JAC Advance Access originally published online on June 9, 2004
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Journal of Antimicrobial Chemotherapy 2004 54(1):225-228; doi:10.1093/jac/dkh302
JAC vol.54 no.1 © The British Society for Antimicrobial Chemotherapy 2004; all rights reserved.
Ultrastructure of Streptococcus pneumoniae after exposure to xylitol
1 Department of Pediatrics, University of Oulu, PO Box 5000, FIN-90014, Oulu; 2 Department of Pathology, Biocenter Oulu, Oulu; 3 National Public Health Institute, Oulu; 4 Clinical Microbiology Laboratory, Oulu University Hospital, Oulu, Finland
* Corresponding author. Tel: +358-8-3152011; Fax: +358-8-3155559; Email: matti.uhari{at}oulu.fi
Objectives: Xylitol is a sugar alcohol which reduces the growth of Streptococcus pneumoniae and the adherence of pneumococci and Haemophilus influenzae to nasopharyngeal cells. Xylitol prevents acute otitis media but does not decrease nasopharyngeal carriage of pneumococci. We hypothesized that xylitol could affect the surface structures of viable pneumococci, which would further explain the mechanism of action of xylitol in preventing acute otitis media.
Methods: We exposed five strains of pneumococci to 0.5%–5% xylitol, 5% glucose, 5% fructose and 5% sorbitol or control medium (brain heart infusion) for 0.5–2 h and examined the ultrastructure of bacteria by electron microscopy.
Results: The cell wall of pneumococci became more diffuse, the polysaccharide capsule became ragged and the proportion of damaged pneumococci increased after exposure to xylitol for 2 h, but not after exposure to other sugars or control medium. The phenotype of all pneumococcal strains was opaque before xylitol exposure and became almost transparent both in xylitol and in control medium during the experiment.
Conclusions: This study demonstrates further that xylitol has a harmful effect on pneumococci. The observed changes in the polysaccharide capsule and the cell wall of pneumococci could affect the adherence and virulence of pneumococci, explaining the good clinical efficacy of xylitol in the prevention of acute otitis media.
Keywords: electron microscopy , bacterial polysaccharides , otitis media , pathogenicity
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  P. Kurola, T. Tapiainen, T. Kaijalainen, M. Uhari, and A. Saukkoriipi Xylitol and capsular gene expression in Streptococcus pneumoniae J. Med. Microbiol., November 1, 2009; 58(11): 1470 - 1473. [Abstract] [Full Text] [PDF]
|
|