Biomedical subjects

B Wretlind

Publications and source records attributed to B Wretlind.

At least 91 records · Page 5Linked to original sources

PubMed1987

Characterization of a Pseudomonas aeruginosa transposon insertion mutant with defective release of exoenzymes.

A Pseudomonas aeruginosa transposon insertion mutant with defective release of several exoenzymes has been characterized. The Tn5-751 insertion mutation was located in the previously described xcp-1 locus at 0 min on the chromosomal map and caused several exoenzymes to remain in cell-bound form. At least one of the exoenzymes, elastase, was accumulated in the periplasmic space. The periplasmic elastase had the same Mr as the extracellular enzyme produced by the wild-type strain. The virulence of the mutant was comparable to that of wild-type strains in experimental burn infection in mice. The presence of an easily selectable antibiotic resistance marker in the xcp-1 locus offers the possibility of cloning the gene(s) involved in exoprotein secretion.

ADP Ribose Transferases↗

PubMed1987

Prospective study of serum antibodies to Pseudomonas aeruginosa exoproteins in cystic fibrosis.

Serum immunoglobulin G to four purified antigens from Pseudomonas aeruginosa, phospholipase C, alkaline protease, exotoxin A, and elastase, were determined in 62 patients with cystic fibrosis by enzyme-linked immunosorbent assay. The patients were followed for 12 to 24 months in a prospective study. Increased titers, i.e., titers more than 2 standard deviations above those of normal controls, were exclusively found in patients chronically colonized with P. aeruginosa and not in patients harboring only Staphylococcus aureus. The frequencies of elevated titers of antibody to the different antigens varied from 100% (phospholipase C) to 58% (alkaline protease and exotoxin A) to 15% (elastase) in the chronically colonized patients. Mean serum titer levels, expressed as multiples of the age-correlated upper normal limit (=1), were significantly higher to phospholipase C in patients with dual colonization with P. aeruginosa and S. aureus than in those colonized only with P. aeruginosa (P less than 0.001). Conversely, the other three antigens showed significantly higher serum antibody titer levels in patients harboring only P. aeruginosa (P less than 0.001). In five patients who became colonized with P. aeruginosa during the study period, serum antibodies to phospholipase C and exotoxin A increased first. Exceptions to the general pattern of antibody responses were found in three patients chronically colonized with Escherichia coli. They showed a delayed enhancement of anti-phospholipase C titers after the chronic P. aeruginosa colonization. Serum titers were not influenced by exacerbations of pulmonary infection or by antimicrobial therapy. The determination of titers of serum antibody to phospholipase C seems to be a valuable indicator of a chronic colonization with P. aeruginosa. The results further suggest that bacterial metabolism and interactions may influence the antibody response.

ADP Ribose Transferases↗

PubMed1986

Antibody responses to Escherichia coli J5 lipopolysaccharide and to Salmonella porin in patients with bacteremia.

This study was undertaken in order to evaluate whether patients with bacteremia respond with antibodies directed towards two outer membrane components of Gram-negative bacteria. The antibody responses to the core of the lipopolysaccharide molecule (LPS) of the rough E. coli J5 mutant and to a purified outer membrane protein (porin) from Salmonella were studied in bacteremic patients. Two or three serum samples were consecutively collected from 77 patients having 82 episodes of bacteremia altogether, of these 50 were caused by bacteria of the genus Enterobacteriaceae. As controls, sera from 82 age and sex matched patients and 100 healthy blood donors were analysed. The antibody titers were assessed by enzyme-linked immunosorbent assays (ELISA). None of the patients with bacteremia responded with an increase in antibody level to the E. coli J5 rough LPS. This finding indicates that the core portion of the E. coli J5 LPS contains no antigenic epitopes immunologically cross-reactive with Gram-negative bacteria causing bacteremia. By contrast, 13 patients showed significant titer increases to the porin preparation derived from Salmonella. Twelve of these patients had bacteremia caused by Gram-negative organisms belonging to Enterobacteriaceae. One patient had bacteremia with Bacteroides fragilis but also suffered from a severe peritonitis with growth of both E. coli and Klebsiella. It is suggested that the measurement of antibody response to porin may be of value for differential serological diagnosis in patients with bacteremia, to distinguish between Enterobacteriaceae and other organisms.

Adult↗

PubMed1986

A simplified model for adjustment of gentamicin dosage in newborn infants.

