Fluconazole and amphotericin-B resistance are associated with increased catalase and superoxide dismutase activity in Candida albicans and Candida dubliniensis.
BACKGROUND
Candida dubliniensis, a new species of Candida that has been recovered from several sites in healthy people, has been associated with recurrent episodes of oral candidiasis in AIDS and HIV-positive patients. This species is closely related to C. albicans. The enzymatic activity of C. dubliniensis in response to oxidative stress is of interest for the development of drugs to combat C. dubliniensis.


METHODS
Fluconazole- and amphotericin B-resistant strains were generated as described by Fekete-Forgács et al. (2000). Superoxide dismutase (SOD) and catalase assays were performed as described by McCord and Fridovich (1969) and Aebi (1984), respectively.


RESULTS
We demonstrated that superoxide dismutase (SOD) and catalase activities were significantly higher (p<0.05) in the fluconazole- and amphotericin B-resistant strains of C. dubliniensis and C. albicans than in the sensitive strains. The catalase and SOD activities were also significantly (p<0.01) higher in the sensitive and resistant C. albicans strains than in the respective C. dubliniensis strains.


CONCLUSIONS
These data suggest that C. albicans is better protected from oxidative stress than C. dubliniensis and that fluconazole, like amphotericin B, can induce oxidative stress in Candida; oxidative stress induces an adaptive response that results in a coordinated increase in catalase and SOD activities.
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto AlegreRS.
Carlos Eduardo Blanco
CE
Linares
Curso de Farmácia, Centro de Ciências da Saúde, Universidade Regional do Alto Uruguai e das Missões, Frederico WestphalenRS.
Sandro Rogério
SR
Giacomelli
Curso de Farmácia, Centro de Ciências da Saúde, Universidade Regional do Alto Uruguai e das Missões, Frederico WestphalenRS.
Delsi
D
Altenhofen
Departamento de Microbiologia, Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Santa MariaRS.
Sydney Hartz
SH
Alves
Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa MariaRS.
Vera Maria
VM
Morsch
Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa MariaRS.
Maria Rosa Chitolina
MR
Schetinger
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000145:classification / Q000187:drug effects* / Q000201:enzymology*; D002176:Candida albicans / Q000187:drug effects / Q000201:enzymology; D002374:Catalase / Q000378:metabolism*; D025141:Drug Resistance, Fungal; D015725:Fluconazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D013482:Superoxide Dismutase / Q000378:metabolism*
D000935:Antifungal Agents; D000666:Amphotericin B; D015725:Fluconazole; D002374:Catalase; D013482:Superoxide Dismutase