Molecular characterization of fungal populations on the tongue dorsum of institutionalized elderly adults

OBJECTIVES: To characterize the global composition of oral fungal populations in frail elderly adults and to investigate the relationship with their health status. MATERIALS AND METHODS: We investigated the fungal populations on the tongue dorsum in 291 institutionalized elderly adults by molecular PCR-based techniques using internal transcribed spacer regions of nuclear ribosomal DNA. RESULTS: Quantitative PCR analysis showed that fungi were present on the tongue dorsum of 128 subjects at ≥10(4) CFU per sample, and 35 of them exceeded 10(5) CFU per sample. Length heterogeneity-PCR analysis and nucleotide sequence determinations showed that Candida albicans was most frequently detected in those subjects with fungi at ≥10(4) CFU per sample (105 subjects), followed by Candida dubliniensis (78), Malassezia restricta (57), and Candida tropicalis (45). Statistical analysis revealed that those subjects with ≥10(5) CFU of fungi other than C. albicans per sample had an increased risk of fever (≥7 febrile days per 12 months) compared with subjects with <10(5) CFU per sample, after adjustment for other fever-associated confounding factors. CONCLUSIONS: These data demonstrate that the oral cavity of the elderly is inhabited by a diverse array of fungi not limited to typical Candida species and they suggest that the diversity in distribution is associated with health status.