Performance comparison of phenotypic and molecular methods for detection and differentiation of <it>Candida albicans</it> and <it>Candida dubliniensis</it>

• Main Authors: Ahmad Suhail, Khan Ziauddin, Asadzadeh Mohammad, Theyyathel Ajmal, Chandy Rachel
• Format: Article
• Language: English
• Published: BMC 2012-09-01
• Series: BMC Infectious Diseases
• Subjects: <it>Candida albicans</it>; <it>Candida dubliniensis</it>; Detection; Differentiation; Duplex PCR
• Online Access: http://www.biomedcentral.com/1471-2334/12/230

<p>Abstract</p> <p>Background</p> <p><it>Candida albicans</it> is the most pathogenic <it>Candida</it> species but shares many phenotypic features with <it>Candida dubliniensis</it> and may, therefore, be misidentified in clinical microbiology laboratories. Candidemia cases due to <it>C. dubliniensis</it> are increasingly being reported in recent years. Accurate identification is warranted since mortality rates are highest for <it>C. albicans</it> infections, however, <it>C. dubliniensis</it> has the propensity to develop resistance against azoles more easily. We developed a duplex PCR assay for rapid detection and differentiation of <it>C. albicans</it> from <it>C. dubliniensis</it> for resource-poor settings equipped with basic PCR technology and compared its performance with three phenotypic methods.</p> <p>Methods</p> <p>Duplex PCR was performed on 122 germ tube positive and 12 germ tube negative isolates of <it>Candida</it> 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.</p> <p>Results</p> <p>The results of duplex PCR assay for 122 germ tube positive and 12 germ tube negative isolates of <it>Candida</it> 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 <it>C. albicans</it> and 50 <it>C. dubliniensis</it> strains among 239 yeast-like fungi.</p> <p>Conclusions</p> <p>The data show that both, duplex PCR and Bichro-Dubli are reliable tests for rapid (within few hours) identification of clinical yeast isolates as <it>C. dubliniensis</it> or <it>C. albicans</it>. However, duplex PCR may be applied directly on clinical yeast isolates for their identification as <it>C. dubliniensis</it> or <it>C. albicans</it> as it does not require prior testing for germ tube formation or latex Candida agglutination.</p>