Search PubMed⌕ Search

Biomedical subjects

W M Scheld

Publications and source records attributed to W M Scheld.

At least 73 records · Page 4Linked to original sources
PubMed1991

Developments in the pathogenesis, diagnosis and treatment of nosocomial pneumonia.

Despite recent progress in the prevention and therapy of hospital acquired infections, nosocomial pneumonia remains an important problem in critically ill patients. Nosocomial pneumonia develops in five to ten patients per 1,000 admissions and has a mortality rate of 20 to 50 per cent. This review updates three areas that have been the subject of investigation in recent years: pathogenesis, especially the role of gastric colonization with gram-negative bacilli in retrograde pharyngeal spread; diagnosis, particularly by bronchoalveolar lavage and the protected specimen brush during bronchoscopy, and therapy with extended spectrum penicillins, third generation cephalosporins, imipenem, aztreonam and quinolones.

Anti-Bacterial Agents↗
PubMed1990

Bacterial meningitis: recent advances in pathophysiology and treatment.

PURPOSE: To review recent advances in the understanding of pathogenic and pathophysiologic mechanisms underlying bacterial meningitis that may lead to the development of adjunctive strategies for treating this disorder. DATA IDENTIFICATION: Studies published from 1975 to 1989 were identified using Index Medicus and by reviewing the bibliographies of identified articles. STUDY SELECTION: We reviewed the experimental and human studies evaluating pathogenesis, pathophysiology, and antimicrobial treatment of bacterial meningitis, as well as those reviews that have contributed to our understanding of meningitis. DATA EXTRACTION: We evaluated the data on the pathogenesis, pathophysiology, and treatment of bacterial meningitis and considered in depth the information from animal models that may have potentially important applications in the treatment of human disease. RESULTS OF DATA SYNTHESIS: Penicillin and ampicillin remain the drugs of choice for meningitis caused by Streptococcus pneumoniae and Neisseria meningitidis. The third-generation cephalosporins have revolutionized the treatment of gram-negative bacillary meningitis; one such agent, ceftazidime, is also useful for treating Pseudomonas aeruginosa meningitis. Modification of subarachnoid space inflammation by anti-inflammatory agents may lessen many of the pathophysiologic consequences of bacterial meningitis. A recent study of adjunctive dexamethasone therapy in infants and children with bacterial meningitis showed that the incidence of long-term neurologic sequelae was lower in the corticosteroid group. CONCLUSION: Future therapy for bacterial meningitis will use recent developments in the understanding of pathogenic and pathophysiologic mechanisms underlying this disease. Additional studies using monoclonal antibodies against specific virulence factors and investigations into the production of inflammatory cytokines in response to bacterial cell products may lead to additional treatments that decrease the high morbidity and mortality in patients with bacterial meningitis.

Animals↗
PubMed1990

Isolation and characterization of endothelial cells from bovine cerebral arteries.

For our laboratory's investigation into the role of the endothelial cells in vasospasm following subarachnoid hemorrhage and in inflammatory diseases, we found it necessary to devise a modified method of cell culture, which would be appropriate for studying human endothelial cells from lobectomized brain. We report our techniques to increase cell harvest and ensure reproducibility, our method of culturing endothelial cells from bovine major cerebral arteries, and our morphologic and immunocytochemical characterization of these cells. To increase the harvest of endothelial cells, the blood cells were washed from the lumen of the major cerebral arteries at the slaughterhouse and a modified reversed vessel technique was employed. The monolayer of cultured endothelial cells displayed a cobblestone appearance when it reached confluency and transmission electron microscopy revealed junctional complexes and interdigitation of cytoplasm at Passages 10 and 17. The cells stained positively for Factor VIII-related antigen at Passages 3, 5, 7, 10, and 15. Also the cells metabolized acetylated low-density lipoprotein at Passage 8. To determine the purify of the cultured endothelial cells, an immunocytochemical study of the cytoskeleton was performed on Passage 5 cells using either rhodamine-phalloidin or antibodies against smooth muscle myosin, desmin, and vimentin.

Actins↗
PubMed1990

Treating systemic fungal infections in AIDS patients. Prolonging life against the odds.

