[Identification of Candida dubliniensis strains using heat tolerance tests, morphological characteristics and molecular methods].
Described in 1995, Candida dubliniensis is a novel Candida species closely related to Candida albicans due primarily to its ability to produce germ tube and chlamydospores. Given these phenotypic similarities between the two species, C. dubliniensis cannot be readily distinguished from Candida albicans by routine laboratory work-up. We explored the frequency of isolation of C. dubliniensis among 213 strains previously defined as C. albicans based on their ability to produce germ tube. The test isolates were initially examined for their morphological features on cornmeal tween 80 agar, inability to grow at 45 degrees C, and the biochemical assimilation profile (ID 32C system, bioMerieux, France). Among all, 2 (0.9%) of the isolates were identified as C. dubliniensis based on the production of numerous chlamydospores in chains on cornmeal tween 80 agar and the lack of growth at 45 degrees C. The assimilation profile of these isolates was found to be in accordance with this identification. In an effort to confirm the identification, polymerase chain reaction (PCR) studies were carried out by using the C. dubliniensis specific primer set, DUBF and DUBR. Both of the isolates yielded C. dubliniensis-specific 288 base pair amplification products, confirming the previous identification obtained with the initial screening tests. The isolates were found to be susceptible to fluconazole and itraconazole, and generated amphotericin B minimal inhibitory concentrations of 0.5-1 microgram/ml by NCCLS M27-A2 microdilution method. These data suggest that the isolation rate of C. dubliniensis among our clinical isolates is low. The morphological features on cornmeal tween 80 agar and the lack of ability to grow at 45 degrees C appear as reliable, cheap, and practical screening tests in initial identification of C. dubliniensis among germ tube-producing Candida strains.
Arikan
Sevtap
S
Hacettepe Universitesi Tip Fakültesi, Mikrobiyoloji ve Klinik Mikrobiyoloji Anabilim Dali, Ankara.
Darka
Ozge
O
Hasçelik
Gülşen
G
Günalp
Ayfer
A
D000935:Antifungal Agents / Q000494:pharmacology; D002175:Candida / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D003470:Culture Media; D006358:Hot Temperature; D006801:Humans; D016133:Polymerase Chain Reaction; D011136:Polysorbates; D013172:Spores, Fungal; D013501:Surface-Active Agents; D003313:Zea mays
D000935:Antifungal Agents; D003470:Culture Media; D011136:Polysorbates; D013501:Surface-Active Agents