Fungal pesticide use – does it have implications for human health?

Ref ID: 19469

Author:

L. N. Jørgensen

Author address:

Aarhus University, Denmark

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

From nature Aspergillus fumigatus is known as a saprophyte wide-
spread in nature. It is typically found in soil and decaying organic
matter, such as compost heaps, where it plays an essential role in
recycling. A. fumigatus is also known as the most important species
in human Aspergillus infection. Azole drugs are recommended for
therapy. In agriculture and industry azole antifungals are similarly
recommended for control of a broad range of plant pathogens or as
part of material preservation. Evidence indicates that azole resistance
in A. fumigatus from clinical samples is emerging in several European
countries and that the development of resistance may in part be
environmentally driven. Selection of resistance during long term
azole therapy in the clinical setting, and primary acquisition of resis-
tant isolates is well known to take place. A second way of selection
for resistance has been proposed to take place from the environment
due to the use of azoles fungicides in agriculture and from anti-fun-
gals applied for material preservation. Three specific resistance geno-
types have been found in azole na€ıve patients. Two of these have
also been found in the environment and are characterized by a tan-
dem repeat in the promoter region of the target gene coupled with
point mutation(s) in CYP51A. The latter mutations have not been
found in any of the A. fumigatus isolates that have become resistant
through patient therapy, indicating that other sources could select
for resistance.
Fungal plant pathogens cause diseases in many agricultural and
horticultural crops compromising yield and quality. Yield losses in
the range of 10-30% are not uncommon. Effective fungicides have
been available for more than 30 years and fungicides are today com-
monly used for control of plant pathogens in many crops. Azole fun-
gicides constitute the most widely used class of fungicides for control
of fungal plant pathogens in Europe. Individual azoles are recom-
mended 1-2 times per season using typically 100 to 500 g.active
ingredients. Prothioconazole, epoxiconazole, metconazole, propiconaz-
ole and tebuconazole are among the most potent and commonly used
azoles in agriculture. In comparison with other groups of fungicides
the field performances of azoles have been stable suggesting moderate
risk for development of resistance in fungal plant pathogens. Even
though other groups of chemical e.g. strobilurins are available, prob-
lems related to resistance are so significant that azoles are preferred
applied alone or in combinations with several agents in order to limit
selection of resistance. Azole resistance has appeared in several plant
pathogenic fungi and particularly the plant pathogen Mycosphaerella
graminicola has been studied. Four azole resistance mechanisms have
been found, most of which are identical to those described for A. fumigatus
1) point mutations in the CYP51, 2) upregulation of target
gene production, 3) efflux pumps, and 4) altered sterol biosynthesis.
The European population of M. graminicola is evolving into many
molecular types, which have variable sensitivity to specific azoles,
depending on CYP51 mutations, efflux and overexpression. The
changes have major impact on the field performances and are seen
as a major challenge to handle for the farming community.

Abstract Number: w17.3

Conference Year: 2013

Link to conference website: NULL

New link: NULL

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