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L Dall

Publications and source records attributed to L Dall.

At least 19 recordsLinked to original sources
PubMed1995

Contribution of the host to test results in assays of Staphylococcus epidermidis.

From two human populations (one pediatric and one adult), clinically diagnosed with Staphylococcus epidermidis (S. epidermidis) sepsis of similar severity, bacteria were isolated from pre-antibiotic blood samples and evaluated for virulence. The LD50 of the bacteria in a mouse model was performed, with evaluation of animals dying acutely following intravenous S. epidermidis administration. More simple assays of virulence were also performed, including bacterial adherence to a fibrin clot and carbohydrate specific lectin binding. The eight pediatric-host S. epidermidis isolates required a significantly larger dose to produce lethality in dosed animals (LD50) when compared to the 20 adult-host S. epidermidis isolates. The fibrin clot assay, a test that has corroborated bacterial virulence in endocarditis models, did not differentiate the groups: all but one of the 28 isolates were well above the adherence seen with the ATCC control, suggesting endocarditis-producing potential. Glycocalyx (slime) from eight of the more virulent isolates showed reactivity with a glucose-specific biotinylated lectin which was lacking in other isolates. Necropsy of mice dying at 12 hr showed S. epidermidis strain differences in specific organ effects. Overall, this study demonstrates the utility of the LD50 to provide a highly sensitive quantification of bacterial virulence. Necropsy of test animals dying acutely has showed an apparent organ tropism of some of these isolates which are usually considered harmless commensals.

Adult↗
PubMed1994

Bacterial characterization in Staphylococcus epidermidis septicemia.

An analysis of the in vitro characteristics of Staphylococcus epidermidis strains isolated from patients with true S. epidermidis septicemia was undertaken. From a potential population of 921 cultures from adult patients with coagulase-negative bacteremia, highly defined selective criteria limited the population to 20 patients with S. epidermidis sepsis, from whose blood cultures the study organisms were isolated. Another population of 11 S. epidermidis blood isolates, clinically determined to be contaminants, were tested as a control group. In vitro assays performed on all isolates included slime quantification, hydrophobicity, surface hexoses, and capsule presence. Murine spleen phagocytosis of intravenously administered isolates was measured in vivo. The assayed quantity of cell-associated bacterial hexose sugars positively correlated with organism virulence to the host (p = 0.02). This bacterial population was also low in slime but varied as to the presence of capsule and ease of phagocytosis. Permanent catheter-bearing patients' bacteria were somewhat more hydrophobic (p = 0.07). We conclude that in vitro assays can differentiate bacteremic cultures from contaminants and that the characteristic that best relates to host toxicity in these S. epidermidis isolates was bacterial cell surface-associated carbohydrate.

Adult↗
PubMed1990

Clindamycin effect on glycocalyx production in experimental viridans streptococcal endocarditis.

Abundant glycocalyx production by viridans streptococci in the rabbit model of endocarditis has been associated with delayed antimicrobial sterilization. Enzymatic digestion of the glycocalyx with dextranase enhances antibiotic activity. The effect of clindamycin (30 mg/kg, subcutaneous, three times daily) was studied in rabbits with experimental aortic valve endocarditis caused by high glycocalyx-producing viridans streptococci. Animals receiving clindamycin had smaller vegetations that were sterilized more quickly than did controls or animals receiving penicillin or dextranase alone (P less than .001). Penicillin plus dextranase treatment allowed greater bacterial killing than penicillin alone and did not differ significantly from clindamycin treatment. Electron micrographs revealed markedly less cell-adherent glycocalyx on organisms grown in vitro treated with clindamycin versus penicillin and controls. It is hypothesized that clindamycin inhibits glycocalyx production in vivo, allowing better antimicrobial penetration in the infected cardiac vegetation.

Animals↗
PubMed1989

Quantitative assay of glycocalyx produced by viridans group streptococci that cause endocarditis.

A quantitative method to determine glycocalyx production by strains of viridans group streptococci from patients with endocarditis is presented. There is good correlation between this new tryptophan quantitative assay and qualitative assays employing polysaccharide stains (ruthenium red, periodic acid-Schiff, and Cellufluor) or the Molisch test. The quantification of the glycocalyx production in glucose substrate in vitro by viridans group streptococci correlates with the size of cardiac vegetation and ease of antimicrobial sterilization in experimental endocarditis. The relationship of in vitro quantification of glycocalyx to maintenance of infection, morbidity of infection, and antimicrobial treatment is discussed.

