Oral candidiasis in patients with type II Diabetes: Comparision of a novel multiplex PCR and chromagar in species identification

Abstract

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Background: Diabetes mellitus is a global epidemic. Oral candidiasis is being frequently recognized in diabetic patients, due to elevated glucose in their oral fluids and immune dysfunction. Oral candidiasis is associated with multiple pathogens including C.albicans, C.parapsilosis, C.glabrata and C.tropicalis. The aim of this study was to evaluate a multiplex PCR as a rapid diagnostic tool for identification of above four oral Candida pathogens. Methods & Materials: A multiplex PCR was optimized to identify C.albicans, C.parapsilosis, C.glabrata and C.tropicalis in concentrated oral rinse samples of patients with diabetes, attending the Endocrinology clinic at Colombo South Teaching hospital, Sri Lanka. Common reverse primer, ITS4 and four species specific forward primers targeting ITS 1 and ITS2 regions of yeast genome (primer CA, CT, CP, and CGL respectively) were used. Oral rinse samples (n = 100) were used to compare between multiplex PCR and phenotypic identification. Results: Out of the 100 oral rinse samples, 77 were culture positive and of these 44 were colonized (> 600 CFU/ml). Multiple Candida species including C.albicans, C.parapsilosis and C.tropicalis were identified in 33 of the colonized samples. Eighty two patients were positive for Candida bymultiplex PCR and of them 47 hadmultiple Candida species. All 44 colonized specimens were also positive by multiplex PCR. C.albicans was the most predominant organism (73/82) followed by C.parapsilosis (46/82), C.tropicalis (16/82) and C.glabrata (6/82). In specimens with multiple species, the two most common organisms were C.albicans and C.parapsilosis. Out of the 61 Candida isolates that were germ tube negative, 15 isolates were identified as C.albicans by the typical green colour on CHROMagar. However two out of fifteen isolates were negative for C.albicans by multiplex PCR indicating that results of CHROMagar should be interpreted cautiously. Further C.glabrata could not be identified using phenotypic identification but was identified by multiplex PCR. Multiplex PCR yielded a sensitivity of 10 Candida cells/ml of oral rinse sample. Conclusion: Multiplex PCR is found to be rapid, highly sensitive and specific than phenotypic identification methods in discriminating multiple Candida species directly in oral rinse specimens.