First fungemia case due to environmental yeast Wickerhamomyces myanmarensis: detection by multiplex qPCR and antifungal susceptibility.

AIM: Presenting the first clinical case of Wickerhamomyces myanmarensis. PATIENTS & METHODS: Yeast cells were isolated from blood and central venous catheter of a 5.5-year-old male subject. API 20C AUX, MALDI-TOF MS, ITS and LSU rDNA sequencing, and our qPCR assay were used for identification and the MIC values were determined by CLSI M27-A3. RESULTS: ITS and LSU rDNA sequencing identified both isolates as W. myanmarensis, while API 20C AUX and MALDI-TOF MS did not identify them correctly. Our qPCR specifically distinguished W. myanmarensis from W. anomalus. Isolate obtained from blood showed a higher MIC value for fluconazole, voriconazole and posaconazole. CONCLUSION: Utilization of reliable identification tools might reveal the genuine spectrum of opportunistic yeast species.

Unequivocal identification of an underestimated opportunistic yeast species, Cyberlindnera fabianii, and its close relatives using a dual-function PCR and literature review of published cases.

Although Cyberlindnera fabinaii is a rare opportunist yeast species, its ability to cause septicemia, produce biofilm, and rapid acquisition of resistance to fluconazole and voriconazole, reinforced the urge for its identification from its closely related species. Widely used biochemical assays mainly identify Cyberlindnera fabinaii as Cyberlindnera jadinii and Wickerhamomyces anomalus, resulting in underestimation of this yeast in clinical settings. Moreover, the urge for a reliable molecular means of identification remains unsolved for 28 years. In order to unequivocally differentiate Cy. fabianii, Cy. mississipiensis, Cy. jadinii, and W. anomalus, we designed a dual-function multiplex polymerase chain reaction (PCR) assay. Challenging our dual-function multiplex PCR assay with 30 most clinically important yeast species, proved its specificity. Although conventional PCR could differentiate four target species, the real-time PCR counterpart due to Tm overlap misidentified Cy. mississipiensis as Cy. jadinii. Alongside of presenting a comprehensive literature review of published cases of Cy. fabianii from 1990 to 2018, we collected various clinical isolates from Tehran, Shiraz, and Fasa (July 1, 2017, to December 31, 2017) to find a passive relative distribution of these closely-related species in Iran. Subjecting our Iranian collection of yeast isolates to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS and LSU and ITS rDNA sequencing revealed six isolates of Cy. fabianii (central venous catheter n = 2 and vaginal swabs n = 4) and one isolate of Cy. jadinii (vaginal swabs). Due to the use of biochemical assays in global ARTEMIS study, we encourage reidentification of clinical isolates of Cy. jadinii and Cy. jadinii using MALDI-TOF or Sanger sequencing that might lead to correcting the distribution of this fungus.