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Biomedical subjects

D L Kasper

Publications and source records attributed to D L Kasper.

At least 181 records · Page 10Linked to original sources
PubMed1979

Mouse protection test for group B Streptococcus type III.

The mouse model has been used previously for the study of protection against challenge with strains of group B Streptococcus types Ia, Ib, and Ic, but investigators have not yet been successful in causing lethal disease when type III strains are inoculated. In this study, six clinical isolates belonging to serotype III were lethal in seven-week-old outbred albino mice; the 50% lethal dose (LD50) for mice tested ranged from 1.8 x 10(4) to 4.6 x 10(6). In contrast, a laboratory prototype strain of serotype III was not lethal. The lethality observed with this protection test depended on both the volume of the inoculum given and the medium in which the streptococci were suspended. LD50 values decreased as the volume of the inoculum, given intraperitoneally, increased, up to a volume of 1.5 ml. Hyperimmune rabbit antiserum to a clinical isolate of type III protected mice against an estimated 90% lethal dose of the isolate. Normal rabbit serum and heterologous antisera, except for one of two antisera to type Ia organisms, were not protective. Absorption of type III antiserum with whole organisms of serotype III or with purified, type III-specific polysaccharide inhibited protection of mice against type III organisms.

Absorption↗
PubMed1979

Protective efficacy of immunization with capsular antigen against experimental infection with Bacteroides fragilis.

The protective efficacy afforded by immunization with the capsular antigen of Bacteroides fragilis against abscess formation and bacteremia due to this organism was studied in an experimental rat model of intraabdominal sepsis. Of unimmunized animals, animals immunized with methylated bovine serum albumin and complete Freund's adjuvant, and animals immunized with lipopolysaccharide of Bacteroides thetaiotaomicron, greater than 90% developed abscesses when challenged intraperitoneally with strains of B. fragilis or Bacteroides distasonis (given with an enterococcus) or with the cecal contents of meat-fed rats. In contrast, animals immunized with B. fragilis capsular polysaccharide, given with or without methylated bovine serum albumin and complete Freund's adjuvant, and animals immunized with the outer membrane of B. fragilis strain 23745 were protected to a significant degree from abscesses caused by challenge with B. fragilis or B. distasonis. Such immunization had no overall effect on the development of abscesses in animals challenged with the entire cecal contents of meat-fed rats; however, B. fragilis was eliminated from the abscesses of these animals. Animals immunized with the capsular polysaccharide were protected from early B. fragilis bacteremia.

Abscess↗
PubMed1979

Opsonic specificity of human antibody to the type III polysaccharide of group B Streptococcus.

The functional significance of vaccine-induced or naturally acquired antibody to the capsular polysaccharide of type III group B Streptococcus was determined in human sera by means of an opsonophagocytic assay. Sera containing a sufficient concentration of type-specific antibody and endogenous serum complement caused a significant reduction (greater than 1 log10) in colony-forming units for each of 22 type III clinical isolates after incubation for 40 min. In contrast, serum with a very low concentration of antibody (0.4 micrograms/ml) killed only one isolate. Absorption of serum containing vaccine-induced antibody with purified native type III polysaccharide decreased opsonophagocytosis by a mean of 1.2 log10 for 11 selected type III strains. These results indicate a lack of major antigenic differences among a wide spectrum of type III strains, since bactericidal activity of human serum is uniformly observed in the presence of complement and sufficient concentrations of antibody to the type III polysaccharide.

Absorption↗
PubMed1979

Detection of anticapsular antibodies to Bacteroides asaccharolyticus in serum from rabbits and humans by use of an enzyme-linked immunosorbent assay.

A sensitive serologic test, the enzyme-linked immunosorbent assay (ELISA), was used to detect serum IgG antibodies directed specifically to a capsular antigen of Bacteroides asaccharolyticus (previously known as Bacteroides melaninogenicus subspecies asaccharolyticus). Anticapsular IgG was measured in 30 specimens of rabbit serum after the animals were immunized with whole B. asaccharolyticus, the two subspecies of B. melaninogenicus, and several other bacterial species. Species-specific anticapsular IgG was demonstrated (P less than 0.001). Levels of anticapsular IgG greater than control levels were likewise detected in serum from two humans, including one patient who had periodontitis and from whom B. asaccharolyticus was isolated, and a laboratory worker who had extensive exposure over a two-year period to B. asaccharolyticus. The ELISA was found to be a relatively simple, sensitive tool for measurement of serum IgG. Its application to detection of immunoglobulins of other classes, including secretory IgA, is anticipated, provided adequate standardization methods are used.

