Bacterial pathogens induce abscess formation by CD4(+) T-cell activation via the CD28-B7-2 costimulatory pathway. (65/1459)

Abscesses are a classic host response to infection by many pathogenic bacteria. The immunopathogenesis of this tissue response to infection has not been fully elucidated. Previous studies have suggested that T cells are involved in the pathologic process, but the role of these cells remains unclear. To delineate the mechanism by which T cells mediate abscess formation associated with intra-abdominal sepsis, the role of T-cell activation and the contribution of antigen-presenting cells via CD28-B7 costimulation were investigated. T cells activated in vitro by zwitterionic bacterial polysaccharides (Zps) known to induce abscess formation required CD28-B7 costimulation and, when adoptively transferred to the peritoneal cavity of naive rats, promoted abscess formation. Blockade of T-cell activation via the CD28-B7 pathway in animals with CTLA4Ig prevented abscess formation following challenge with different bacterial pathogens, including Staphylococcus aureus, Bacteroides fragilis, and a combination of Enterococcus faecium and Bacteroides distasonis. In contrast, these animals had an increased abscess rate following in vivo T-cell activation via CD28 signaling. Abscess formation in vivo and T-cell activation in vitro required costimulation by B7-2 but not B7-1. These results demonstrate that abscess formation by pathogenic bacteria is under the control of a common effector mechanism that requires T-cell activation via the CD28-B7-2 pathway.  (+info)

67Gallium in 68 consecutive infection searches. (66/1459)

When employed in the study of peripheral infections, 67Ga scanning is sensitive and accurate. When used as a diagnostic tool for suspected abdominal abscesses, it locates and delineates abscesses in somewhat over half the cases. Moreover, the true-negative rate is high and the false-positive rate is acceptably low. Gallium scans should be interpreted with all available clinical information. The coexistence of noeplasm is a problem which at present is not completely resolved.  (+info)

Clinical experience with 99mTc-DMSA (dimercaptosuccinic acid), a new renal-imaging agent. (67/1459)

Results are reported from the clinical evaluation of a new radiopharmaceutical for renal imaging, 99mTc-DMSA (dimercaptosuccinic acid). Sixty-five patients were studied and six of these patients' scintiphotos are illustrated. The physical characteristics of 99mTc and the mercurial-like kinetics of the chelate produced high-resolution scintiphotos of the renal parenchyma in patients of all ages and with a variety of disease entities. The commercial availability of the material in kit form permits its usage in all nuclear medicine facilities.  (+info)

Structural basis of the abscess-modulating polysaccharide A2 from Bacteroides fragilis. (68/1459)

Zwitterionic capsular polysaccharides from pathogenic bacteria have peculiar immunological properties. They are capable of eliciting T-cell proliferation and modulating the course of abscess formation. To understand the molecular basis of this characteristic immune response, we are conducting detailed structure-function studies on these polysaccharides. We have identified, purified, and characterized an abscess-modulating polysaccharide, PS A2, from the clinical strain Bacteroides fragilis 638R. Here, we report the elucidation of both the chemical and three-dimensional structures of PS A2 by NMR spectroscopy, chemical methods, gas chromatography-mass spectrometry, and restrained molecular dynamics calculations. PS A2 consists of a pentasaccharide repeating unit containing mannoheptose, N-acetylmannosamine, 3-acetamido-3,6-dideoxyglucose, 2-amino-4-acetamido-2,4,6-trideoxygalactose, fucose, and 3-hydroxybutanoic acid. PS A2 is zwitterionic and carries one cationic free amine and one anionic carboxylate in each repeating unit. It forms an extended right-handed helix with two repeating units per turn and a pitch of 20 A. Positive and negative charges are exposed on the outer surface of the polymer in a regularly spaced pattern, which renders them easily accessible to other molecules. The helix is characterized by repeated large grooves whose lateral boundaries are occupied by the charges. The three-dimensional structure of PS A2 explicitly suggests mechanisms of interaction between zwitterionic polysaccharides and proteins.  (+info)

Repair of a saccular aortic aneurysm with superficial femoral-popliteal vein in the presence of a pancreatic abscess. (69/1459)

When one is faced with impending rupture, repair of an aortic aneurysm cannot be delayed. In the presence of coexisting intra-abdominal sepsis, traditional therapy would call for aneurysm exclusion and axillofemoral bypass grafting. Consequences of this choice of treatment include limited long-term graft patency and recurrent prosthetic infection. Autogenous deep veins from the lower extremities have demonstrated exceptional patency and resilience to infection when used to replace infected aortic grafts. We now report a case of concomitant open drainage of a pancreatic abscess and repair of a saccular abdominal aortic aneurysm using the superficial femoral-popliteal vein as a conduit.  (+info)

Orbital abscess: management and outcome. (70/1459)

PURPOSE: To discuss the diagnosis, management and outcome of various types of orbital abscess. METHODS: The medical records of 13 patients diagnosed and treated for orbital abscess were reviewed. The sources of infection included: paranasal sinusitis (n = 5), odontogenic origin of infection (n = 4), one each, temporal fossa abscess, palatal abscess, furuncle on the nose, and secondary to retrobulbar injection of steroid. Computed tomographic scans revealed the presence of an abscess in all 13 cases. Associated findings on CT scan included: sinus disease (n = 8), cavernous sinus thrombosis (n = 2) and subdural empyema (n = 2). All patients were treated with intensive, multiple, intravenous antibiotics and early surgical drainage. RESULTS: Purulent material collected surgically from the orbit cultured Staphylococcus aureus (n = 3), two each Pseudomonas aeruginosa, Proteus mirabilis, Acinetobacter species and one each beta-haemolytic Streptococci, Citrobacter frundi and Enterobacter. Final visual acuity was good in 6 patients (6/12-6/6) and no light perception in 6 others. Visual acuity could not be recorded in the infant. The other complications were intracranial abscess (n = 4), cavernous sinus thrombosis (n = 2) and restricted ocular motility (n = 1). CONCLUSIONS: A high index of suspicion is necessary, along with early institution of appropriate diagnostic imaging, and aggressive medical and surgical treatment for a favourable outcome in cases of orbital abscess.  (+info)

Osteomyelitis in children: comparison of hematogenous and secondary osteomyelitis. (71/1459)

SUMMARY: A review of osteomyelitis in 54 patients treated at the Dr. Charles A. Janeway Child Health Centre over a 4-year period revealed equal frequencies of secondary and hematogenous osteomyelitis. Although the clinical picture in patients with hematogenous osteomyelitis was classic, patients with secondary osteomyelitis presented with an altered clinical response. Patients with secondary osteomyelitis have a history of an antecedent puncture wound or an inadequately treated contiguous focus of infection; antistaphylococcal antimicrobial therapy was ineffective for most because gram-negative bacilli were isolated in this group of patients. In contrast to patients with hematogenous osteomyelitis, who frequently respond to intensive antimicrobial therapy, those with secondary osteomyelitis will frequently require surgical intervention to eradicate the infection.  (+info)

Burkholderia pseudomallei--abscess in an unusual site. (72/1459)

Meloidosis in a unusual site has been reported in a child. Complete identification of the organism has been presented.  (+info)