Voriconazole resistant Aspergillus fumigatus carrying TR46/Y121F/T289A mutation from the Indian Environment

Ref ID: 19490

Author:

C Sharma1*, F Hagen2, JF Meis2,3, A Chowdhary1

Author address:

1Department of Medical Mycology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
2Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen,
The Netherlands
3Department of Medical Micro

Full conference title:

6th Advances Against Aspergillosis 2014

Abstract:

Purpose:
The emergence of a new resistance mechanism, TR46/Y121F/T289A in the cyp51A gene responsible
for voriconazole resistance in Aspergillus fumigatus, has been recently reported in patients and
from their environment in the Netherlands. Molecular studies of well-studied pan azole resistant
A. fumigatus carrying TR34/ L98H mutation from Europe and India suggest that clinical azole
resistant isolates originated from environmental or fungicide driven route of resistance development.
The present study reports the occurrence of TR46/Y121F/T289A in A. fumigatus strains from
environmental sources in three cities of India.
Methods:
A total of 117 environmental soil samples from the agricultural fields of Yamuna bank, Delhi (n=63),
Varanasi, Uttar Pradesh (n=42) and soil from Ganga river basin and nearby forest (n=12) area
from Himachal Pradesh, were investigated during October 2012 to June 2013. The samples were
inoculated on Sabouraud dextrose agar (SDA) plates and A. fumigatus colonies were subcultured
on SDA plates supplemented with 4μg/mL itraconazole (ITC) and 1μg/mL voriconazole (VRC).
Identification of ITC+ and VRC+ A. fumigatus strains was confirmed by ITS, β -tubulin and
calmodulin gene. All the ITC+ and VRC+ A. fumigatus were subjected to a mixed-format real-time
PCR assay for detection of mutations and genotyped with microsatellite analysis. In vitro activity
for all the standard azole antifungals and the 10 azole fungicides (bromuconazole, cyproconazole,
difenoconazole epoxiconazole, hexaconazole, metconazole, penconazole, tebuconazole, triadimefon
and tricyclazole) most commonly used in India were investigated using CLSI M38-A2 broth
microdilution.
Results:
Of 117 soil samples, 47 (40%) samples (Delhi, n=27; Varanasi, n=10; Himachal Pradesh, n=10)
yielded 198 A. fumigatus strains, including 88 from Delhi, 38 from Varanasi and 72 from Himachal
Pradesh, on SDA plates. A total of sixteen isolates were resistant, of which eight each (6.8%) grew
on 1 mg/L voriconazole (6 from Varanasi and 2 from Himachal Pradesh) and 4 mg/L itraconazole
(4 each from Delhi and Varanasi). TR46/Y121F/T289A originated from potato and Trigonella
foenum-graecum (common name fenugreek) fields of Varanasi and Ganga river basin soil from
Himachal Pradesh. The geometric mean MICs of 8 VRC+ A. fumigatus isolates showed reduced
susceptibility of voriconazole (11.31μg/mL) and isavuconazole (8μg/mL). These isolates exhibited
low itraconazole MICs (1.78μg/mL) but showed cross- resistance to all the fungicides tested. All
eight VRC+ A. fumigatus isolates exhibited the TR46/Y121F/T289A mutation.
Conclusion:
This is the first environmental survey outside Europe revealing presence of the TR46/Y121F/T289A
mutation in A. fumigatus strains with reduced susceptibility to voriconazole and cross resistance
to commonly used fungicides. Genotypically the Indian environmental isolates were similar to
Dutch clinical isolates. The widespread application of triazole fungicides and its persistence in
the environment could have contributed to spread of azole resistant A. fumigatus. This resistance
mechanism in A. fumigatus strains poses a threat to patients limiting the use of voriconazole, which
is a drug of choice for invasive aspergillosis.
NOTE: THIS ABSTRACT HAS BEEN SELECTED FOR ORAL PRESENTATION.

Abstract Number: 18

Conference Year: 2014

Link to conference website: http://www.AAA2014.org

New link: NULL

Conference abstracts, posters & presentations

Showing 10 posts of 17325 posts found.

  • Title

    Author

    Year

    Number

    Poster