Animals↗
PubMed1979

The cell envelope of the Legionnaires' disease bacterium. Morphologic and biochemical characteristics.

We studied the cell-envelope structure of the Legionnaires' disease (LD) bacterium by electron microscopy and biochemical assays. There were apparent differences in cell structure by electron microscopy using two different prefixation methods. Organisms prefixed with gluteraldehyde had a single surrounding membrane. The typical two-membrane structure of gram-negative bacteria, however, was observed after prefixation with a combination of gluteraldehyde, formalin, and creosol. The cell wall (peptidoglycan) was seen in electron micrographs of plasmolyzed bacteria and in papain-digested cells. Both cytoplasmic and outer membranes were separated by differential centrifugation of spheroplast sonicates followed by sucrose density gradient ultracentrifugation. We identified each membrane by characteristic enzyme activity (cytoplasmic membrane) and 2-keto-3-deoxyoctonate content (outer membrane).

Bacteria↗
PubMed1978

A review. Lessons from an animal model of intra-abdominal sepsis.

Intra-abdominal sepsis that involves multiple aerobic and anaerobic bacteria derived from the colonic flora was studied in Wistar rats to determine the relative roles of various microbial species. The rats challenged with pooled colonic contents showed a biphasic disease. Initially, there was acute peritonitis, Escherichia coli bacteremia, and high mortality. In rats that survived this acute peritonitis stage, intra-abdominal abscesses developed, and anaerobic bacteria were the preponderant organisms. Subsequent experiments showed that antibiotics directed against coliforms prevented mortality, whereas agents active against anaerobes reduced the incidence of abscesses. Challenges with Escherichia coli alone produced bacteremia and death, whereas pure cultures of Bacteroides fragilis caused intra-abdominal abscesses. These observations suggest that both coliforms and anaerobes are important pathogens in intra-abdominal sepsis, although the different types of microbes appear to play distinctive roles in the sequence of pathological events.

Abdomen↗
PubMed1978

Quantitative determination of the serum antibody response to the capsular polysaccharide of Bacteroides fragilis subspecies fragilis in women with pelvic inflammatory disease.

The antibody response to the capsular polysaccharide of Bacteroides fragilis subspecies fragilis in women with acute pelvic inflammatory disease was quantitated using a sensitive radioactive antigen-binding assay. Antibody detected by this technique correlated highly with antibody measured by quantitative precipitin analysis (r = 0.99). Paired acute- and convalescent-phase sera obtained from women from whom B. fragilis subspecies fragilis was isolated by culdocentesis showed significantly greater changes in antibody concentration than corresponding sera obtained from women with gonococcal or nongonococcal pelvic inflammatory disease when B. fragilis subspecies fragilis was not isolated from the cul-de-sac. These data indicate that the steady state of immunity to this capsular antigen is perturbed in patients with acute nongonococcal pelvic inflammatory disease from whom this organism can be cultured. This finding may indicate that B. fragilis can play a significant role in acute pelvic inflammatory disease and can be involved early in the infectious process.

Acute Disease↗
PubMed1978

Identification of a subspecies-specific capsular antigen from Bacteroides melaninogenicus subspecies asaccharolyticus by immunofluorescence and electron microscopy.

An indirect fluorescent antibody test was developed with the use of hyperimmune rabbit antiserum to a purified capsular polysaccharide of Bacteroides melaninogenicus subspecies asaccharolyticus. All of 23 strains of B. melaninogenicus subspecies asaccharolyticus were fluorescence-positive in this test. All 11 strains of Bacteroides melaninogenicus subspecies intermedius tested and three strains of Bacteroides melaninogenicus subspecies melaninogenicus were fluorescence-negative. Thirty-one strains of other bacterial species were also fluorescence-negative. The indirect fluorescent antibody test demonstrated the presence of a subspecies-specific capsular antigen from B. melaninogenicus subspecies asaccharolyticus. The capsular antigen was further demonstrated by electron microscopy with ruthenium red, a polysaccharide-staining material.

