Antifungal susceptibility of filamentous fungi isolated from sputa of patients with cystic fibrosis in Argentina

CUESTAS ML; LOPEZ DANERI G; POLA S; FINQUELIEVICH JL; SPREJER E; BRITO DEVOTO T; RUBEGLIO E; DAN FRANCO O

Congreso; 15TH INFOCUS; 2017

Filamentous fungi may contribute to the local inflammation and therefore to the progressive deterioration of the lung function in cystic fibrosis (CF) patients. The resistance of Aspergillus and Scedosporium species (the most common moulds isolated from this group of patients) to antifungals is increasingly reported and the knowledge of the local epidemiology and antifungal susceptibility pattern is pivotal to define adequate treatment policies. Aims: to analyze the susceptibility patterns of Aspergillus and Scedosporium species causing fungal infections in CF patients from Argentina.Methods: the in vitro susceptibility patterns of 68 fungal isolates of the genera Aspergillus and Scedosporium recovered from CF patients was evaluated using the classical disk diffusion method on non-supplemented Mueller-Hinton agar plates and by E-test (MIC Test strips, Liofilchem) on RPMI-1640 agar plates. Determinations were made for 4 antifungal drugs: amphotericin B, itraconazole, posaconazole and voriconazole. The interpretation zones and minimum inhibitory concentration (MIC) breakpoints were analyzed according to the Clinical and Laboratory Standards Institute (CLSI) (M51-A document).Results: MICs were above the epidemiological cut-off values for posaconazole and itraconazole in 9.5% of Aspergillus fumigatus; amphotericin B in 43% of Aspergillus terreus strains. All Scedosporium strains were resistant to posaconazole and amphotericine B in both assays. By far the highest susceptibility was obtained in the case of voriconazole, with MIC ranging from 0.032 to 0.75 µg/ml in all cases.Conclusions: The relatively high frequency of itraconazole and posaconazole resistant strains as well as the low susceptibility profile of amphotericine B makes voriconazole best adapted as a first-line treatment of aspergillosis and scedoporiosis in Argentina. Further studies using the M38-A microdilution method should be carried out to confirm these results, despite the high percentaje of agreement with the E-test technique as previously reported by many mycologists.