Antifungal susceptibility patterns among clinical isolates of Aspergillus fumigatus from paediatric cystic fibrosis patients in Greece: a laboratory-based study with focus on azole resistance

Maria Siopi *1, Angeliki Stathi 2, Helen Kirikou 2, Levantia Zachariadou 2, Spyros Pournaras 1, Joseph Meletiadis 1;3

Author address: 

1 Clinical Microbiology Laboratory, “Attikon” University General Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece; 2 Microbiology Department, “Aghia Sophia” Children’s Hospital, Athens, Greece; 3 Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, Netherlands

Abstract: 

Background: Allergic bronchopulmonary aspergillosis is estimated to occur in ~18% of cystic fibrosis (CF) patients in Greece (Armstead 2014). Aspergillus fumigatus species complex (SC) is the predominant mould recovered from respiratory secretions of these patients. The prevalence of azole-resistant A. fumigatus (AR-Af) in CF patients varies greatly between centres and may reach 9% (Seufert 2018). Data on Greek clinical isolates are lacking. We therefore investigated the occurrence of AR-Af in Greek paediatric CF patients.

Materials/methods: A total of 55 A. fumigatus SC strains recovered from sputum samples of 37 paediatric CF patients (14 male-23 female) during 2008-2009 (32 isolates-21 patients) and 2017-2019 (23 isolates-16 patients) were retrospectively tested. Isolates were macro-/micro-scopically identified to SC level. A. fumigatus sensu stricto (SS) were presumptively identified based on growth at 48o C. 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. Azole resistance was also tested with the agar dilution method (EUCAST E.Def10.1) and gradient concentration strips (MTS).

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, followed by ITC, ISA and VRC. Overall, 2/55 (3.6%) pan-AR-Af SS (ITC, VRC, ISA, POS MIC >8, 4, 8, 1 mg/L, respectively) were detected. The pan-AR-Af phenotype was also found with the agar dilution method (visible growth on azole-containing plates) and MTS (ITC, VRC, ISA, POS MIC >32, 2, 2-4, 0.75-1 mg/L, respectively). Particularly, these isolates were recovered from subsequent specimens (August/December 2018) of 1/37 (2.7%) 16-year-old male patient without prior azole exposure. Confirmatory molecular identification of the pan-ARAf isolates and detection of specific mutations in the cyp51A associated with azole resistance are under investigation.

Conclusions: This is the first study to document the presence of AR-Af SS in Greek CF patients emphasizing the importance of antifungal susceptibility testing of A. fumigatus. Further surveillance multicentre studies are required to estimate the exact prevalence of AR-Af.

Presenter email address: [email protected]

2020

abstract No: 

5558

Full conference title: 

European Congress of Clinical Microbiology and Infectious Diseases 2020
    • ECCMID 30th (2020)