Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology

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pISSN 2288-0585 eISSN 2288-6850

Species Distribution and Antifungal Susceptibility of Yeasts Isolated from Ear Specimens

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2019 December, Volume 22, Issue 4, pages 81-89.

https://doi.org/10.5145/ACM.2019.22.4.81

Species Distribution and Antifungal Susceptibility of Yeasts Isolated from Ear Specimens

Yong Jun Kwon, Seung A Byun, Min Ji Choi, Eun Jeong Won, Soo Hyun Kim, Jong Hee Shin

Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea

Abstract

Background: Candida auris was first isolated from the ears of Japanese and Korean patients. However, the prevalence of yeast isolates from ear cultures and their antifungal susceptibility profiles in these nations remain unclear.

Methods: We assessed yeast isolates recovered from ear cultures from a university hospital in Korea over a 4-year period from January 2014 to December 2017. Species identification was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and/or sequence analysis. Antifungal minimal inhibitory concentrations (MICs) were determined using the broth microdilution method of the Clinical and Laboratory Standards Institute.

Results: Among 81 non-duplicate isolates from ear cultures, Cadida parapsilosis was the most frequently detected yeast species (34.6%), followed by C. auris (28.4%), Candida metapsilosis (9.9%), Candida orthopsilosis (8.6%), Candida albicans (7.4%), and others (11.1%). The MICs of the isolates were 0.125 to >64 μg/mL, ≤0.03 to 4 μg/mL, 0.25 to 1 μg/mL, 0.125 to 1 μg/mL, and ≤0.03 to 2 μg/mL for fluconazole, voriconazole, amphotericin B, caspofungin, and micafungin, respectively. Of the 81 isolates, 44.4% (36/81) showed decreased susceptibility to fluconazole (MIC ≥4 μg/mL). Of the 23 C. auris isolates, 19 (82.6%) had a fluconazole MIC of ≥32 μg/mL. None of the isolates showed resistance to amphotericin B or echinocandins. Most of these patients suffered from chronic otitis media (84%).

Conclusion: Candida parapsilosis complex and C. auris were the yeast species identified most frequently from ear cultures and they exhibited a high rate of fluconazole non-susceptibility, particularly C. auris. (Ann Clin Microbiol 2019;22:81-89)

Keywords

Antifungal resistance, Candida auris, Ear, Fluconazole, Yeast