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Sialic acid: a preventable signal for pneumococcal biofilm, colonisation and invasion of the host

Abstract number: P741

Trappetti C., Kadioglu A., Carter M., Iannelli F., Pozzi G., Andrew P.W., Oggioni M.R.

Objectives: The correlation between carbohydrate availability, pneumococcal biofilm, nasopharyngeal colonisation and invasion has been analysed in order to investigate possible signals changing the host microbe equilibrium.

Methods: A series of sugars were used to evaluate their impact on extent of pneumococcal biofilm formation in a mirotiter biofilm assay and in a carriage model in mice. Specificity of effects was controlled by competition experiments using structural sugar analogues both in the in vitro and in vivo assays.

Results: Out of a series of sugars only sialic acid (N-acetylneuraminic acid) enhanced pneumococcal biofilm formation in vitro, at concentrations similar to those of free sialic acid in human saliva. In a carriage model in mice intranasal inoculation of sialic acid significantly increased pneumococcal nasopharyngeal counts and instigated the translocation of pneumococci to the lungs. Both sialic acid dependent phenotypes could be competed by neuraminidase inhibitors DANA, zanamivir and oseltamivir.

Conclusions: The link between levels of free sialic acid on mucosae, colonisation and initiation of invasive disease shows how a host-derived molecule can influence a colonising microbe and highlights a molecular mechanism which explains the epidemiologic correlation between respiratory infections by neuraminidase bearing viruses and bacterial pneumonia. The data provide a new paradigm for the role of a host compound in infectious disease pointing to new treatment strategies.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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