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Query: UMLS:C0014118 (endocarditis)
 15,629 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Staphylococcus epidermidis is a major pathogen in early prosthetic valve endocarditis and cerebrospinal fluid shunt infections. Approximately 10 to 15% of hospital isolates are methicillin resistant. Ten clinically significant isolates of the latter were collected for antibiotic studies in vitro and in an experimental infection in animals. Time-kill studies of five strains showed gentamicin to be the single most effective antibiotic; however, dwarf colony variants emerged as survivors with two of these strains when challenged with gentamicin alone. The addition of a second antibiotic to gentamicin did not significantly improve the bactericidal rate but prevented the emergence of variant strains. A blood culture isolate of methicillin-resistant S. epidermidis combined with 5% hog gastric mucin was used to establish an experimental intraperitoneal infection in mice. Neither methicillin nor nafcillin treatment reduced mortality below that of untreated animals. Cephalothin treatment delayed early mortality but did not diminish overall mortality. Gentamicin was the most effective single antibiotic, and gentamicin in combination with vancomycin was the most effective regimen overall. The combination of rifampin plus vancomycin was as effective as gentamicin alone. The combinations of cephalothin or nafcillin with gentamicin and cephalothin with vancomycin demonstrated antagonism. The antagonism was not due to multiple injections or drug-drug inactivation.
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PMID:Antibiotic activity in vitro against methicillin-resistant Staphylococcus epidermidis and therapy of an experimental infection. 25 21

The production of glycosidase and protease activities, which may play a role in the degradation of human glycoproteins, by Streptococcus oralis strains isolated from endocarditis, septicaemia or the oral cavity was investigated with a range of fluorogenic substrates. The pH optima of the proteases ranged from 6.0 to 9.3 and the pH optima for the glycosidases were lower (4.5-6.0), although the pH range over which both groups of enzymes acted was broad. Growth in a minimal medium supplemented with glucose resulted in repression of glycosidase activities and elevated proteolytic activity. Bacteria from cultures supplemented with porcine gastric mucin (PGM), a model glycoprotein, exhibited higher levels of glycosidase activity, while proteolytic activity was suppressed and glycoprotein-derived monosaccharides were transported at significantly higher rates than those observed for cells grown in media with glucose. PGM-derived cells also exhibited high levels of N-acetylneuraminate pyruvate-lyase, the first intracellular enzyme in the pathway of sialic acid catabolism. Taken together, these data indicate that S. oralis strains produce a range of proteolytic and glycosidic enzymes that may play a role in the degradation of host-derived glycoproteins.
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PMID:Effect of mucin and glucose on proteolytic and glycosidic activities of Streptococcus oralis. 863 57

Nine strains of Streptococcus oralis, isolated from blood cultures of patients with infective endocarditis or from the oral cavity as part of the normal flora, were examined for their ability to elaborate sialidase (neuraminidase) and N-acetylglucosaminidase, enzymes which are involved in the degradation of glycoproteins. Both glycosidases were induced when bacteria were grown in a minimal medium supplemented with porcine gastric mucin, a model glycoprotein, and repressed when growth occurred in the presence of glucose. Cell-free extracts mucin-grown cultures expressed elevated levels of N-acetylneuraminate pyruvate-lyase (the first intracellular enzyme in the pathway of N-acetylneuraminate catabolism), N-acetylglucosamine (glcNAc)-6-phosphate deacetylase and glucosamine-6-phosphate deaminase (enzymes involved in the intracellular catabolism of GlcNAc 6-phosphate); activity of each of these intracellular enzymes was markedly repressed when bacteria were grown in media supplemented with alpha 1-acid glycoprotein, a major component of human plasma. Cells from these cultures expressed high levels of sialidase, N-acetylglucosaminidase, and the intracellular enzymes involved in the catabolism of N-acetyl-sugars released by action of these glycosidases. High-resolution 1H-NMR spectroscopy of spent culture supernatants revealed that sialic acid and GlcNAc residues of the molecularly mobile oligosaccharide side-chains of alpha 1-acid glycoprotein had been hydrolysed and the released sugars internalized by the bacteria. These data indicate that S. oralis has the ability to hydrolyse constituents of oligosaccharide side-chains of host-derived glycoproteins and to utilize simultaneously these released carbohydrates. The biochemical characteristics induced by the growth of S. oralis on glycoproteins may play a role in the survival and persistence of these bacteria at the infection site in vivo.
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PMID:Metabolism of glycoprotein-derived sialic acid and N-acetylglucosamine by Streptococcus oralis. 870 62