Abstract
Purpose:
Xylitol is a 5 carbon sugar which is thought to be a metabolic inhibitor of bacterial growth. It is used in the fields of dentistry and otolaryngology for prevention of dental caries and treatment of otitis media. We investigated its possible application as an ophthalmic preservative for contact lenses.
Methods:
In the first experiment 12 contact lens cases were incubated with a solution of 4% LB, 1:500, 1:1000 or 10:10,000 dilutions of a staphylococcus epidermiditis stock solution, and either 1% xylitol or no xylitol. They were incubated overnight and CFU were counted the next day. In the second experiment 6 contact lens cases were incubated with ~100 cfu of staphyloccus epidermitidis, the above solution, and xylitol. 6 control cases had the same solution but without xylitol. They were plated after 7 days and CFU quantified.
Results:
In the first experiment there was here was no significant inhibition of bacterial growth at the 1:500 bacterial concentration (127.3 vs 127 CFU, p = 0.99) and at 1:1000 concentration (44.7 vs 50 CFU, p=0.55). At 1:10,000 dilution of bacteria there was trend towards fewer CFU in the xylitol group, (5.5 vs 3.2 CFU, p=0.07). In the second experiment there was trend towards increased CFU in the xylitol group (133.5 vs 50.2 CFU, p = 0.18).
Conclusions:
Xylitol may be an inhibitor of bacteria when they are in low concentrations. This effect does not appear to be strong. Xylitol may encourage bacterial growth when incubated for longer periods with bacteria, suggesting that bacteria may have regulatory mechanisms to metabolize xylitol.
Keywords: 477 contact lens •
422 antibiotics/antifungals/antiparasitics •
573 keratitis