[Oropharyngeal candidiasis resistant to fluconazole in patients infected by HIV]. / Candidoses oropharyngées résistantes au fluconazole chez des malades infectés par le VIH.

PURPOSE: To study the susceptibility to fluconazole of Candida albicans strains in oral candidiasis of HIV positive patients. PATIENTS AND METHODS: Eleven HIV positive patients with confirmed oral candidiasis were included in a 4 to 10 months prospective study. In addition, 23 HIV positive patients were evaluated in a restrospective study (14 with oral candidiasis and 9 control subjects). The MICs to fluconazole of C. albicans were characterized by genotyping (electrophoretic karyotype). RESULTS: Thirty patients were evaluable. Oral candidiasis was found in 21 patients; 7/21 patients (33,3 p. 100) developed resistant C. albicans strain (MIC > 32 mg/ml) after a mean fluconazole cumulative dose of 18 g. In this study, the electrophoretic karyotype confirmed the persistence of the same C. albicans strain in each patient. In addition increased colonization by C. krusei or C. glabrata was found in 6/21 patients (28.5 p. 100). DISCUSSION: Our data demonstrate that prolonged treatment with fluconazole dose higher than 13 g induces the emergence of resistant C. albicans with persistence of the same C. albicans strain. Fluconazole has to be reserved to oral candidiasis after failure of a local treatment or to severe cases.

[Mechanisms of psoralen photoreaction]. / Mécanismes de photoréaction des psoralènes.

The molecular aspects of the mode of action of psoralens is not clearly understood since two types of reactions may occur simultaneously and independently of each other, when the psoralen-treated skin is exposed to ultraviolet A radiation. Type 1 is an oxygen-independent reaction, leading directly to photoaddition of psoralen to pyrimidine bases of DNA, and type 2 is an indirect oxygen-dependent reaction involving the generation of reactive oxygen species. Thus, the psoralens can damage the cell membranes, the cytoplasmic constituents and the cell nuclei resulting in the observed phototoxic effects. The molecular mechanisms underlying the generation of free radicals and DNA damages are described, and are related to the two classes of psoralens.