EFFECT OF XYLITOL ON GROWTH OF NASOPHARYNGEAL BACTERIA IN-VITRO

Xylitol is known to reduce caries by inhibiting the growth of Streptoc occus mutans. We hypothesized that xylitol could also affect the growt h of other nasopharyngeal bacterial flora, which could be important wh en considering respiratory infections caused by these bacteria. We stu died this in vitro by adding xylitol to the medium and observed that 1 and 5% xylitol reduced markedly the growth of alpha-hemolytic strepto cocci, including S. pneumoniae. It reduced slightly the growth of beta -hemolytic streptococci but not that of Haemophilus influenzae or Mora xella catarrhalis. The inhibitory growth pattern was similar to that p reviously seen with S. mutans, which may indicate a similarity in the enzymatic processing of five-carbon sugars such as xylitol. This sugar alcohol is a widely used sweetener, and the concentrations used in ou r experiments are easily achieved in the oral cavity. If xylitol reduc es the growth of S. pneumoniae in the nasopharynx, it could also reduc e the carriage of this pathogen and thus have clinical significance in the prevention of pneumococcal diseases.