the secretion of proteins in Pseudomonas aeruginosa have been previously characterized and mapped at three different loci on the chromosome. The xcp-1 gene, which is located at the 0-min region, was isolated from a genomic bank containing DNA from P. aeruginosa PAO1. The recombinant cosmid pLX25 complemented the xcp::Tn5-751 insertion mutation previously described. The xcp-1 gene was located on pLX25 by mapping the insertion point of transposon Tn5-751 and by deletion and subcloning analysis. The xcp-1 gene was expressed when transcription was initiated from a tac promoter, and a 26,000-dalton protein was identified in Escherichia coli minicells. The Xcp-1 protein was associated with the membrane fraction of E. coli. A 30-kilodalton outer membrane protein was also affected by the xcp::Tn5-751 mutation in P. aeruginosa. The possible correlation between Xcp-1 and this protein is discussed.

Bacterial Proteins↗
PubMed1988

Aerobactin-mediated uptake of iron by strains of Escherichia coli causing acute pyelonephritis and bacteraemia.

A total of 285 strains of Escherichia coli isolated from children and women with acute non-obstructive pyelonephritis and from patients with bacteraemia as well as 120 faecal strains of E. coli from healthy children and adults were examined for aerobactin-mediated uptake of iron. The incidence of aerobactin-positive strains was significantly more in isolates from children with acute pyelonephritis (81%) than in faecal isolates from healthy children (50%, P less than 0.01). It was also higher in isolates of E. coli from women with acute pyelonephritis (72%) compared with faecal isolates from healthy adults (42%, P less than 0.001). Of the E. coli strains causing bacteraemia, 55% were aerobactin-positive. A significant correlation was found between the presence of aerobactin and expression of P-fimbriae in strains of E. coli isolated from children with acute pyelonephritis (P less than 0.01) and in isolates from bacteraemic patients (P less than 0.001). These results indicate that the presence of an aerobactin-mediated system of iron uptake may be an important virulence factor in strains of E. coli that cause ascending pyelonephritis.

Acute Disease↗
PubMed1988

Imipenem/cilastatin, an alternative treatment of pseudomonas infection in cystic fibrosis.

Imipenem, a new N-formimidoyl thienamycin was given together with cilastatin to 20 patients with cystic fibrosis and pulmonary infection due to Pseudomonas aeruginosa. The antibiotic was given in short-term infusions for 9-14 days (mean 11.5) in a dose of 45-60 mg/kg body weight/day. Good clinical results were obtained in all patients with significant improvement of clinical score, pulse rate, vital capacity and FEV1.0 (P less than 0.001). Blood PO2 increased and WBC decreased significantly. A slight increase in the minimum inhibitory concentration was noted during treatment but all strains examined were fully susceptible at follow-up one month later. The peak serum concentration was significantly increased in patients receiving the high dose of imipenem, but the sputum concentration was low in all patients and there was no difference in clinical or bacteriological outcome. The plasma and urinary clearance increased with body weight and was inversely correlated to clinical score. Imipenem/cilastatin appears a good alternative for the treatment of pulmonary infections caused by P. aeruginosa in cystic fibrosis.

Adolescent↗
PubMed1988

Treatment of Lyme borreliosis with emphasis on neurological disease.

We have studied 113 patients with neurologic Lyme borreliosis and meningitis who were treated with intravenous high-dose antibiotics (penicillin G, 12 g, mostly for 14 days in 47 patients; penicillin G, 9 g, mostly for 10 days in 58 patients; doxycycline, 200 mg, in 5 patients; and cefuroxime, 4.5-9 g, in 3 patients). Seventy percent of the patients had peripheral nerve symptoms and 13% had central nervous symptoms. Almost half of the patients were treated more than 4 weeks after the onset of symptoms and 15% of the patients had persisting or progressive symptoms between 4 and 11 months. There seemed to be clinical benefit as well as a decrease of spinal fluid pleocytosis and spinal proteins. No significant symptoms of Herxheimer reaction were demonstrated.

Anti-Bacterial Agents↗
PubMed1988

Enzyme-linked immunosorbent assay to evaluate the immunogenicity of a polyvalent Klebsiella capsular polysaccharide vaccine in humans.

A highly sensitive enzyme-linked immunosorbent assay was developed for Klebsiella capsular polysaccharide (CPS) and used to evaluate the immunoglobulin G (IgG) antibody response to a 24-valent CPS vaccine in seven adult volunteers. The median rise in titer to all vaccine antigens in samples from the volunteers was significant (twofold or greater). Significant IgG responses to 11 immunologically related serotypes not included in the vaccine were also noted. The mean cross-reacting IgG titer of 127.2 was only slightly lower than the mean titer of 175.7 to the serotypes in the vaccine (P less than 0.05). The mean 29.9-fold increase in titer to the serotypes in the vaccine was significantly higher than the mean 13.5-fold increase in titer to the additional antigens (P less than 0.001). The difference was partly because of the significantly lower (P less than 0.01) natural antibody titers in the preimmune sera to the serotypes in the vaccine, compared with those to serotypes not included in the vaccine. The selection of vaccine serotypes was based on the frequency of serotype isolation from cases of Klebsiella bacteremia. The above findings, which show low levels of natural antibody to these serotypes, support the hypothesis that anti-CPS antibody is protective against bacteremic disease.

Antibody Formation↗
PubMed1988

Evaluation of serologic assays for diagnosis of whooping cough.

