Antifungal susceptibility profile of Aspergillus species from patients with increased risk for aspergillosis

Abstract

Aspergillosis is the most common fungal infection caused by molds, especially in high-risk patients. The treatment of these diseases is based on the use of polyene and azole antifungal drugs. Resistance rates of Aspergillus species to antifungal drugs vary widely across medical centers around the world. Antifungal susceptibility testing of Aspergillus species to antifungal agents could provide useful information for clinicians to make decision regarding the patient therapy. The aim of the study was to evaluate the antifungal susceptibility profile of Aspergillus species towards amphotericin B, itraconazole, voriconazole and caspofungin, isolated from patients with increased risk for aspergillosis. During a 2-year period, clinical specimens from 125 patients divided into 4 groups according to clinical diagnosis and EORTC/MSG criteria, were analysed at the Institute of Microbiology and parasitology, Faculty of Medicine, Skopje, Republic of North Macedonia. These groups included patients with primary immune deficiency, critically ill patients treated in intensive care units, patients with chronic aspergillosis and cystic fibrosis. All specimens (from respiratory tract and blood culture) were investigated with conventional mycological methods, by inoculation of specimens on media for support of fungal growth. Identification of Aspergillus was performed with macroscopic analysis of mold colonies and additional microscopic analysis of their conidia with lactophenol blue method. E-test strips of voriconazole, itraconazole, amphotericin B and caspofungin (AB bioMerieux, France) were used for determination of the antifungal susceptibility profile of Aspergillus species. Seventy-one isolates of Aspergillus species were confirmed in our patients. Four isolates of A.fumigatus (5.6%) were confirmed in blood cultures, from patients with primary immune deficiencies, and 67 isolates (94.4%) originated from respiratory specimens from patients with different underlying diseases. A.flavus was identified in 11 patients and A.terreus in 3 patients. Resistance to amphotericin B was detected in 6 isolates (2 isolates of A.fumigatus, 1 isolate of A.flavus and 3 isolates of A.terreus). Only one isolate of A.fumigatus showed resistance to itraconazole. All isolates of Aspergillus species were sensitive to voriconazole and caspofungin. In vitro antifungal susceptibility testing with E-test demonstrated resistance to amphotericin B in 6 isolates of Aspergillus species. Only one isolate of A.fumigatus was resistant to itraconazole. All isolates of Aspergillus species showed sensitivity to voriconazole and caspofungin. Antifungal susceptibility testing of Aspergillus species with E-test provides useful information for clinicians for appropriate choice of antifungal agents for treatment of aspergillosis. Keywords: Aspergillus, mold, infection, susceptibility, E-test