Emergence of multi triazole-resistant Aspergillus fumigatus carrying the TR46/Y121F/T289A mutations in cyp51A gene from Indian environment

Ref ID: 19381

Author:

A. Chowdhary,1 C. Sharma,2 S. Kathuria,2 F. Hagen3 and J. F.
Meis3

Author address:

1Vallabhbhai Patel Chest Institute, Delhi, India; 2Department of
Medical Mycology, V.P.Chest Institute, University of Delhi, Delhi,
India and 3Department of Medical Microbiology and Infectious,
Canisius-Wilhelmina Hospital, Nijmegen, the Netherlan

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Objective Aspergillosis due to multi-triazole resistant (MTR) Aspergil-
lus fumigatus strains occur both in azole treated as well as in azole
na€ıve patients. The commonly reported mechanism of MTR, TR34/
L98H has increasingly been reported from Dutch patients and their
environment as well as in other European countries and more
recently from China, India and Iran. Molecular studies from Europe
and India suggest that clinical azole resistant isolates originated from
environmental or fungicide driven route of resistance development.
Recently, a new resistance mechanism TR46/Y121F/T289A in
cyp51A gene responsible for voriconazole resistance in A. fumigatus
has been reported in clinical and environmental isolates from
the Netherlands. This study investigated occurrence of TR46/Y121F/
T289A in A. fumigatus strains from the environment in India. We
also studied cross resistance of environmental TR46/Y121F/T289A
A. fumigatus isolates to commonly used azole fungicides in India.
Methods A total of 102 environmental soil samples from the agri-
cultural fields of Yamuna bank, Delhi (n = 50) and Varanasi, Uttar
Pradesh (n = 52), were investigated during October 2012 to April
2013. The samples were inoculated on Sabouraud dextrose agar
(SDA) plates and A. fumigatus colonies were subcultured on SDA
plates supplemented with 4 lg/mL itraconazole and 1 lg/mL vorico-
nazole. Identification of ITC+ and VRC+ A. fumigatus strains was con-
firmed by ITS, b- 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 8 azole fungicides (bromuconazole, cyproconazole, difenoconazole
epoxiconazole, metconazole, penconazole, tebuconazole and triadime-
fon) most commonly used in India were investigated using CLSI
M38-A2 broth microdilution.
Results Of 102 soil samples, 48(47%) showed A. fumigatus. Of
these, 126 colonies of A. fumigatus were isolated on SDA. A total
of 10 isolates grew on 1 lg/mL voriconazole (6 from Varanasi,
U.P) and 4 lg/mL itraconazole (4 from Delhi) SDA. Six VRC+ A. fu-
migatus originated from 2 soil samples of Varanasi. Of these, 5
(83.3%) were from a potato field and 1 (16.6%) was from Trigonella
foenum-graecum (common name Fenugreek) field. Four ITC+ A. fu-
migatus isolates originated from Yamuna bank, Delhi. Overall, 5.8%
of the samples harbored voriconazole and 6.8% had itraconazole
resistant A. fumigatus. The geometric mean MICs of 6 VRC+ A. fu-
migatus isolates showed reduced susceptibility of voriconazole
(10.07 lg/mL) and isavuconazole (8 lg/mL). These isolates exhib-
ited low itraconazole MICs (1.78 lg/mL) but showed cross- resis-
tance to all the fungicides tested. All six VRC+ A. fumigatus isolates
exhibited the TR46/Y121F/T289A mutation and had the same
genotype as Dutch isolates. In addition 4 ITC+ A. fumigatus were of
genotype TR34/L98H.
Conclusion This is the first environmental survey outside Europe
revealing emergence of the new resistance mechanism TR46/
Y121F/T289A in A. fumigatus. Microsatellite typing of these environ-
mental isolates showed them to be very similar to Dutch clinical iso-
lates. The widespread application of triazole fungicides and its
persistence in the environment could have contributed to spread of
azole resistant A. fumigatus.

Abstract Number: p031

Conference Year: 2013

Link to conference website: NULL

New link: NULL

Conference abstracts, posters & presentations

Showing 10 posts of 17325 posts found.

  • Title

    Author

    Year

    Number

    Poster