Fungal infections have become one of the major causes of death among immunocompromised patients, particularly patients with AIDS. Accurate and quick diagnosis is difficult; therefore, empirical therapy is often necessary. This scenario is complicated by the fact that most antifungal agents are toxic at the doses used or relatively ineffective against deep-seated mycoses. Because the population of AIDS patients is increasing, physicians will be faced more often with the management of systemic fungal infections. Despite the current bleak prognosis for these patients, several new antigen detection tests are being developed and triazole agents are proving to be effective and less toxic than their predecessors. Many cases of systemic mycoses do result in mortality, but appropriate treatment can both prolong life and improve its quality.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Aztreonam.

Aztreonam, the first commercially available monobactam, has a wide range of activity against aerobic gram-negative bacilli. It can be administered two to three hours daily because its half-life is 1.6 to 2 hours. Excellent blood and tissue concentrations are attained. The MIC of aztreonam against most Enterobacteriaceae is less than or equal to 2 micrograms/ml and against P aeruginosa less than or equal to 16 micrograms g/ml. Aztreonam has been used in a wide array of infections of the urinary tract and respiratory tract, blood, intra-abdominal and gynecologic infections and infections of the skin, bones and joints. As empiric therapy, aztreonam is usually combined with another antimicrobial agent active against anaerobes and/or aerobic gram-positive cocci until culture results are available. One exception is empiric therapy for gram-negative urinary tract infections in which aztreonam can be used initially as monotherapy against susceptible gram-negative pathogens. In general, the efficacy of aztreonam is equal or superior to that of the aminoglycosides. Adverse reactions to aztreonam are unusual, and it as been shown to be a poor hapten, permitting its administration to patients with proven allergy to the penicillins and cephalosporins. Aztreonam is a useful addition to the available antibiotics for treatment of gram-negative infections.

Aztreonam↗
PubMed1990

Septic sacroiliitis due to Proteus mirabilis.

This case demonstrates the difficulty frequently encountered in making an early diagnosis of septic sacroiliitis. The proper use of appropriate laboratory tests and radiologic examinations can narrow the differential diagnosis significantly, with confirmation resting on culture results. Appropriate antibiotic therapy will depend on the organism isolated. When confronted by the typical clinical findings and supporting ancillary data of septic sacroiliitis, the physician should consider the possibility of an unusual organism such as Proteus mirabilis and should direct antibiotic therapy accordingly.

Adolescent↗
PubMed1990

Staphylococcus aureus ventriculitis treated with single-dose intraventricular vancomycin or daptomycin (LY146032): bacterial and antibiotic kinetics in hydrocephalic rabbits.

Vancomycin and a new antibiotic, daptomycin (LY146032), were tested in vitro and in vivo against Staphylococcus aureus. In vivo tests were performed with rabbits with kaolin-induced hydrocephalus. Five groups of rabbits were studied: untreated ventriculitis, intraventricular vancomycin only, and ventriculitis treated with intraventricular vancomycin (30 micrograms or 120 micrograms) or daptomycin (7.5 micrograms). Results of this study were as follows. (i) S. aureus demonstrated static growth in cerebrospinal fluid in vitro and in ventriculitis at a maximum titer of 10(5) to 10(6) CFU/ml. (ii) In vitro time kill curves in cerebrospinal fluid matched those in vivo. (iii) Single-dose intraventricular vancomycin did not lower S. aureus concentrations over 8 h, whereas daptomycin did. (iv) Ventriculitis did not significantly alter the clearance of intraventricular vancomycin. (v) Intraventricular half-lives were approximately 2.8 h (maximum) for vancomycin and 4.5 h for daptomycin. (vi) Vancomycin was detectable in the periventricular white matter only in the presence of ventriculitis. Daptomycin was also detectable in the periventricular white matter of rabbits with ventriculitis, but in amounts too small to quantitate. We concluded that daptomycin achieved greater bactericidal activity, more rapid killing kinetics, and a longer half-life in the ventricle than vancomycin did in this model.

Animals↗
PubMed1990

Pathogenesis and pathophysiology of meningitis.

