Abstract:
Specific medical interventions and changes in the host of ever-expanding
immunocompromised population due to the rise of AIDS, transplantation, and cancer
therapies have led to the emergence of uncommon but medically important fungal
pathogens. Although Candida albicans and Aspergillus fumigatus remain the most frequent
pathogens of invasive fungal infections, uncommon Candida and Aspergillus species can
also cause serious infections. Other uncommon emerging fungal pathogens belong to the
group of Zygomycetes, to hyaline moulds including Fusarium, Scedoporium, Acremonium,
and Paecilomyces, to dematiaceous fungi including Alternaria, Curvularia, Bipolaris, and
Exophiala, and to other yeasts like Saccharomyces cerevisiae and Rhodotorula mucilaginosa
and Trichosporon species. Infections caused by these pathogens are often associated with
poor outcome and require highly aggressive strategies of antifungal therapy.
Decreased susceptibility to fluconazole and/or amphotericin B is observed among isolates of
uncommon Candida species such as C. kefyr, C. lusitaneae, C. guilliermondii, C. famata, C.
rugosa, C. inconspicua, and C. lambica. Newer azoles and echinocandins may exhibit
stronger activity against these isolates. The newly described species C. orthopsilosis and C.
metapsilosis, which are genetically related with C. parapsilosis, are susceptible to
amphotericin B, echinocandins and azoles; although fluconazole MICs are higher and
anidulafungin MICs are lower than those of C. parapsilosis. Some isolates of C. glabrata
cryptic species C. nivariensis and C. bracarensis may exhibit significant in vitro resistance to
itraconazole, voriconazole, fluconazole and flucytosine. Newly described Aspergillus species
belonging to A. fumigatus complex (A. udagawae, N. pseudofischeri, A. lentulus), A. ustus
complex (A. calidoustus), A. versicolor complex (A. sydowii), A. niger complex (A.
tubingensis) and A. nidulans complex (E. quadrilineata) demonstrate decreased susceptibility
to antifungal drugs including amphotericin B and the new triazoles. Zygomycetes are usually
resistant to most antifungal drugs with amphotericin B and posaconazole exhibiting the
strongest in vitro activity. In vitro testing of Fusarium spp. and Acremonium spp. has shown
decreased susceptibility to most antifungal agents. Scedoporium spp. demonstrate
resistance to currently available antifungals, with albaconazole and voriconazole being the
most active. Dematiaceous fungi are usually susceptible to amphotericin B and the new
triazoles with slightly higher MICs for voriconazole. Trichosporon spp. are mostly resistant to
flucytosine and echinocandins, susceptible to azoles with voriconazole being the most potent
compound and susceptible to amphotericin B with the exception of T. asahii.
The new advances in antifungal chemotherapy give more options to treat infections caused
by these uncommon fungal pathogens but require a good knowledge of the susceptibility
profiles.
2009
abstract No:
W04.2
Full conference title:
4th Trends in Medical Mycology
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- TIMM 4th (2012)