Interindividual variability and intraindividual stability of oral fungal microbiota over time

Oral microbiota is one of the most complex and diverse microbial communities in the human body. In the present study, we aimed to characterize oral fungi biodiversity and stability over time in a group of healthy participants with good oral health. Oral health and oral fungal microbiota were evaluated in 40 healthy individuals. A follow-up of 10 participants was carried out 28 weeks and 30 weeks after the first sampling. Oral rinse was collected and incubated in a fungal selective medium at 25ºC and 37ºC for 7 days. Fungi were identified based on macro- and microscopic morphology. API/ID32C was used for yeast identification, and molecular techniques were used to identify the most prevalent nonidentified moulds, mainly by sequencing 18S and internally transcribed spacer regions. Moulds were recovered from all participants and yeast from 92.5%. The most frequently isolated fungi were Candida spp., Rhodotorula spp., Penicillium spp., Aspergillus spp., and Cladosporium spp. The oral fungal community presented a high interindividual variability, but the frequency and quantification of each fungal taxon was constant over the 30-week observation period, showing a consistent intraindividual stability over time. The intraindividual stability opposed to interindividual variability may suggest a common and a variable group of fungi in the oral cavity.