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.