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

Streptococcus oralis has emerged as one of the most important organisms of the viridans streptococcus group in terms of infections and is recognised as an agent of infective endocarditis and, in immunocompromised patients, septicaemia. The mechanisms by which this organism proliferates in vivo are unknown. However, host-derived sialic acids -- including N-acetylneuraminic acid (NeuNAc) which is present in serum and cell-associated glycoproteins -- are a potential source of fermentable carbohydrate for bacterial proliferation, especially for sialidase-producing bacteria, including S. oralis. To further elucidate the role of NeuNAc in supporting growth, this study determined the ability of S. oralis strain AR3 (isolated from a patient with infective endocarditis) to transport NeuNAc and characterised the transport system. The transport of [14C]-labelled NeuNAc into S. oralis was monitored and this transport system was induced by growth of the bacteria in the presence of the N-acetylated sugars NeuNAc, N-acetylglucosamine and N-acetylmannosamine. The transport system followed typical Michaelis-Menten kinetics, with a Km of 21.0 microM and a Vmax of 2.65 nmoles of NeuNAc transported/min/mg of dry cell mass. NeuNAc transport was inhibited by the presence of exogenous N-glycolylneuraminic acid, a related sialic acid. Chlorhexidine, NaF and 2,4-dinitrophenol were potent inhibitors of the transport system, suggesting that the uptake of NeuNAc occurs via a proton motive force-dependent permease system. This is the first report of the mechanism by which NeuNAc transport occurs in pathogenic streptococci. This transport process may have relevance to the acquisition of a source of fermentable carbohydrate and thus bacterial proliferation in vivo.
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PMID:N-acetylneuraminic acid transport by Streptococcus oralis strain AR3. 1050 80

Oral health is integrally linked to overall well-being. This article describes a research program focused on the contribution of poor oral health to systemic illness. Initial investigations examined factors related to streptococcal virulence that were important in dental caries and endocarditis and led to development of immunization strategies in animal models to reduce risk of endocarditis. Clinical investigations related to critically ill adults began with descriptive and observational studies that established the importance of dental plaque in development of ventilator-associated pneumonia (VAP) and examined existing nursing practices in oral care. Subsequent intervention studies sponsored by the National Institutes of Health (NIH) to test oral care protocols in critically ill adults have built on that foundation. The group's first NIH-funded randomized clinical trial tested the effects of toothbrushing and use of chlorhexidine in reducing risk of VAP in critically ill adults and showed that VAP was reduced by topical application of chlorhexidine initiated after intubation, although toothbrushing did not reduce VAP. The study had a rapid and dramatic effect on clinical practice. Results of the study were published in September 2009 in the American Journal of Critical Care, and in May 2010, the Institute for Health-care Improvement updated the recommendations for the care of patients receiving mechanical ventilation (the ventilator bundle) to include daily oral care with chlorhexidine, referencing the results of that study as evidence for the change. Chlorhexidine is now the standard of care for adults receiving mechanical ventilation. Because the effects of chlorhexidine after intubation were so beneficial, a second recently completed NIH-funded randomized clinical trial investigated the impact of chlorhexidine applied before intubation compared with after intubation. Currently a large randomized clinical trial is being launched to determine the optimal frequency of toothbrushing for critically ill patients receiving mechanical ventilation in an effort to maximize oral health benefits while minimizing systemic risks. The importance of collaboration and mentoring in building nursing science is discussed. Future directions for research also are explored.
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PMID:Oral health: something to smile about! 2498 68