Animals↗
PubMed1989

Septicaemia in a granulocytopenic patient caused by Corynebacterium striatum.

A 64 year old woman with metastatic endometrial carcinoma was admitted to the hospital after three grand mal seizures. Blood cultures yielded Corynebacterium striatum. The patient responded to parenteral ampicillin therapy. This is believed to be the first case of sepsis caused by this organism.

Agranulocytosis↗
PubMed1988

Influence of underlying disease process on the utility of cellulitis needle aspirates.

A prospective microbiological evaluation of 87 patients with acute cellulitis was performed. Adult patients with cellulitis with diabetes mellitus or malignant disorders had a greater frequency of positive cultures. Qualitative leukocyte disorders associated with these underlying disease states was hypothesized as a contributing factor to this higher yield.

Acute Disease↗
PubMed1987

Infective endocarditis of a bicuspid aortic valve caused by Hansenula anomala.

Infective endocarditis due to Hansenula anomala developed on a bicuspid aortic valve in a 40-year-old man. H. anomala, an ascomycetous yeast, may be a member of the normal flora of the throat and alimentary tract in humans but has not been previously known to be pathogenic in humans. A past history of intravenous drug use may have contributed to the development of disease in this patient.

Adult↗
PubMed1987

Enzymatic modification of glycocalyx in the treatment of experimental endocarditis due to viridans streptococci.

The presence of abundant surface polysaccharide, or glycocalyx, on viridans streptococci has been associated with failure to eradicate the organism from experimental cardiac vegetations during penicillin treatment. The role of glycocalyx in retarding sterilization was tested by in vivo administration of dextranase, an endohydrolase that attacks internally situated alpha (1-6) linkages. Dextranase and penicillin, either singly or in combination, were used to treat experimental endocarditis. After two days of therapy, 100% of animals treated with penicillin or dextranase alone had infected vegetations, whereas only 25% treated with penicillin and dextranase had infected vegetations (P less than .01). After five days of therapy, 100% of the animals treated with penicillin had infected vegetations, versus none that were treated with penicillin and dextranase (P less than .01). We conclude that glycocalyx acts to retard antibiotic activity in vegetations and that partial enzymatic digestion of the glycocalyx facilitates penicillin sterilization of the infected valve.

Animals↗
PubMed1985

Effects of exopolysaccharide production by viridans streptococci on penicillin therapy of experimental endocarditis.

The influence of exopolysaccharide production by viridans streptococci on penicillin therapy of endocarditis was studied in rabbits with experimental aortic-valve endocarditis. Animals were first infected with penicillin-susceptible streptococci known to produce varying amounts of exopolysaccharide in cardiac vegetations. Treatment with procaine penicillin, 300,000 U every 12 hr, was begun one to two days after infection. After five days of therapy, animals infected with Streptococcus sanguis II and Streptococcus morbillorum, both vigorous exopolysaccharide producers, continued to have infected vegetations, while animals infected with Streptococcus salivarius and a different Streptococcus sanguis II, both deficient in exopolysaccharide production, had sterile vegetations. These findings indicate that failure to eradicate streptococci from vegetations correlates with exopolysaccharide production and that this property may be important in determining outcome of therapy.

Animals↗
PubMed1984

Escherichia vulneris: isolation and treatment.

We have described two cases of Escherichia vulneris wound infections resistant to ampicillin given orally, but susceptible to higher blood levels obtainable by parenchymal administration.

Adult↗
PubMed1984

Exopolysaccharide production by viridans streptococci in experimental endocarditis.

Light and electron microscopy with histochemical staining were used to estimate exopolysaccharide production by strains of viridans streptococci recovered from patients with endocarditis. Six strains were selected for study because they represented a wide range of in vitro polysaccharide production. By light microscopy, there was good agreement between three polysaccharide stains (ruthenium red, periodic acid-Schiff and calcifluor white) in the amount of glycocalyx produced, which ranged from minimal (0 to 1+) to maximal amounts (4+). Two strains selected for minimal (strain 1) and maximal (strain 6) in vitro exopolysaccharide production were studied after we used them to experimentally infect cardiac vegetations. Glycocalyx could be demonstrated surrounding organisms in cardiac vegetations, and the relative amounts produced were similar to those seen in vitro. Vegetations formed by glycocalyx-producing strains were also larger than those formed by glycocalyx-deficient strains. Viridans group streptococci which produce exopolysaccharide in vitro also do so within cardiac vegetations. The relationship of exopolysaccharide production to maintenance of endocardial infection is discussed.

Animals↗