Epidemiology of antifungal drug resistance

Ref ID: 19348

Author:

A. Gomez Lopez and S. Arikan-Akdagli

Author address:

NULL

Full conference title:

6th Trends in Medical Mycology 2013

Date: 11 October 2014

Abstract:

Antifungal drug resistance remains as one of the challenges in anti-
fungal therapy. The significance of antifungal resistance relies mainly
on increase in knowledge and awareness of primary resistance and
emergence of secondary resistance. The concept of resistance harbors
unique features for each genus-drug combination in terms of epide-
miology. In this meet-the-expert session, epidemiology of azole and
echinocandin resistance in Candida and azole resistance in Aspergillus
will be outlined and discussed.
Regarding Candida diseases, it is important to note that the
increased use of antifungals, specially azoles as prophylaxis and
empirical treatment, and of echinocandins as first-line agents for pro-
ven infection occurring over the last decade has strongly contributed
to the change in susceptibility patterns of Candida species, and in
consequence to the epidemiology of this disease.
Candida albicans is still the leading cause of candidiasis worldwide,
but important geographical differences in species distribution and
patterns of in vitro susceptibilities to antifungal agents have been
reported. Recent global sentinel surveillance programs revealed an
increasing trend in resistance to azoles, particularly fluconazole,
among several species (C. glabrata) and detected a shift in species dis-
tribution from a preponderance of C. albicans to less azole-susceptible
Candida spp. Worth of mentioning is the situation of echinocandins, a
relatively new class of antifungal agents, which appear as a preferred
therapy for invasive candidiasis due to their potency and broad spec-
trum. Resistance is an emerging threat to their use, especially in Candida
glabrata. Moreover, the use of the updated species-specific clinical
breakpoints has demonstrated slight changes in resistant rates com-
pared to previous studies.
It has also been noted that previous exposure to azoles or candins
appears to affect the species distribution for subsequent candidaemia
cases, with a higher proportion of C. glabrata after fluconazole treat-
ment and of C. parapsilosis after echinocandin exposure. It should
also be taken into consideration that the development of multidrug
resistance (fluconazole and echinocandins) that was recently detected
in C. glabrata poses a serious threat to therapy options.
Azole resistance in Aspergillus, on the other hand, drew attention in
1997 following the report on high itraconazole MICs among Aspergillus
fumigatus strains. So far, international surveillance studies, ARTE-
MIS program and SCARE network and national studies have been
carried out to determine the azole resistance in Aspergillus. While
most of the currently available data are for the resistance in strains of
Aspergillus fumigatus complex, there are more recently published (but
yet limited) data also for other Aspergillus species complexes.
Azole-resistant strains of A. fumigatus have so far been shown to
exist among those from Austria, Australia, Belgium, Brazil, Canada,
China, Czech Republic, Denmark, France, Germany, India, Italy,
Japan, the Netherlands, Portugal, Spain, Sweden, Switzerland, the
United Kingdom, and the United States at varying frequencies. Possi-
ble acquisition of azole resistant Aspergillus strains appears to be
either via selection of resistance in vivo in the individual patient or
acquisition of resistant strains from the environment. While azole
therapy remains as the major risk factor for the former, agricultural
use of azole compounds has been demonstrated to be a source for
the latter. The existence of azole-resistant Aspergillus fumigatus com-
plex strains in the environment has already been shown in the
Netherlands, Denmark, and Spain. Furthermore, studies on clinical
strains of non-fumigatus Aspergillus suggest that azole resistance is
observed among strains of Aspergillus niger and Aspergillus ustus
complexes.
Conclusively, continued surveillance of antifungal resistance needs
to be maintained in each center to determine the resistance rates
and any possible trend of increase in the isolation frequency of resis-
tant clinical strains. Based on the demonstration of significance of
agricultural azole use in development of azole resistant Aspergillus
strains, exploring the environmental sources also remains of special
interest.

Abstract Number: m-07

Conference Year: 2013

Link to conference website: NULL

New link: NULL

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