In Vitro Activity of Antifungal Drugs against a Global Collection of 28 Clinical and Environmental Exserohilum Species Isolates

Ref ID: 19271

Author:

J. F. Meis, H. Madrid, I. Breuker, F. Hagen, G. S. De Hoog, A. Chowdhary

Author address:

Canisius-Wilhelmina Hosp., Nijmegen, NETHERLANDS

Full conference title:

53rd Interscience Conference on Antimicrobial Agents and Chemotherapy

Date: 10 September 2014

Abstract:

Background: Exserohilum species are common environmental moulds which have recently been implicated in a large outbreak of iatrogenic meningitis in the USA. Previously these moulds were rarely regarded as human pathogens therefore in vitro antifungal susceptibility data of these emerging moulds is scarce. Methods: A total of 28 clinical and environmental isolates of Exserohilum including 13 known species obtained from the CBS-KNAW Fungal Biodiversity Centre, Netherlands and VP Chest Institute, India were studied for in vitro susceptibility to antifungals according to CLSI guidelines. Identities of isolates were re-confirmed using AFLP fingerprinting and ITS sequencing. Results: Molecular identification revealed Exserohilum rostratum represented 28.5% (n=8) of isolates, and remaining species comprised one or two isolates of E. antillanum, E. gedarefense, E. heteropogonicola, E. holmii, E. curvatum, E. neoregeliae, E. pedicellatum, E. prolatum, and E. fusiforme. MIC90s of amphotericin B (0.5 μg/ml), posaconazole (0.5 μg/ml), and itraconazole (0.5 μg/ml) revealed excellent activity among all of the species. In contrast, higher MIC90s of voriconazole (2 μg/ml), isavuconazole (4 μg/ml ) and
fluconazole(>64 μg/ml ) were observed. The
echinocandins, micafungin and caspofungin showed similar
MEC90s (2 μg /ml). E. rostratum MIC ranges were as
follows: amphotericin B (0.063-1 μg/ml), posaconazole
(0.125-0.5 μg/ml), itraconazole (0.125-0.5 μg/ml),
voriconazole (0.5-2 μg/ml), isavuconazole (1-8 μg/ml )
and fluconazole(8->64 μg/ml ). E. holmii, E. curvatum and
an unknown Exserohilum species (CBS 128064) had MICs
of itraconazole of > 16 μg/ml and clustered together in the
AFLP dendrogram. Conclusion: Amphotericin B,
posaconazole and itraconazole had good in vitro activities
against most Exserohilum species. Although variable azole
MICs were observed depending on the species,
voriconazole, the current drug of choice for therapy of
Exserohilum rostratum meningitis showed acceptable in
vitro activity.
Study supported by Astellas Pharma and Merck, Sharpe
and Dohme.

Abstract Number: NULL

Conference Year: 2013

Link to conference website: NULL

New link: NULL

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