The effect of storage in liquid nitrogen on the isolation of oral yeasts in human saliva

Stimulated whole saliva samples were collected from a group of 127 6-yr-old schoolchildren. Each sample was divided into three parts. The first two, one of which contained added glycerol, were immediately frozen in liquid nitrogen and stored at -196 °C for 2 months. The third part was transferred to the laboratory and plated on selective medium for yeasts. Colony counts of the frozen and non-frozen samples were then compared. Statistical analysis showed a highly significant correlation between the counts for frozen and unfrozen samples. A high (40.1%) prevalence of yeast carriers was found, and Candida albicans was the most frequently recovered yeast.