An enzyme-linked immunosorbent assay (ELISA) for the immunoglobulin G (IgG), IgM, and IgA response to Bordetella pertussis filamentous hemagglutinin (FHA) and pertussis toxin (PT) and a neutralization test (NT) in a microplate tissue culture assay for neutralizing antibodies to PT were evaluated in paired sera from 90 patients with culture-confirmed pertussis. Eighty patients were children (age, less than 15 years), and 6 of 80 children had been immunized with three doses of diphtheria-tetanus-pertussis vaccine as infants. A significant titer rise (greater than or equal to twofold), determined by ELISA, of IgG, IgM, and IgA to FHA was recorded in 75 (83%), 28 (31%), and 47 (52%) of the patients, respectively. A significant titer rise to PT in IgG was found in 83 (92%), IgM in 29 (32%), and IgA in 44 (49%) of the patients. A significant titer rise to FHA or PT in IgG was found in 88 (98%) of the patients, in combination with a significant rise in the titer of IgA to FHA. These data were obtained in a single serum dilution of 1:500. Titrations performed later showed that the titer rise to FHA in IgG was a mean of 6.5-fold, which was significantly lower than the mean 67.0-fold rise in IgG to PT (P less than 0.001). The mean titer of IgG to FHA in convalescent-phase serum was 270, which was also significantly lower than the mean PT titer of 2,943 (P less than 0.001). A significant rise (greater than or equal to fourfold) in PT titer by NT was found in 58 of 83 (70%) of the patients. The NT was significantly less sensitive than the ELISA for the determination of the IgG titer to PT ( P< 0.001). Results showed that a 100% (90 of 90) sensitivity in terms of titer rises was achieved in the serologic diagnosis of pertussis by ELISA in a single-point determination of the IgG and IgA responses to FHA and of the IgG response to PT.

Adolescent↗
PubMed1987

Assessment of elastase as a Pseudomonas aeruginosa virulence factor in experimental lung infection in mink.

Anaesthetized mink were inoculated intratracheally with an elastase-producing Pseudomonas aeruginosa strain (PAO1) and two mutants derived from PAO1 with defective elastase formation (strains PAO1-E64 and PAO1-las-16). Survival times were prolonged in mink infected with the mutants, and microscopic examination of lungs showed that the elastase-positive wild type strain produced more pronounced tissue damage and haemorrhages than did the elastase-defective mutant strains. The strains PAO1 and PAO1-las-16 were also compared to three strains isolated from natural infection in mink which differed in elastase production. The mink strains with high or moderate elastase production produced more severe lung damage and were associated with a higher mortality than the other strains tested. The results indicate that P. aeruginosa may enhance the virulence of the bacterium in lung infections.

Animals↗
PubMed1987

Role of exotoxin A and elastase in the pathogenicity of Pseudomonas aeruginosa strain PAO experimental mouse burn infection.

We examined the virulence of Pseudomonas aeruginosa strain PAO and xcp (extracellular proteins deficient) and xch (extracellular proteins hyperproducing) mutants derived from strain PAO in an experimental mouse burn infection model. The results showed that xcp mutants, which produced little or no extracellular elastase and exotoxin A, were as virulent as their corresponding xcp+ strains. The xch mutants produced more elastase and exotoxin A than the wild type strain, however, they had significantly lower virulence, probably due to reduced ability of these strains to take up iron. Treatment of mice with ferric ammonium citrate had no effect on the wild type strain but enhanced mortality in mice challenged with xch mutants. Neither elastase nor exotoxin A seem to play any role in burn infections with P. aeruginosa strain PAO. However, ability for iron uptake is an important virulence factor.

ADP Ribose Transferases↗
PubMed1987

Plasmid analysis as an epidemiological tool in neurosurgical infections with coagulase-negative staphylococci.

Coagulase-negative staphylococci isolated from blood or spinal fluid during a period of 1 year in a department of neurosurgery, were analysed by biotyping, antibiotic resistance pattern and plasmid profiles. Altogether 41 isolates from 19 patients were studied. About 90% of the isolates were Staphylococcus epidermidis. The antibiotic resistance pattern seemed to be closely related to antibiotic usage in the unit. Most common was resistance to penicillin (63%), trimethoprim-sulphamethoxazole (49%) and cloxacillin (39%) while resistance to gentamicin was seen in only one strain. In several cases species and antibiograms were identical in isolates from different patients. Plasmid pattern analysis could then be used for identification of different strains. In one instance, plasmid pattern and restriction enzyme analysis confirmed that two patients probably were infected by the same strain.

Anti-Bacterial Agents↗
PubMed1987

The use of biochemical markers, serotype and fimbriation in the detection of Escherichia coli clones.

Biochemical reactions, O and K serotypes and presence of P-fimbriae were analysed in 116 Escherichia coli strains isolated in blood cultures from patients with bacteraemia and in 99 faecal strains isolated from healthy individuals. By using biochemical typing, the strains could be grouped into six main clusters with similarity index less than 0.8 (Gower, 1971) and altogether 16 subclusters with similarity index 0.82-0.89. The most discriminating tests between the clusters were fermentation of D-tagatose, saccharose, salicin and sorbose. No single biochemical property could differentiate bacteraemic isolates from faecal strains, although strains isolated from blood were significantly more often found in certain subclusters, whereas other subclusters contained mainly control strains. Bacteraemic strains possessed P-fimbriae more often, especially strains isolated from patients with E. coli in the urine concomitantly with bacteraemia. Equally, no single reaction could separate P-fimbriated from non-P-fimbriated strains. D-Tagatose was fermented more often by the P-fimbriated strains; on the other hand, melibiose and lactose fermentation tests were less often positive. Certain O serotypes (O1, O4, O6, O7, O18 and O25) were more common among bacteraemic isolates than controls. K serotypes such as K1, K5 and K52 were also more frequent among blood isolates. We conclude that a combination of biochemical tests, fimbriation and serotyping might be used to identify potentially pathogenic clusters of E. coli.

Adolescent↗