Fluorescence of Candida in diagnosis of oral candidiasis

Background: Many pathogenic fungi fluoresce in hematoxylin and eosin stained sections, and Papanicolaou (PAP)-stained smears under ultraviolet illumination. In theory, this phenomenon could aid in the diagnosis of common fungal infections without the delay which is usually associated with special stains. Objective: To evaluate the role of fluorescence as a rapid screening technique for oral infections caused by Candida organisms in exfoliative smears of oral candidiasis. Materials and Methods: Two smears and one swab were collected from each of 62 clinically diagnosed cases of oral candidiasis. Smears were stained with (PAP) and periodic acid-Schiff stain (PAS). Both smears were evaluated under light microscopy (LM). Later, PAP smears were observed under fluorescent microscopy (PAP-FM). The swab was inoculated on Sabouraud's agar plate. Each technique was evaluated for sensitivity and specificity. Results: It was found that the PAS-stained smears were more reliable for detection of Candida species than other methods (sensitivity = 100%; specificity = 66.7%). The PAP-LM and PAP-FM showed less sensitivity (67.9% and 85.7%) and specificity (66.7% and 33.3%), respectively. Combined results of both light and fluorescent microscopy of PAP (LM + FM) showed increased sensitivity (89.3%) but reduced specificity (16.7%). Conclusion: PAP autofluorescence is less sensitive than PAS, still it accentuates the distinct morphological features of Candida.