Background: We have recently shown that azole-resistant Aspergillus fumigatus (AR-Af) with an environmental signature is present in Greece (Siopi ECCMID2019). Nevertheless, the prevalence of azole resistance in Greek clinical isolates remains uncertain. We therefore investigated the prevalence of clinical AR-Af in Greece.
Materials/methods: A total of 140 A. fumigatus species complex (SC) strains recovered from respiratory specimens of 133 patients (64 hematological, 16 hospitalized in ICU, 53 other) were collected from 5 centers (4 Athens, 1 Thessaloniki) and were retrospectively tested. Isolates were macro-/micro-scopically identified and were subcultured on Sabouraud+chloramphenicol plates at 48o C to differentiate A. fumigatus sensu stricto (SS). In vitro susceptibility testing of A. fumigatus SC strains to amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC), posaconazole (POS), isavuconazole (ISA), anidulafungin (AFG), caspofungin (CAS) and micafungin (MFG) was performed according to EUCAST E.DEF9.3.1. Isolates exhibiting reduced susceptibility to azoles were subjected to confirmatory molecular identification (White 1990, Balajee 2005) and were further studied for the detection of specific mutations in the cyp51A gene, including its promoter region associated with azole resistance (Mellado 2007).
Results: All isolates grew at 48o C indicating that they belonged to A. fumigatus SS. Antifungal susceptibility patterns among all strains are summarized in Table. In total, all isolates were AMB-susceptible and exhibited echinocandin wild-type phenotypes. POS was the most potent azole in vitro (geometric mean MIC 0.11 mg/L), followed by ITC, VRC and ISA (geometric mean MIC 0.46, 0.59 and 0.70 mg/L, respectively). Overall, 1/140 (0.7%) AR-Af SS from 1/133 (0.8%) patient was detected. Particularly, the isolate was recovered from a pleural fluid culture of an ICU patient, did not have mutations in cyp51A, showed resistance to ITC and POS (MIC >8 and 0.5 mg/L, respectively) and was susceptible to VRC and ISA (MIC 1 mg/L for both drugs).
Conclusions: All clinical A. fumigatus isolates were sensu stricto. We report the detection of an azole-resistant clinical A. fumigatus without cyp51A mutations. The rate of AR-Af in Greece seems to be low (0.7%).
Presenter email address: [email protected]
Full conference title:
- ECCMID 30th (2020)