Infection and Drug Resistance (Jun 2019)
Identification and antifungal susceptibility profiles of Kodamaea ohmeri based on a seven-year multicenter surveillance study
Abstract
Menglan Zhou,1–3 Shuying Yu,1–3 Timothy Kudinha,4 Meng Xiao,1,3 He Wang,1,3 Yingchun Xu,1,3 Hongmei Zhao51Department of Clinical Laboratory, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, People’s Republic of China; 2Graduate School, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, People’s Republic of China; 3Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100730, People’s Republic of China; 4Central West Pathology Laboratory, Charles Sturt University, Orange, New South Wales, Australia; 5Department of Clinical Laboratory, The People’s Hospital of Liaoning Province, Liaoning 110016, People’s Republic of ChinaBackground: Kodamaea ohmeri has been a rare fungal pathogen in the past decades but is now becoming more common in various invasive fungal diseases, with high mortality. There are limited data on the occurrence and distribution of K. ohmeri.Methods: Sixty-two K. ohmeri isolates collected from 24 hospitals in China over a 7-year period were studied. Performance of three phenotypic methods in the identification of this organism was assessed against a gold standard, 26S rDNA sequencing. Original identification results submitted by the participating local hospitals were reviewed. The Sensititre YeastOne YO10 (SYY) was evaluated in determining the in vitro antifungal susceptibilities using standard broth microdilution method (BMD) as a reference, and essential agreement (EA) was calculated.Results: Accurate species identification was achieved in 82.3% and 96.8% of the cases by Vitek 2 Compact and Vitek mass spectrometry (MS), respectively. For Bruker MS, 12.9% and 96.8% of the isolates were correctly identified to species level using the direct transfer and protein extraction methods, respectively. Only 29 (46.8%) isolates were initially correctly identified as K. ohmeri by the local hospitals. The highest misidentification rate (100%, 16/16) was observed in CHROMagar. According to BMD, the highest MIC90 was seen in fluconazole (8 μg/mL), followed by 1 μg/mL for micafungin, caspofungin, 5-fluorocytosine, and amphotericin B, 0.5 μg/mL for itraconazole, 0.25 μg/mL for posaconazole and voriconazole. Significant differences in EAs for different drugs were observed, ranging from 95.2% for amphotericin B to 22.6% for itraconazole between SYY and BMD.Conclusion: Our study emphasizes the need for accurate identification of clinical K. ohmeri isolates and the importance of validating antifungal susceptibility by standard BMD.Keywords: Kodamaea ohmeri, identification, antifungal susceptibility profiles, invasive fungal disease, surveillance
