Detection of Species Diversity in Oral Fungi Colonization and Anti-Fungal susceptibility among Non-Oral Habit adult patients

Abstract

Background: The fluctuating spectrum of Candida species in the oral environment and their antifungal susceptibility pattern, especially among the immunocompromised individuals, have made the identification of Candida species and the detection of their drug resistance is important for quality patient care. The aims of this study are to identify and specify oral fungal species among dental patients and to assess their susceptibility to the commonly used antifungal drugs. Oral rinses were collected randomly from 120 consecutive patients who made routine check-ups at 3 different dental clinics during the year 2021. Included patients are adults, aged 18 years or above, not receiving chemotherapy or radiotherapy, and not currently taking any antifungal drugs or antibiotics. Oral rinses were collected using standard methods from each patient. Species identification and antifungal susceptibility tests of Candida isolates were performed using a semi-automated microbial identification system: “Integral System Yeasts Plus” (ISYP). A total of 59(49.1%) cases were found to have positive growth in yeasts. Out of these cases, Candida albicans was the most predominantly isolated yeast in 39 cases (66%), followed by Candida tropicalis in 8(13.6%), Candida dubliniensis in 3(5.1%), Rhodotorula rubra in 2(3.4%), and 1 case from each of the other species. The overall resistance rates for the tested antifungals were as follows: nystatin (6.8%), amphotericin B(6.8%), flucytosine (3.4%), econazole (10.2%), ketoconazole (1.7%), clotrimazole (13.6%), miconazole (10.2%), itraconazole (8.5%), voriconazole (8.5%), and fluconazole (11.9%). Most fungal species in this study are either sensitive or intermediately sensitive to most antifungal agents, except Candida stellatoidea, which was resistant to all the tested antifungals, and Candida catenulata, which was sensitive only to ketoconazole and voriconazole. Rhodotorula rubra was resistant to 50% of the tested antifungals. The outcome of this study recognized that oral fungi species are predominated by Candida albicans with variable antifungal susceptibility; however, most are sensitive to the commonly available antifungals. The combination of identification ability and drug susceptibility testing is helpful, especially from the clinical point of view.