Species Diversity and Antifungal Susceptibilities of Oral Yeasts from Patients with Head and Neck Cancer

Abstract

Purpose

To investigate the colonization and susceptibility to antifungal drugs of oral yeasts in head and neck cancer patients in Hainan, China.

Methods

Oral mucosa samples from 211 head and neck cancer patients were collected. Oral yeasts were isolated and identified to species by rDNA ITS sequencing. The susceptibilities of all yeasts to amphotericin B, fluconazole, fluorocytosine, itraconazole, and ketoconazole were determined.

Results

Yeasts were isolated from 124 of the 211 oral swabs. The 124 yeast isolates were classified into following 10 species, from the most frequent to the least frequent, Candida albicans (53.2%), Candida tropicalis (22.6%), Candida krusei (6.5%), Kodamaea ohmeri (5.6%), Candida parapsilosis (4.8%), Hanseniaspora opuntiae (2.4%), Candida metapsilosis (1.6%), Pichia terricola (1.6%), Pichia norvegensis (0.8%), and Trichosporon asahii (0.8%). The overall frequencies of resistance among the yeasts to amphotericin B, fluconazole, flucytosine, itraconazole, and ketoconazole were 4.8%, 8.1%, 16.1%, 9.7%, and 9.7%, respectively. One C. albicans strain and one C. tropicalis strain were tolerant/resistant to all five drugs.

Conclusion

Given the high prevalence of oral yeast colonization in head and neck cancer patients and the observed resistance of certain yeast isolates to the five antifungal drugs, our results suggest that rapid identification and susceptibility testing should be implemented before antifungal treatment is applied among patients with head and neck cancer in Hainan.

Keywords:

• head and neck cancer
• oral yeast
• Candida
• antifungal resistance

Acknowledgments

We thank XIAO Jun, MO Meizi, and WANG Lulu for helping with sample collections.

Abbreviations

rDNA, ribosome deoxyribonucleic acid; ITS, inter-transcribed spacer; YEPD, yeast extract–peptone–dextrose; RNA, ribonucleic acid; PCR, polymerase-chain reaction; CLSI, Clinical Laboratory Standard Institute; R, resistant; I, intermediate; S, susceptible; C. albicans, Candida albicans; C. krusei, Candida krusei; C. metapsilosis, Candida metapsilosis; C. parapsilosis, Candida parapsilosis; C. tropicalis, Candida tropicalis; H. opuntiae, Hanseniaspora opuntiae; K. ohmeri, Kodamaea ohmeri; P. norvegensis, Pichia norvegensis; P. terricola, Pichia terricola; T. asahii, Trichosporon asahii.

Data Sharing Statement

The detailed host demographic information for each individual yeast isolate is available upon request.

Disclosure

We declare that there are no competing financial or other interests associated with this study.