In a retrospective study of 72 neonates during treatment with gentamicin, poor correlation was found between dosage based on body weight and gentamicin serum concentrations. Calculation of adequate gentamicin dosage regimen during steady-state based on individual pharmacokinetic parameters according to Gibaldi & Perrier was then studied in 35 newborn infants during therapy. Predictions were based on gentamicin serum concentrations taken prior to and 1, 3, and 5 hours after the first (n = 8) or second (n = 12) dose (group A), or only prior to and one hour after dose (group B, n = 15). Half-life (t1/2), apparent volume of distribution (Vd), body clearance (Clbody) and elimination rate constant (beta) were not significantly different when calculated after the first or second dose or during steady-state. The correlation between predicted and observed gentamicin concentration was high in both groups (p less than 0.005) and the slopes congruent with unity. After dose or interval correction, 73% of the observed predose concentrations (mean 2.0 micrograms/ml) were within 1 microgram/ml of predicted values. One hour after dose the predicted (mean 5.7 micrograms/ml) and observed (mean 6.2 micrograms/ml) values were not significantly different. Higher precision was noted when the predictions were based on 4 samples (group A) compared to 2 (group B). Since the calculations may be performed by a simple desk calculator rapid advice may be given to the clinical staff on adequate gentamicin dosage even in small severely ill preterm infants.

Bacterial Infections↗

PubMed1986

A comparison of different methods for determining elastase activity of Pseudomonas aeruginosa strains from mink.

We have characterized 20 Pseudomonas aeruginosa strains isolated from pneumonic mink lungs with regard to elastase production and serotype. P. aeruginosa PAO1, a well-characterized elastase-producing strain, and two elastase-deficient mutants of PAO1 were used for comparative purposes. Elastase activity was assayed on elastin agar and by using 14C-elastin coated microtiter plates. Elastase antigen was measured using a double antibody sandwich ELISA (enzyme-linked immunosorbent assay). Total proteolytic activity was determined on skim milk agar plates. The results from ELISA showed that all strains produced antigenically similar elastase, although the amounts produced varied considerably between strains. There was a good correlation regarding elastase assays between ELISA and 14C-elastin, elastin agar and total proteolytic activity on skim milk agar. No correlation was found between serotype and elastase activity. The results showed that the 14C-elastin assay is a simple and sensitive method of determining elastolytic activity of P. aeruginosa strains.

Animals↗

PubMed1985

Use of the antimicrobial removal device prior to blood culture in patients on antibiotic therapy.

The efficacy of the antimicrobial removal device in facilitating isolation of bacteria from blood containing antibiotics was evaluated in a multicenter study. Blood specimens from 143 patients who had culture-proven septicemia and had been on antibiotic treatment for at least 24 hours were recultured with and without the aid of the device. Septicemia persisted in 33 of the patients and use of the device improved the isolation rates: 63% of the gram-positive bacteria and 32% of the gram-negative bacteria were isolated only with the aid of the device. Use of the device was an advantage in 10 of 13 cases where the antibiotic concentration in the bottles exceeded the MIC for the infecting microorganism but in only 5 of 19 cases where the concentration was lower than the MIC. It is concluded that the antimicrobial removal device may be useful in patients already on antibiotic treatment, but that its use is limited by the cost and the amount of work involved.

Adsorption↗

PubMed1985

Occurrence of P-fimbriated Escherichia coli in patients with bacteremia.

The case history of 88 patients with blood cultures positive for Escherichia coli and evidence of systemic disease was reviewed, and the Escherichia coli blood isolates tested for P-fimbriation. Fifty-five strains (63%) were P-fimbriated. Patients with a positive urine culture had a higher incidence of P-fimbriated Escherichia coli strains (53/75, 71%) than patients with a negative urine culture (2/13, 15%). Patients with no predisposing factors, such as instrumentation of the urinary tract or a chronic disease, had a significantly higher frequency of P-fimbriated strains (31/36, 86%) compared to patients without such underlying factors (p less than 0.01). There was no significant difference in clinical parameters or in frequency of P-fimbriated strains between patients with one positive blood culture and those with two or more positive cultures. The high incidence of P-fimbriated Escherichia coli strains in these patients is thought to depend on the ability of such bacteria to cause acute pyelonephritis, which in many cases precedes Escherichia coli bacteremia.

Adhesiveness↗

PubMed1985

Enzyme-linked immunosorbent assay for detection of antibodies to Pseudomonas aeruginosa exoproteins.

Enzyme-linked immunosorbent assays were developed with four purified Pseudomonas aeruginosa extracellular proteins (exotoxin A, elastase, alkaline protease, and phospholipase C) to determine antibody levels in sera from healthy subjects and the serological response in patients colonized or infected with Pseudomonas aeruginosa. Five of 39 burn patients with wounds colonized by Pseudomonas aeruginosa had elevated antibody titers to alkaline protease. Response to the other antigens was found in only a few patients. Pseudomonas aeruginosa infections (septicemia, osteitis, pneumonia etc.) resulted in increased antibody levels to exotoxin A or phospholipase C in 15 of 22 patients. These findings suggest that repeated determinations of antibodies to Pseudomonas aeruginosa exotoxin A and phospholipase C might be used to monitor therapy in certain patients with osteitis and other deep Pseudomonas infections.

