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Document 1058
DOCN M9651058
TI Mechanisms of resistance to azole antifungal agents in Candida albicans
isolates from AIDS patients involve specific multidrug transporters.
DT 9505
AU Sanglard D; Kuchler K; Ischer F; Pagani JL; Monod M; Bille J; Institut
de Microbiologie, Centre Hospitalier Universitaire; Vaudois, Lausanne,
Switzerland.
SO Antimicrob Agents Chemother. 1995 Nov;39(11):2378-86. Unique Identifier
: AIDSLINE GENBANK/X53823
AB Azole antifungal agents, and especially fluconazole, have been used
widely to treat oropharyngeal candidiasis in patients with AIDS. An
increasing number of cases of clinical resistance against fluconazole,
often correlating with in vitro resistance, have been reported. To
investigate the mechanisms of resistance toward azole antifungal agents
at the molecular level in clinical C. albicans isolates, we focused on
resistance mechanisms related to the cellular target of azoles, i.e.,
cytochrome P450(14DM) (14DM) and those regulating the transport or
accumulation of fluconazole. The analysis of sequential isogenic C.
albicans isolates with increasing levels of resistance to fluconazole
from five AIDS patients showed that overexpression of the gene encoding
14DM either by gene amplification or by gene deregulation was not the
major cause of resistance among these clinical isolates. We found,
however, that fluconazole-resistant C. albicans isolates failed to
accumulate 3H-labelled fluconazole. This phenomenon was reversed in
resistant cells by inhibiting the cellular energy supply with azide,
suggesting that resistance could be mediated by energy-requiring efflux
pumps such as those described as ATP-binding cassette (ABC) multidrug
transporters. In fact, some but not all fluconazole-resistant clinical
C. albicans isolates exhibited up to a 10-fold relative increase in mRNA
levels for a recently cloned ABC transporter gene called CDR1. In an
azole-resistant C. albicans isolate not overexpressing CDR1, the gene
for another efflux pump named BENr was massively overexpressed. This
gene was cloned from C. albicans for conferring benomyl resistance in
Saccharomyces cerevisiae. Therefore, at least the overexpression or the
deregulation of these two genes potentially mediates resistance to
azoles in C. albicans clinical isolates from AIDS patients with
oropharyngeal candidiasis. Involvement of ABC transporters in azole
resistance was further evidenced with S. cerevisiae mutants lacking
specific multidrug transporters which were rendered hypersusceptible to
azole derivatives including fluconazole, itraconazole, and ketoconazole.
DE Antifungal Agents/METABOLISM/*PHARMACOLOGY
Azoles/METABOLISM/*PHARMACOLOGY ABC Transporters/GENETICS/METABOLISM
AIDS-Related Opportunistic Infections/*MICROBIOLOGY Base Sequence
Blotting, Northern Candida albicans/*DRUG EFFECTS/GENETICS/METABOLISM
Candidiasis, Oral/*MICROBIOLOGY Drug Resistance, Microbial/GENETICS
Drug Resistance, Multiple/GENETICS DNA, Fungal/METABOLISM
Fluconazole/METABOLISM/PHARMACOLOGY Fungal Proteins/GENETICS Genes,
Fungal Human Microbial Sensitivity Tests Molecular Sequence Data
Nucleic Acid Hybridization P-Glycoprotein/GENETICS/*METABOLISM
Plasmids Polymerase Chain Reaction RNA, Fungal/METABOLISM
Saccharomyces cerevisiae/GENETICS/METABOLISM Support, Non-U.S. Gov't
JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).