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Diagnostic Approaches for Aspergillus Infections

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Front. Microbiol. | doi: 10.3389/fmicb.2018.01395

Determination of the prevalence of triazole resistance in environmental Aspergillus fumigatus strains isolated in South Wales, UK

 Alexandra Tsitsopoulou1, Raquel Posso2, Lorna Vale2, Scarlett Bebb2,  Elizabeth Johnson3 and  P. Lewis White2*
  • 1Cwm Taf University Health Board, United Kingdom
  • 2Public Health Wales NHS Trust, United Kingdom
  • 3Mycology reference laboratory (Mycology RL), United Kingdom

Background/Objectives
Azole resistance in Aspergillus fumigatus associated with the TR34/L98H mutations in the cyp51A gene have been increasingly reported. Determining the environmental resistance rate has been deemed important when considering front-line therapy for invasive aspergillosis. The aim of the study was to determine prevalence of azole resistance in environmental A. fumigatus isolates across South Wales.
Methods
Over five months in 2015, 513 A. fumigatus isolates were cultured from 671 soil and 44 air samples and were screened for azole resistance using VIP agar plates containing itraconazole, voriconazole and posaconazole. Resistance was confirmed by the CLSI M38-A2 methodology. The mechanism of resistance was investigated using the PathoNostics AsperGenius Assay.
Results
Screening by VIP plate identified azole-resistance in 30 isolates most of which (28/30) harboured the TR34/L98H mutation, generating a prevalence of 6.0%. Twenty-five isolates had a MIC of ≥2mg/L with itraconazole, 23 isolates had a MIC of ≥2mg/L with voriconazole and seven isolates had a MIC ≥0.25mg/L with posaconazole. All isolates deemed resistant by VIP plates were resistant to at least one azole by reference methodology. Conclusions
There is significant environmental azole resistance (6%) in South Wales, in close proximity to patients susceptible to aspergillosis. Given this environmental reservoir, azole resistance should be routinely screened for in clinical practice and environmental monitoring continued.

Keywords: A.fumigatus, Azole resistance, TR34, L98H, environmental prevalence

Received: 16 Apr 2018; Accepted: 07 Jun 2018.

Edited by:

Juergen Prattes, Medizinische Universität Graz, Austria

Reviewed by:

Alix T. Coste, Centre Hospitalier Universitaire Vaudois (CHUV), Switzerland
Birgit Spiess, Universitätsmedizin Mannheim, Medizinische Fakultät Mannheim, Universität Heidelberg, Germany  

Copyright: © 2018 Tsitsopoulou, Posso, Vale, Bebb, Johnson and White. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. P. Lewis White, Public Health Wales NHS Trust, Cardiff, United Kingdom, lewis.white@wales.nhs.uk