ADP Ribose Transferases↗

PubMed1985

IncP-1 R plasmids decrease the serum resistance and the virulence of Pseudomonas aeruginosa.

Pseudomonas aeruginosa strain PAO1 was compared to PAO1 strains containing an IncP-1 R plasmid (RP1, R68, or R68.45) in an experimental mouse burn infection model. All R plasmids tested caused a 10- to 400-fold increase in mean lethal dose (LD50). The decrease in virulence produced by plasmids R68 and R68.45 was significantly greater than the decrease caused by the closely related plasmid RP1. All plasmids also led to an increased sensitivity of strain PAO1 to human serum bactericidal activity. Virulence and serum resistance of strain PAO1 were restored by curing of the entire plasmid R68.45 but not by deletions in the plasmid's transfer gene regions.

Animals↗

PubMed1985

Adherence of Pseudomonas aeruginosa to tracheal epithelial cells of mink. Studies on bacterial hydrophobicity and elastase production.

Pseudomonas aeruginosa strains, producing variable elastase activity, were evaluated for adherence ability to mink tracheal epithelial cells. Attachment was studied in relation to surface hydrophobic properties of bacteria. Elastase production and bacterial hydrophobicity were measured during growth up to 48 hr. A high elastasolytic strain B1 adhered well; it exhibited a mean of 39.0 bacteria per epithelial cell. Adherence of the organisms was not correlated with the degree of hydrophobicity, since more hydrophobic strains do not adhere better. Bacterial surface becomes less hydrophobic during exponential growth-phase (up to 6 h). Hydrophobicity then slightly increases up to 48 h. No correlation between elastase production and changes in surface hydrophobicity was found, since treatment of washed bacteria from either early exponential or later decline-growth phases with different concentrations of elastase did not markedly affect bacterial hydrophobicity. The results indicate that strains with high or active elastase production adhered better than low or inactive elastase-producing strains. Furthermore, bacterial surface hydrophobicity does not seem to play a major role in adherence.

Adhesiveness↗

PubMed1985

Genetic mapping and characterization of Pseudomonas aeruginosa mutants that hyperproduce exoproteins.

We isolated two mutants of Pseudomonas aeruginosa PAO with defective iron uptake. In contrast to the wild-type strain, the mutants produced extracellular protease activity in media containing high concentrations of salts or iron and hyperproduced elastase, staphylolytic enzyme, and exotoxin A in ordinary media (Xch mutants). The mutations were located in the 55' region of the chromosome, between the markers met-9011 and pyrD.

Bacterial Proteins↗

PubMed1985

Pseudomonas cepacia septicemia in patients with burns: report of two cases.

Pseudomonas cepacia has been ascribed to low pathogenicity in man. Within a 10-day period this organism caused 2 cases of septicemia in the Karolinska Hospital burn unit, one with fatal outcome. Both cases were severely burned patients. A serological response to Ps. cepacia was observed in the surviving patient. The blood isolates from the patients showed a very high degree of similarity in biochemical tests, indicating a common origin although the source was not found. The characteristic antibiogram with resistance to aminoglycosides as well as ampicillin and most cephalosporins causes therapeutic problems, since many septicemias of unknown origin are treated with a combination of ampicillin and an aminoglycoside.

Adult↗

PubMed1984

Transient increase of early-onset group B streptococcal septicemia.

Since 1976, all cases of neonatal group B streptococcal (GBS) septicemia/meningitis have been registered at two Swedish University Hospitals. A significant increase in the number of infants contracting early-onset GBS-septicemia was noticed at one clinic in 1981, from 1-3 cases per yr to 8 cases. Six months prior to this increase the number of deliveries increased from about 1500 per yr to nearly 3000 per yr. It is suggested that external factors, e.g., subtle changes in the nursing combined with an extended disadvantage at the ward might influence the development of early-onset GBS septicemia.

Humans↗

PubMed1984

Relation between antibody response to Pseudomonas aeruginosa exoproteins and colonization/infection in patients with cystic fibrosis.

Enzyme-linked immunosorbent assay (ELISA) was used to measure the antibody response to Pseudomonas aeruginosa exotoxin A, elastase, alkaline protease and phospholipase C in patients with cystic fibrosis (CF). Only the chronically colonized patients showed elevated antibody titres to phospholipase C (22/22 patients), alkaline protease (16/22 patients), exotoxin A (15/22 patients) and elastase (5/22 patients). In a few patients where serial specimens were available, rising titres were recorded to all four antigens during periods of active infection. Antibiotic treatment resulted in decrease of titres against all four antigens, but only the anti-exotoxin A and anti-elastase titres decreased to normal levels. Titres to phospholipase C were the least influenced by antibiotic treatment. The results imply different roles for these exoproteins in chronic colonization versus active infection. The levels of P. aeruginosa antibodies to exoproteins could probably be used in monitoring treatment of patients with CF.

