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Wednesday 08 August 2007

[Evaluation of the relationship between Candida albicans 25S intron genotypes and antifungal susceptibilities]

By: Balaban N, Karahan ZC, Mumcuoğlu I, Cayirli A, Kuştimur S.

Mikrobiyol Bul 2007 Apr;41(2):245-51

Due to the increase in the number of immunosuppressive patients, an increase in the frequency of Candida albicans infections is recorded during the recent years. C. albicans strains can be grouped into three genotypes (genotypes A, B and C) by 25S intron analysis according to the presence of a transposable group-1 intron. Genotype A isolates were found to be associated with increased resistance to flucytosine. The aim of this study was to determine the genotypic distribution of C. albicans isolates and investigate the relationship between the genotypes and antifungal susceptibility patterns. Seventy clinical C. albicans isolates were included in the study. The strains were identified by API ID 32C (bioMerieux, France), and antifungal susceptibilities were determined by ATB Fungus 2 (bioMerieux, France) system. Following DNA extraction from the isolates, polymerase chain reaction (PCR) was performed as indicated in the literature. The genotypes were determined according to the size of the amplified PCR product. For the statistical analysis of the relationship between the genotypes and antifungal susceptibility patterns, Pearson's khi square and Fisher's exact tests were performed. Among the 70 strains investigated, 35 (50%) were found as genotype A, nine (12.9%) were genotype B and 26 (37.1%) were genotype C. Nystatin, miconazole and ketoconazole susceptibilities were significantly different among the genotypes, genotype B being more resistant to these agents (p values were 0.032, 0.035 and 0.035, respectively). When the susceptibility of the strains were compared according to the presence of the transposable intron, no significant difference was observed. There was also no statistically significant difference between the genotype distribution of the isolates and flucytosine, amphotericin B and econazole susceptibilities (p values were 0.357, 0.602 and 0.051, respectively). As a result, in order to clarify the resistance mechanisms of different genotypes of C. albicans isolates, more sophisticated and large-scale studies should be performed.

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