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At least 685 records · Page 38Linked to original sources
PubMed2000

Effect of molecular size on the ability of zwitterionic polysaccharides to stimulate cellular immunity.

The large-molecular-sized zwitterionic capsular polysaccharide of the anaerobe Bacteroides fragilis NCTC 9343, designated polysaccharide (PS) A, stimulates T cell proliferation in vitro and induces T cell-dependent protection against abscess formation in vivo. In the present study, we utilized a modification of a recently developed ozonolytic method for depolymerizing polysaccharides to examine the influence of the molecular size of PS A on cell-mediated immunity. Ozonolysis successfully depolymerized PS A into structurally intact fragments. PS A with average molecular sizes of 129.0 (native), 77.8, 46.9, and 17.1 kDa stimulated CD4+-cell proliferation in vitro to the same degree, whereas the 5.0-kDa fragment was much less stimulatory than the control 129.0-kDa PS A. Rats treated with 129.0-kDa, 46.9-kDa, and 17.1-kDa PS A molecules, but not those treated with the 5.0-kDa molecule, were protected against intraabdominal abscesses induced by challenge with viable B. fragilis. These results demonstrate that a zwitterionic polysaccharide as small as 22 repeating units (88 monosaccharides) elicits a T cell-dependent immune response. These findings clearly distinguish zwitterionic T cell-dependent polysaccharides from T cell-independent polysaccharides and give evidence of the existence of a novel mechanism for a polysaccharide-induced immune response.

Abdominal Abscess↗
PubMed2003

CD4+ T cells mediate abscess formation in intra-abdominal sepsis by an IL-17-dependent mechanism.

Abscess formation associated with intra-abdominal sepsis causes severe morbidity and can be fatal. Previous studies have implicated T cells in the pathogenesis of abscess formation, and we have recently shown that CD4(+) T cells activated in vitro by zwitterionic capsular polysaccharides from abscess-inducing bacteria such as Staphylococcus aureus and Bacteroides fragilis initiate this host response when transferred to naive rats. In this study, we show that mice deficient in alphabetaTCR-bearing T cells or CD4(+) T cells fail to develop abscesses following challenge with B. fragilis or abscess-inducing zwitterionic polysaccharides, compared with CD8(-/-) or wild-type animals. Transfer of CD4(+) T cells from wild-type mice to alphabetaTCR(-/-) animals reconstituted this ability. The induction of abscesses required T cell costimulation via the CD28-B7 pathway, and T cell transfer experiments with STAT4(-/-) and STAT6(-/-) mice demonstrated that this host response is dependent on STAT4 signaling. Significantly higher levels of IL-17, a proinflammatory cytokine produced almost exclusively by activated CD4(+) T cells, were associated with abscess formation in Th2-impaired (STAT6(-/-)) mice, while STAT4(-/-) mice had significantly lower levels of this cytokine than control animals. The formation of abscesses was preceded by an increase in the number of activated CD4(+) T cells in the peritoneal cavity 24 h following bacterial challenge. Confocal laser-scanning microscopy analysis revealed that CD4(+) T cells comprise the abscess wall in these animals and produce IL-17 at this site. Administration of a neutralizing Ab specific for IL-17 prevented abscess formation following bacterial challenge in mice. These data delineate the specific T cell response necessary for the development of intra-abdominal abscesses and underscore the role of IL-17 in this disease process.

Abdominal Abscess↗
PubMed1984

Timed bacteriostatic and bactericidal activities of selected antimicrobial agents against Bacteroides fragilis isolated from clinical specimens.

The activities of selected antimicrobial agents were evaluated for bacteriostatic and bactericidal activities for a large number of clinically obtained strains of Bacteroides fragilis, with special reference to the incubation time of the microbes with the drugs. If the mode of action of a drug is categorized as bactericidal when the ratio of bactericidal concentration/bacteriostatic concentration is low (less than or equal to 4), and as bacteriostatic when high (greater than or equal to 8), during given periods of incubation, then clindamycin, minocycline and chloramphenicol appeared to be bacteriostatic, and cefoxitin, cefmetazole, latamoxef (moxalactam) and metronidazole bactericidal, when the incubation time was brief (6 hours). All these drugs acted bactericidally on most of the test strains, if the time of incubation was prolonged to 24 hours.

Anti-Bacterial Agents↗
PubMed2001

PCR-dot blot hybridization based on the neuraminidase-encoding gene is useful for detection of Bacteroides fragilis.

Bacteroides fragilis is a Gram-negative obligate anaerobe frequently isolated from clinical specimens and sometimes causes severe septicemia in compromised hosts. Increasing interest has been shown in the enterotoxigenicity and drug resistance of B. fragilis in the field of medical microbiology. We previously reported rapid detection of this anaerobe by nested PCR targeting a neuraminidase-encoding gene nanH. In the present study, we synthesized a digoxigenin-labeled oligonucleotide probe, NH1, which is specific for nanH of B. fragilis, and we combined the hybridization assay using NH1 with the nanH-PCR to detect this anaerobe in a bacteremia model mice. In the specificity test, the oligonucleotide probe, NH1, hybridized only to amplification products from B. fragilis. PCR-dot blot hybridization based on nanH enabled detection of cells of B. fragilis in blood samples even when the number was as low as 2 x 10(3) colony-forming units/ml. These findings suggest that PCR-dot blot hybridization targeting nanH is a useful procedure for diagnosis of septicemia caused by B. fragilis when viable cells in blood cannot be detected by the traditional culture techniques.

