In Vitro Susceptibility of Talaromyces Marneffei In Malaysia: Comparison of Yeast and Mycelial Phases

Abstract

Talaromyces marneffei is an etiologic agent of talaromycosis. It can cause serious complications and death in immunocompromised patients, particularly in acquired immunodeficiency syndrome (AIDS) patients. This infectious disease is endemic in Southeast Asia including Malaysia. To date, published reports on the antifungal susceptibility profile of T. marneffei is very limited. The objective of this study is to determine the minimum inhibitory concentration (MIC) of T. marneffei in yeast and mycelial phases in Malaysia. In the year 2020, 27 clinical strains of T. marneffei were received from various hospitals in Malaysia. The identification was carried out using microscopic, macroscopic and molecular methods. Following that, the susceptibility of each isolate in both yeast and mycelial form to thirteen common antifungals was performed according to the broth microdilution in Clinical & Laboratory Standards Institute (CLSI) M38 method. The antifungals tested were anidulafungin, micafungin sodium, caspofungin diacetate, 5-fluorocytosine, amphotericin B and terbinafine hydrochloride, posaconazole, voriconazole, itraconazole, ketoconazole, ravuconazole, clotrimazole and isavuconazole. The geometric mean of all antifungals other than anidulafungin, micafungin sodium, caspofungin diacetate and 5-fluorocytosine against T. marneffei mould (mycelial) were >2 μg/ml. However, the geometric mean of all antifungals against T. marneffei yeast was <2 μg/ml. Our in vitro data suggests promising activities of amphotericin B, terbinafine hydrochloride, posaconazole, voriconazole, itraconazole, ketoconazole, ravuconazole, clotrimazole and isavuconazole against yeast and mould phases of T. marneffei.