Effect of xylitol and other carbon sources on Streptococcus pneumoniae biofilm formation and gene expression in vitro.

Xylitol inhibits the growth of Streptococcus pneumoniae. In clinical trials, xylitol decreased the occurrence of acute otitis media in day-care children, but did not decrease nasopharyngeal carriage of pneumococci. We hypothesized that xylitol inhibits biofilm formation of pneumococci, and measured biofilm formation and gene expression levels of the capsule gene cpsB and two other genes: autolysin encoding gene lytA and competence gene comA in different growth media in vitro.

Presence of capsular locus genes in immunochemically identified encapsulated and unencapsulated Streptococcus pneumoniae sputum isolates obtained from elderly patients with acute lower respiratory tract infection.

The principal virulence factor of Streptococcus pneumoniae is capsular polysaccharide, and encapsulated pneumococci are more common causes of disease than unencapsulated strains. This study analysed the presence of capsular genes in 59 pneumococcal isolates using two PCR methods targeted at the cpsA and cpsB genes of the capsular biosynthesis locus. The PCR method targeted at the cpsB gene, reported to be essential for encapsulation, was developed in this study.

Xylitol and capsular gene expression in Streptococcus pneumoniae.

Xylitol is a sugar alcohol that inhibits the growth and adherence of Streptococcus pneumoniae. In clinical trials, xylitol has been shown to decrease the occurrence of acute otitis media in day-care children but did not decrease nasopharyngeal carriage of the pneumococci. It has also been shown that xylitol affects the ultrastructure of the pneumococcal capsule.