Antifungal Susceptibility Profiling of Candida spp. Isolates Associated with Bloodstream Infection with 9 Antifungal Agents: Surveillance Study in a Medical Center of Northern Taiwan

北台灣某醫學中心血液培養陽性念珠菌分離株對9種抗黴菌藥物的感受性分析

念珠菌菌血症在台灣是發病率和死亡率的重要原因之一。即早使用適當的抗黴菌藥物治療已經證實對病人的治療結果有直接影響。然而，不同的念珠菌種對於抗黴菌藥物會呈現不同的感受性，在暴露藥物後部分分離菌株可能還會產生抗藥性。所以，念珠菌分離株的抗黴菌藥物感受性流行病學調查對於確保及預測抗黴菌治療效果而言很重要。
在110年 5月至 111年 2月間在台北醫學大學市立萬芳醫院總共收集了 60個血流感染的念珠菌分離株，經次培養於含 5%綿羊血的培養皿後，以基質輔助雷射脫附游離飛行質譜儀 (MALDI-TOF MS) 進行菌種鑑定，念珠菌藥物 感受性檢驗套組 (Sensititre Yeast One panels)執行藥物感受性試驗。我們測定所有念珠菌種對每一種抗黴菌藥物的 MIC50及 MIC90，並且採用 CLSI CBP計算各別念珠菌種野生株中具感受性的比例 (S/WT%) 或採用 CLSI ECV計算各別念珠菌種分離株中野生株的比例進行體外感受性調查。菌種分布結果如下: C. albicans 21株 (35.0%), C. parapsilosis 9株 (15.0%), C. tropicalis 13株 (21.7%), C. glabrata 13株 (21.7%)，以及 C. guilliermondii 4株 (6.7%)。 C.albicans, .tropicalis, C.guilliermondi 及C.glabrata分離株是echinocandin類藥物治療的好標的 Fluconazole及Voriconazole 對C. parapsilosis 分離株而言是好的抗黴菌藥物。所有念珠菌種分離株對 Amphotericin B的 MIC值都小於CLSI對各別念珠菌種建立的 ECV值 本藥對於治療念珠菌菌血症是合理的選擇藥物。

Candidemia is an important cause of morbidity and mortality in Taiwan. Early initiation of the appropriate antifungal therapy has been demonstrated to have a direct effect on the patient’s outcome. However, different Candida spp. isolates display distinct susceptibility profiles towards antifungal agents and some of the isolates may became acquired resistance when exposed to antifungals. Therefore, knowledge of the epidemiological surveillance for antifungal susceptibility of Candida isolates is of concern to ensure and predict antifungal therapy outcome is optimized.
In total, 60 Candida spp. isolates associated with bloodstream infection were collected at Taipei Medical University-Wan Fang Hospital between May 2021 and February 2022. All isolates were subcultured on 5% sheep blood agar and the Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) technique was used for the identification of isolates to the species level. Susceptibility tests were carried out using the Sensititre Yeast-One plates. We determined the MICs for both growth inhibition of 50% and 90% of the isolates, for all isolates, at the recommended endpoints and calculated the percentage of S/WT or MICs within CLSI ECV for each antifungal agent to investigate the in vitro susceptibilities of Candida spp. isolates.
The species distribution was as follows: C. albicans 21 (35.0%), C. parapsilosis 9 (15.0%), C. tropicalis 13 (21.7%), C. glabrata 13 (21.7%), and C. guilliermondii 4 (6.7%). C.albicans, C.tropicalis, C.guilliermondi and C.glabrata were regarded as good targets for echinocandin therapy. FCA and VOR were considered good antifungal agents for C. parapsilosis isolates. AMB MICs were, all, within CLSI ECV among Candida spp. isolates, making it a reasonable choice for the treatment of candidemia.