Age-related acquisition of oral and nasopharyngeal yeast species and stability of colonization in young children

The occurrence and stability of colonization of oral yeast species and stra ins was determined from 40 healthy children during a 22-month follow-up at the ages 2, 6, 12, 18 and 24 months. In addition, salivary samples were obt ained from the mothers at baseline (2 months) to study the role of the moth er as the source of yeasts for the child. Yeasts were recovered at least on ce from 17/40 (43%) children by the age of 2 years. Of the 40 children, 11 (28%) were yeast-positive at multiple sampling occasions. No significant di fferences were found in recovery frequency of yeasts at different ages. Can dida parapsilosis was isolated in 18/33 (55%) yeast-positive samples, and i t predominated (share of positive findings 76%) at ages 12 to 24 months. Th e same yeast species was rarely detected in successive follow-up samples an d thus on species level yeasts were transient colonizers in the developing oral flora of the children. Of the mothers 20/40 (50%) harbored yeasts. Can dida albicans was recovered from 19/20 (95%) of the yeast-positive mothers and C. parapsilosis from none. Only 7/20 (35%) of the mothers with a yeast- positive finding had a yeast-positive child. In 5/7 (71%) of these mother-c hild pairs, both harbored the same yeast species (C. albicans) and in 3/5 ( 60%) of the pairs the AP-PCR profiles of the yeast isolates were identical suggesting possible transmission. In children, significant relationships (F isher's exact-test, P<0.05) were found between recovery of yeasts and use o f pacifier at age over 12 months, eruption of first teeth at age over 6 mon ths, mother cooling the child's food by blowing and mother cleaning the chi ld's pacifier in her own mouth. In mothers, a significant relationship exis ted between recovery of yeasts and use of antibiotics.