Fluconazole susceptibility and genotypic heterogeneity of oral Candida albicans colonies from the patients with cancer receiving chemotherapy in China / 国际口腔科学杂志·英文版

<p><b>AIM</b>To identify heterogeneity of Candida albicans (C. albicans) isolated from the population with cancer in China by using identification medium, subculture molecular typing, and antifungal susceptibility test.</p><p><b>METHODOLOGY</b>Oral cheek mucosal specimens from 52 cancer patients receiving chemotherapy were cultured on CHROMagar Candida plates for Candida identification. All the C. albicans colonies on the plates were subcultured and reconfirmed by API20C, then submitted to the antifungal drug susceptibility test with fluconazole and molecular typing using randomly amplified polymorphic DNA-PCR (RAPD) with primers RSD6 and RSD12.</p><p><b>RESULTS</b>54% (28/52) patients were oral yeast carriage in which C. albicans predominated. More than 7 C. albicans colonies were isolated from each of 12 patients (Group A), while less than 5 colonies were isolated from each of 16 patients (Group B). RSD6 and RSD12 were successful in eliciting 17 (A1-A17) and 2 (B1-B2) genotypes, respectively from among the 205 isolates. The two primers were combined to generate 21 genotypes. The C. albicans isolates obtained from the same patient and episode showed a diversity for fluconazole revealed by MIC50 and MIC90.</p><p><b>CONCLUSION</b>The heterogeneity of the C. albicans colonies isolated from the same patients can be detected. C. albicans with varied fluconazole susceptibility and genotypic characteristics may coexist in the same oral Candida population.</p>

Roles of drug efflux pump genes in the mechanism of Saccharomyces albicans biofilm drug tolerance / 华西口腔医学杂志

<p><b>OBJECTIVE</b>Saccharomyces albicons is the main opportunistic pathogen which is also the common member of oral microflora, and the biofilms they formed have spontaneous drug tolerance compared with planktonic ones. Saccharomyces biofilm population can produce subpopulation of cells which can tolerant high concentration of antifungal drugs. They are called persisters. Many researches indicated that drug efflux gene such as CDR or MDR gene plays the very important roles in yeast drug resistance. The objective of this study is to illuminate the mechanism of Saccharomyces albicons biofilm drug tolerance related with drug efflux gene, especially to the persisters formation.</p><p><b>METHODS</b>Test the minimal inhibitory concentration (MIC) and SMIC80 (sessile minimal inhibitory concentration 80%) of 24 h biofim of totally 7 defective strains of drug efflux pump gene with Amphotercin B. And treat the 24 h biofilm by fluconazole, micronazole, clotrimazole combined with CDR1 inhibitor Enniatin B respectively and antifungal drugs alone as control, then scrapped the biofilm, cultured on the YPD agar. By CFU counting, the numbers of biofilm persisters were determined.</p><p><b>RESULTS</b>All the defective strains have the similar MIC and SMIC80 for 24 h biofilm with wide type strains. CDR1 inhibitor Enniatin B can help antifungal drugs especially micronazole and clotrimazole to eliminate the biofilm persisters.</p><p><b>CONCLUSION</b>Saccharomyces albicans drug efflux gene may minor associated with 24 h biofilm drug tolerance. Drug efflux gene CDR1 may play an role in persisiters related biofilm drug tolerance.</p>