Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait.
BMC Infect Dis. 2012 Sep 25;12:230. doi: 10.1186/1471-2334-12-230.
Candida albicans is the most pathogenic Candida species but shares many phenotypic features with Candida dubliniensis and may, therefore, be misidentified in clinical microbiology laboratories. Candidemia cases due to C. dubliniensis are increasingly being reported in recent years. Accurate identification is warranted since mortality rates are highest for C. albicans infections, however, C. dubliniensis has the propensity to develop resistance against azoles more easily. We developed a duplex PCR assay for rapid detection and differentiation of C. albicans from C. dubliniensis for resource-poor settings equipped with basic PCR technology and compared its performance with three phenotypic methods.
Duplex PCR was performed on 122 germ tube positive and 12 germ tube negative isolates of Candida species previously identified by assimilation profiles on Vitek 2 ID-YST system. Typical morphologic characteristics on simplified sunflower seed agar (SSA), and reaction with a commercial (Bichro-Dubli) latex agglutination test were also performed. The assay was further applied on 239 clinical yeast and yeast-like fungi and results were confirmed by DNA sequencing of internal transcribed spacer (ITS) region of rDNA.
The results of duplex PCR assay for 122 germ tube positive and 12 germ tube negative isolates of Candida species were comparable to their identification by Vitek 2 ID-YST system, colony characteristics on SSA and latex agglutination test. Application of duplex PCR also correctly identified all 148 C. albicans and 50 C. dubliniensis strains among 239 yeast-like fungi.
The data show that both, duplex PCR and Bichro-Dubli are reliable tests for rapid (within few hours) identification of clinical yeast isolates as C. dubliniensis or C. albicans. However, duplex PCR may be applied directly on clinical yeast isolates for their identification as C. dubliniensis or C. albicans as it does not require prior testing for germ tube formation or latex Candida agglutination.
白色念珠菌是最具致病性的念珠菌物种，但与杜布勒念珠菌有许多表型特征，因此在临床微生物学实验室可能会被错误识别。近年来，由于杜布勒念珠菌引起的念珠菌血症病例越来越多。由于白色念珠菌感染的死亡率最高，因此需要准确识别。然而，杜布勒念珠菌更容易对唑类药物产生耐药性。我们开发了一种用于快速检测和区分资源匮乏环境中白色念珠菌和杜布勒念珠菌的双重 PCR 检测方法，并将其性能与三种表型方法进行了比较。
对 122 例经芽管试验阳性和 12 例芽管试验阴性的念珠菌种进行双重 PCR 检测，这些菌株先前通过 Vitek 2 ID-YST 系统的同化谱进行了鉴定。还进行了简化向日葵籽琼脂（SSA）上的典型形态特征和商业（Bichro-Dubli）乳胶凝集试验。该检测方法还应用于 239 例临床酵母和酵母样真菌，结果通过 rDNA 内转录间隔区（ITS）的 DNA 测序进行确认。
122 例芽管试验阳性和 12 例芽管试验阴性的念珠菌种的双重 PCR 检测结果与 Vitek 2 ID-YST 系统、SSA 上的菌落特征和乳胶凝集试验的鉴定结果相当。239 例酵母样真菌中，148 株白色念珠菌和 50 株杜布勒念珠菌的双重 PCR 检测结果均正确。
数据表明，双重 PCR 和 Bichro-Dubli 均是快速（数小时内）鉴定临床酵母分离株为杜布勒念珠菌或白色念珠菌的可靠方法。然而，双重 PCR 可直接应用于临床酵母分离株，以鉴定其为杜布勒念珠菌或白色念珠菌，因为它不需要事先进行芽管形成或乳胶念珠菌凝集试验。