ADP Ribose Transferases↗

PubMed1984

Genetic mapping and characterization of Pseudomonas aeruginosa mutants defective in the formation of extracellular proteins.

We isolated 15 mutants of Pseudomonas aeruginosa PAO which were defective in the formation of certain extracellular proteins, such as elastase, staphylolytic enzyme, and lipase ( Xcp mutants). The mutations were mapped on the chromosome by conjugation and transduction. The locations were xcp -1 near 0', with the gene order cys-59- xcp -1- proB , and loci xcp -2, xcp -3, and xcp -31 at 35', with the gene order trpC , D- xcp -3/ xcp -31- xcp -2- argC . Loci xcp -4 and xcp -41 through xcp -44 were cotransducible with proA at 40'; loci xcp -5, xcp -51, xcp -52, and xcp53 were located at 55', with the gene order leu-10- trpF -met-9010- xcp -53- xcp -5/ xcp -51/ xcp+ ++-52, and xcp -6 was located at 65' to 70', between catA and mtu-9002. Nine mutations ( xcp -2, xcp -3, xcp -31, xcp -4, and xcp -41 through xcp -45) caused decreased production of extracellular enzymes. Six strains with mutations xcp -1, xcp -5, xcp -51, xcp -52, xcp -53, and xcp -6 produced cell-bound exoproteins and had defective release mechanisms. The regulation of production of alkaline phosphatase and phospholipase C is different from other exoproteins , such as elastase, but they all seem to share a common release mechanism. Alkaline protease had separate mechanisms for regulation and release, since this protease was found in culture supernatants of all but one of the mutants, and none of the strains had cell-bound enzyme.

Bacterial Proteins↗

PubMed1983

Comparison of two methods of genetic exchange in determination of the genetic locus of the structural gene for Pseudomonas aeruginosa elastase.

A mutation, lasA1, that results in the synthesis of enzymatically inactive elastase protein was mapped by R68.45 plasmid-mediated conjugation and transposon-facilitated recombination to ca. 75 min on the Pseudomonas aeruginosa PAO chromosome. Since immunologically cross-reactive material is produced, the mutation presumably arose within the elastase structural gene.

Chromosome Mapping↗

PubMed1981

Separation and characterization of enterotoxin and two haemolysins from Aeromonas hydrophila.

Aeromonas hydrophila produces two haemolysins, now designated alpha- and beta-haemolysin (formerly aerolysin or cytotoxic protein), and one enterotoxin. These toxins were separated and purified by isoelectric focusing and gel chromatography. Alpha- and beta-haemolysin differ with regard to prerequisites for their elaboration, such as selection of A. hydrophila strains and temperature and time for cultivation. The nature of their lytic effects on erythrocytes and toxic effects on tissue culture cells differs significantly. Alpha- but not beta-haemolysin was inactivated by reducing agents and activated by oxygen, while beta-haemolysin was more resistant than alpha-haemolysin to proteolytic enzymes but was inactivated by crude gangliosides. When separated from the two haemolysins, the enterotoxin gave positive reactions in the rabbit intestinal loop test, the rabbit skin and the adrenal Y1 cell test, though the sensitivity of the Y1 cell was low as compared with cholera toxin and E. coli LT toxin. No cytotoxic effects were obtained in HeLa cells.

Aeromonas↗

PubMed1981

Protection against experimental Pseudomonas aeruginosa infection in mice by active immunization with exotoxin A toxoids.

The immunoprophylactic effect of chemically inactivated Pseudomonas aeruginosa exotoxin A in experimental pseudomonas infections was studied. Exotoxin A toxoids were prepared by Formalin (f-TXD) or glutaraldehyde (g-TXD) treatment. Immunization of mice with three or four doses (10 micrograms each) of f-TXD and the synthetic adjuvant N-acetylmuramyl-L-alanyl-D-isoglutamine (50 micrograms) induced high levels of antiexotoxin A antibodies as measured by passive hemagglutination assay and enzyme-linked immunosorbent assay. Immunization with toxoid alone did not elicit antitoxin. A significant increase in survival time and survival rate (P less than 0.01) was seen in immunized (f-TXD) and in burned and infected mice (50 to 85%) as compared with control mice immunized with formalinized bovine serum albumin (6 to 20%). Virtually 100% survival was obtained when preinfection immunization weas combined with single-dose gentamicin treatment within 24 h of infection. Immunization with g-TXD increased survival time (P less than 0.01) but did not consistently increase survival rate, and the results were not as satisfactory as those with formalinized exotoxin. The data presented indicate that active immunization with formalinized exotoxin A toxoid and adjuvant induced protective immunity to various degrees against infections in mice and could be potentially useful in prophylaxis of P. aeruginosa infections.

ADP Ribose Transferases↗