Animals↗
PubMed2002

[Enterotoxigenic Bacteroides fragilis as a factor in diarrhea].

The etiology of almost half of the diarrheal diseases has not been cleared yet, in spite of modern diagnostic methods. Bacteroides fragilis strains which secrete an enterotoxin are termed as enterotoxigenic B.fragilis (ETBF). These strains are associated with diarrheal diseases in children above 1 year of age and in adults. B. fragilis toxin (BFT) stimulates intestinal secretion and in-vitro cytotoxic response in HT29/C1 cells. Recent studies suggest that BFT is related to inflammatory bowel disease and colon cancer by triggering nuclear activation with potential oncogene expression. In this review, the molecular pathogenesis, epidemiology and laboratory diagnosis of ETBF have been reviewed to focus on ETBF as a diarrheal agent.

Bacteroides Infections↗
PubMed1976

Anaerobic infections in children: a prospective study.

The prevalence and significance of anaerobic infections in patients at St. Louis Children's Hospital were studied prospectively for a one-year period. Blood, selected body fluids, and aspirates obtained from abscesses or areas of cellulitis were cultured using special anaerobic collection and processing techniques. Infected peritoneal fluid from patients with gastrointestinal disease yielded a large proportion of all anaerobic isolates. The types of organisms isolated were common inhabitants of the intestinal tract. Anaerobic organisms were recovered from only 0.75% of all blood cultures; anaerobic bacteremia accounted for 5.8% of all clinically significant bacteremic episodes (8.7% in the neonatal period and 4.8% in children over 1 month of age). Serious anaerobic infections occurred more frequently in the compromised host or in newborn infants than in otherwise healthy children. Since anaerobic organisms cause a small proportion of infectious diseases in a general pediatric population, the cost of refined bacteriologic techniques for the isolation and identification of these organisms is not warranted in most community hospitals. However, such a program should be available in selected tertiary care centers to aid in the management of certain high-risk patients.

Anti-Bacterial Agents↗
PubMed2003

[Two patients with fever, chills and pain in the right upper abdominal quadrant accompanied by hyperbilirubinaemia: pylephlebitis].

Two male patients aged 55 and 77 years, respectively, presented to the casualty department with fever, chills and right abdominal upper quadrant tenderness. They also had hyperbilirubinaemia. Based on CT scan findings and blood cultures yielding Bacteroides fragilis, a diagnosis of pylephlebitis (septic thrombophlebitis of the mesenteric veins and/or the portal vein) was made. This is a condition with a mortality rate of 10-70%. Primary sources such as diverticulitis are often seen in patients with pylephlebitis, in which bacteria are drained by the mesenteric veins and cause a thrombus in the portal system. In the two patients no primary focus was detected. They were treated with intravenous antibiotic therapy followed by oral antibiotics, and were discharged in good health. Pylephlebitis can be complicated by liver abscesses. Treatment consists of broad-spectrum antibiotics which are adjusted based on the blood cultures results. The duration of treatment is between two and six weeks, depending on the presence of liver abscesses. In patients with abscesses that cannot be drained, longer treatment may be indicated.

Abdominal Pain↗
PubMed1992

[Involvement of the heart valves and great vessels in homozygote familial hypercholesterolemia].

Homozygous familial hypercholesterolaemia is characterized by cutaneous xanthoma development from infancy, precocious and accelerated atherosclerosis with clinical signs of ischemic heart disease and frequent involvement of left heart valves resulting in stenosis and/or incompetence. Two cases are described of this condition, both associated with aortic stenosis. In one case mitral incompetence and thromboembolic pulmonary hypertension were also found. The mitral valve is involved in the atherosclerotic process at the level of the cusps. These become thickened and stiff. Aortic stenosis is mainly due to atheromas infiltrating the Valsalva sinuses and the ascending aorta. Pulmonary hypertension, never reported before in this disease, is probably due to concomitant atheromatosis involving the pulmonary artery with secondary fatty embolism.

Aortic Valve Stenosis↗
PubMed1976

Clindamycin: an evaluation of its role in dental patients.

A review of the etiology of orofacial infections, of the pharmacology and spectrum of clindamycin and its associated complications, and a treatment plan for orofacial infections have been presented. On the basis of the data presented, it would seem that except for proved B fragilis infections, clindamycin is not a first-line drug for infections of the orofacial region. There are, however, indications for its use that have been presented. The serious complications associated with its use have also been presented. A high index of suspicion must be maintained regarding the development of these complications if clindaymcin is to be used.

Bacterial Infections↗