Animals↗
PubMed1978

Adherence of Bacteroides fragilis in vivo.

The ability of the encapsulated species Bacteroides fragilis to adhere to rat peritoneal mesothelium was compared to the adherence of unecapsulated strains of Bacteroides (B. distasonis, B. vulgatus, B. thetaiotaomicron, B. ovatus, and B. "other"). Adherence was assayed by attaching plexiglas plates containing 8-mm holes to the peritoneal mesothelium of anesthetized rats. Cell suspension (0.25 ml) was incubated in each well, after which the suspension was aspirated, and a 4-mm punch biopsy was removed. Viable organisms adhering to the biopsy specimen were enumerated by plate count following washing of the biopsy tissue. It was found that B. fragilis adhered significantly better to mesothelial tissue (10(3.00) colony-forming units per biopsy) than unencapsulated species of Bacteroides (10(1.07) colony-forming units per biopsy). This effect was not due to differential oxygen sensitivity of the various inocula. Immunization of rats with capsular polysaccharide did not demonstrate decrease in the adherence of B. fragilis; however, preincubation of the mesothelium with purified capsular polysaccharide resulted in a substantial reduction in adherence. These results indicate that B. fragilis adheres to rat peritoneal mesothelium better than unencapsulated species and suggests that the capsular polysaccharide of B. fragilis plays some role in this increased adherence.

Animals↗
PubMed1978

Immunogenicity of polysaccharides from type III, group B Streptococcus.

The immunogenicity and safety of two polysaccharides isolated from type III, group B Streptococcus, were tested in adults selected for existing low concentrations of natural antibody to the capsular polysaccharide of this organism. Both vaccine preparations (trichloroacetic acid and EDTA) were found to lack pyrogenicity and toxicity for experimental animals. A single 50-microgram subcutaneous injection of either polysaccharide in human subjects elicited significant increase in antibody concentration in immunized compared with control individuals receiving phosphate-buffered saline. Antibody responses were maximal by 2 wk and remained at 21 wk after immunization. Vaccine-induced antibody was primarily of the IgG class. Of the two vaccines, the larger molecular size polysaccharide was significantly more immunogenic. Although no systemic reactions were recorded, mild transient local reactions occurred in 45% of vaccinees.

Animals↗
PubMed1977

Bactericidal antibody in genital infection due to Neisseria gonorrhoeae.

An assay of bactericidial antibody has been developed to study the host response to infection with Neisseria gonorrhoeae. This test for antibody was performed on the sera of women who were exposed to N. gonorrhoeae but who did not become infected, of patients with various types of genital infection with N. gonorrhoeae, and of a small number of individuals with no history of gonorrhea. Antibody was found in the sera of less than 31% of men and women with uncomplicated gonococcal infection. Prolonged mucosal infection with the gonococcus (greater than 33 days) correlated with the presence of bactericidal antibody. Bactericidal antibody was not detected in 95% of the specimens of acute-phase serum obtained from women with gonococcal pelvic inflammatory disease. The convalescent-phase sera of 70% of women with clinically severe pelvic inflammatory disease showed a rise in titer of bactericidal antibody to the infecting strain of N. gonorrhoeae, whereas only 11% of the convalescent-phase sera of women with mild or moderately severe disease showed a similar rise.

Antibodies, Bacterial↗
PubMed1977

Purification and immunochemical characterization of the outer membrane complex of Bacteroides melaninogenicus subspecies asaccharolyticus.

Morphologic study of Bacteroides melaninogenicus subspecies asaccharolyticus by electron microscopy disclosed the presence of a capsule and a cell wall structure otherwise typical of a gram-negative organism. An outer membrane complex was isolated with use of gentle methods. Relative purity of the preparation was confirmed by electron microscopy and by the formation of a single band in a sucrose density gradient. Gel chromatography was used for separation of the major components of the membrane. Antigenicity of the first component, a protein-polysaccharide complex, which cross-reacted with antiserum to another strain of the same subspecies. This component probably represents the capsular antigen and may prove to be the basis for serogrouping. The second membrane fraction differed chemically from the first fraction and represents the lipopolysaccharide component of the outer membrane. Notably, this component lacks 2-keto-3-deoxyoctonate, one of the backbone sugars of aerobic, gram-negative lipopolysaccharides.

