KHẢO SÁT SỰ NHẠY CẢM CỦA CÁC CHỦNG ASPERGILLUS SPP. VỚI THUỐC KHÁNG NẤM IN VITRO BẰNG KỸ THUẬT VI PHA LOÃNG VÀ E-TEST

Abstract

Objective: Aspergillus infections are a serious medical challenge, particularly in immunocompromised patients. The increasing resistance to antifungal drugs, especially azoles, requires continuous surveillance and evaluation of susceptibility testing methods. This study was conducted to investigate the distribution of Aspergillus species and their susceptibility to antifungal agents isolated at Cho Ray Hospital, as well as to compare the agreement between broth microdilution and E-test methods. Subjects and methods: A cross-sectional descriptive study was conducted on 50 Aspergillus spp. isolates obtained from respiratory specimens at Cho Ray Hospital between October 2024 and August 2025. The isolates were tested for susceptibility to antifungal agents (amphotericin B, caspofungin, voriconazole, itraconazole, posaconazole) using two parallel methods: broth microdilution (Sensititre™ YeastOne™) and E-test. Results: Among the 49 isolates investigated, Aspergillus fumigatus was the most frequently recovered species (31/49, 62.0%), followed by A. flavus (12/49, 24.0%), A. niger (5/49, 10.0%), and A. terreus (1/49, 2.0%). Two A. fumigatus isolates (6.5%) were resistant to voriconazole, and five isolates (16.1%) were classified as non-wild-type with itraconazole by the broth microdilution method. For amphotericin B, one A. fumigatus and two A. niger isolates were identified as non-wild-type. Other species, including A. flavus and A. terreus, were susceptible to all antifungal agents tested. The overall categorical agreement (susceptible/resistant or WT/non-WT) between Sensititre and E-test was high. Nevertheless, some notable discrepancies were observed, particularly with voriconazole and itraconazole in isolates with MICs near the clinical breakpoints. Posaconazole was not applicable for A. fumigatus, and all other isolates were categorized as wild-type. Conclusion: A. fumigatus was the predominant species among the Aspergillus isolates. Although the azole resistance rate was not high, its presence highlights the need for routine surveillance. The E-test showed good agreement with the reference broth microdilution method and may serve as an effective screening tool in clinical practice, but results near resistance thresholds should be confirmed using the standard method.