Advances in the understanding of the pathogenesis and pathophysiology of meningitis have occurred primarily through the use of experimental animal models. These models have proven to be particularly valuable in experimental bacterial meningitis, focusing on the bacterial virulence factors responsible for the initiation of infections, CNS invasion, and induction of SAS inflammation. Recent studies have examined the formation of host inflammatory cytokines in response to these virulence factors. These cytokines may be responsible for many of the pathophysiologic consequences of bacterial meningitis (eg. increased BBB permeability, cerebral edema, and increased intracranial pressure). Meningitis due to C. neoformans occurs most commonly in patients with defects in cell-mediated immunity (eg, AIDS), and the depletion of T helper cells in AIDS patients may allow unrestricted cryptococcal growth. Viral meningitis is an illness of low prevalence when compared with the overall occurrence of viral infections at other sites. CNS infection usually occurs by means of traversal across barriers that normally exclude viral invasion of the CNS, primarily through hematogenous dissemination from initial sites of infection. These advances in the pathogenesis and pathophysiology of bacterial, fungal, and viral meningitis may lead to the development of innovative treatment strategies for these disorders.

Animals↗
PubMed1990

Bacterial meningitis in adults.

Bacterial meningitis continues to be an important cause of morbidity and mortality despite the availability of effective bactericidal antibiotics. Penicillin or ampicillin remains the drug of choice for meningitis caused by Streptococcus pneumoniae and Neisseria meningitidis. The third generation cephalosporins have revolutionized the treatment of gram-negative meningitis. Future therapy for bacterial meningitis will use recent developments in the understanding of pathogenic and pathophysiologic mechanisms underlying this disease.

Adult↗
PubMed1989

Comparative evaluation of cefuroxime axetil and cefaclor for treatment of acute bacterial maxillary sinusitis.

Cefuroxime axetil, a new beta-lactamase-stable cephalosporin, was compared with cefaclor for the treatment of acute bacterial maxillary sinusitis in 106 adult patients. Direct sinus aspirations for quantitative bacterial culture were done for all patients before treatment; aspiration was repeated for most patients after treatment. Pretreatment sinus aspirates were positive for 63 of 134 sampled sinuses. Of specimens yielding at least 10(4) CFU/mL, Haemophilus influenzae (38%) and Streptococcus pneumoniae (37%) were the most common pathogens. Ten (42%) of 24 strains of H influenzae, 2 (40%) of 5 Haemophilus parainfluenzae, and all 3 isolates (60%) of Branhamella catarrhalis produced beta-lactamase. Cefuroxime axetil, 250 mg twice a day, was compared with cefaclor, 500 mg three times a day. Among culture-positive sinuses, bacteriologic cure was achieved in 36 (95%) of 38 sinuses and 15 (71%) of 21 sinuses treated with cefuroxime axetil and cefaclor, respectively. The overall frequencies of adverse events were similar between drugs, although cefuroxime axetil was associated with more frequent diarrhea. Cefuroxime axetil was an effective therapy for the treatment of acute bacterial maxillary sinusitis in adults.

Acute Disease↗
PubMed1989

Haemophilus influenzae outer membrane vesicle-induced blood-brain barrier permeability during experimental meningitis.

Haemophilus influenzae type b (Hib) lipopolysaccharide (LPS) may be present in the cerebrospinal fluid largely as part of outer membrane vesicles (OMV), which could possibly alter its activity. Similar to inoculation of purified Hib LPS, intracisternal inoculation of Hib OMV into adult rats resulted in dose- and time-dependent increases in blood-brain barrier permeability. Polymyxin B, but not an oligosaccharide-specific monoclonal antibody, significantly inhibited the activity of Hib OMV. No change in blood-brain barrier permeability occurred in leukopenic rats inoculated with Hib OMV. Hib OMV was as active as purified Hib LPS on a weight basis and therefore appears to be a relevant vehicle for the delivery of LPS during meningitis.

Animals↗
PubMed1989

Applications of therapy in animal models to bacterial infection in human disease.

Animal models have proven to be invaluable in bridging the gap between in vitro susceptibility testing of an antibiotic and anticipating results obtained in clinical studies. Variables such as antibiotic concentration, inoculum of organism, and pharmacokinetic parameters of the drug can be carefully controlled to provide information about the principles of treating infectious diseases as well as an evaluation of specific antimicrobial agents. End points of treatment can be precisely defined (that is, CSF sterility in meningitis, vegetation counts of bacteria in endocarditis) to allow a quantitative evaluation of a new antibiotic. However, it is important to realize that there may be differences in disease pathogenesis and antibiotic pharmacokinetics between experimental infections in animal models and infections in humans. Therefore, results in animal models should be interpreted with caution and compared with results obtained with antimicrobial regimens in clinical studies. Perhaps one of the most useful features of animal models is suggesting which antimicrobials would not be expected to be of therapeutic benefit in man.

Animals↗