Antigens, Bacterial↗
PubMed1977

Isolation and identification of encapsulated strains of Bacteroides fragilis.

One hundred three clinical isolates of Bacteroides fragilis were identified during a two-year period. Most of these isolates were strains of B. fragilis subspecies fragilis, which constitutes a minor component of the fecal flora in comparison with the other subspecies of B. fragilis. By use of several techniques for demonstration of capsules, it was found that only B. fragilis strains classified as subspecies fragilis were encapsulated. An indirect immunofluorescence assay was developed for identification of clinical isolates possessing capsular material that was immunologically similar to that found in the reference strain of B. fragilis subspecies fragilis. All strains examined that were classified as subspecies fragilis were positive in this assay for the capsular material, whereas strains of the other subspecies were negative. This tests represents a rapid and sensitive means of identifying the most prevalent anaerobic gram-negative bacillus involved in human infections. The capsular polysaccharide of B. fragilis subspecies fragilis is a unique factor associated with the predominant subspecies of B. fragilis isolated from clinical material.

Antigens, Bacterial↗
PubMed1977

The capsular polysaccharide of Bacteroides fragilis as a virulence factor: comparison of the pathogenic potential of encapsulated and unencapsulated strains.

The pathogenic potentials of encapsulated and unencapsulated strains of Bacteroides fragilis were compared by use of a rat model of intraabdominal sepsis. Implantation of encapsulated B. fragilis alone resulted in abscesses in most recipients, whereas unencapsulated strains seldom produced this effect unless they were combined with another organism. Implants of heat-killed, encapsulated B. fragilis also resulted in abscess formation. Subsequent experiments suggested that the abscess-potentiating ability of encapsulated B. fragilis is related to the capsular polysaccharide. Implantation of 200 microgram of the purified capsular material alone or in conjuction with unencapsulated strains caused abscess formation in a majority of animals. Comparable results were not obtained with capsular polysaccharide from Escherichia coli O7:K1(L)"NM or with heat-killed Streptococcus pneumoniae type III. The capsular polysaccharide of B. fragilis appears to potentiate abscess formation and may represent a virulence factor for this species.

Abscess↗
PubMed1977

Clindamycin-associated colitis due to a toxin-producing species of Clostridium in hamsters.

Clindamycin-associated enterocolitis in hamsters was studied to detect and characterize a transmissible agent. It was found that the disease could be transferred by cecal contents and filtrates of cecal contents (pore size of filter, 0.02 micron) obtained from animals after administration of clindamycin. Subsequent work showed that enterocolitis could be produced with broth cultures of a species of Clostridium recovered from cecal contents of animals with clindamycin-induced disease. The cell-free supernatant of this strain also caused enterocolitis. Cecal contents from animals with clindamycin-induced disease incubated with gas gangrene antitoxin failed to cause intestinal lesions. These experiments indicate that clindamycin-associated colitis in hamsters is due to a clindamycin-resistant, toxin-producing strain of Clostridium.

Animals↗
PubMed1977

Quantitative determination of the antibody response to the capsular polysaccharide of Bacteroides fragilis in an animal model of intraabdominal abscess formation.

The humoral antibody response to the capsular polysaccharide of Bacteroides fragilis was quantitated in an animal model of intraabdominal abscess formation using a sensitive quantitative radioactive antigen-binding assay. Antibody detected by this technique correlated highly with antibody measured by quantitative precipitin analysis (r = 0.943). Animals infected with encapsulated B. fragilis develop high levels of circulating serum antibody to the capsular polysaccharide. This antibody can be induced by implantation of live organisms, heat-killed organisms, heterologous strains of B. fragilis, and various outer membrane components that contain the capsular antigen. The immunogenicity of the capsular polysaccharide could be enhanced when administered as part of the outer membrane or when not separated from outer membrane proteins. Evidence of an antibody response to this capsular polysaccharide offers support for the demonstrated pathogenic potential of encapsulated B. fragilis.

Abdomen↗