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    • The studies have described that

    2022-11-09

    The studies have described that Candida non-albicans are considered as remarkable pathogenic agents of OPC, and among them, C. tropicalis and C. glabrata are known as major strains that may replace C. albicans as the greatest causing agent of this infection [20], [21]. It has been shown that Candida infections among the cancer patients are commonly caused by C. albicans, followed by C. tropicalis and C. glabrata in terms of importance [22]. We showed that C. albicans (53.3%) was the most species responsible for OPC and C. tropicalis (21.66%) and C. glabrata (15%) were the second and third species which are consistent with data in other studies. It has been demonstrated that factors including the abuse of broad-spectrum 974 along with the high consumption of immunosuppressive agents are accelerating the increase of C. tropicalis and C. glabrata infections [23], [24]. The studies have shown that Pichia spp. was capable of causing infection alone and without other Candida species [25]. In this study, we isolated two Pichia species with no other Candida species from two patients. The details of Pichia species identification and antifungal susceptibility were mentioned in Table 3. Biofilm formation is one of the important virulence factors of Candida species. Previous studies have shown that the strains that are able to produce more biofilm are more virulent and can cause severe Candida infections depending on the patient ꞌs immunosuppression level [26]. Our data showed that all of the 58 Candida isolates investigated here had the ability to form biofilm. Among them, 57 isolates were high producers and even 48 isolates of them revealed biofilm formation ability over standard strain C. albicans ATCC10231. Only one isolate was in low producer scoring. It has demonstrated that biofilm formation ability of C. tropicalis species is higher than other species [13]. In our study, all of C. tropicalis isolates showed high biofilm producing (4+) specification. The studies showed that there is strong relationship among pathogenicity and phospholipase and proteinase activity of Candida spp. [15]. Our results showed that proteinase activity were detected in all of the Candida isolates and the most of Candida isolates were capable of phospholipase production. The studies on the phospholipase production in Candida spp. have shown that phospholipase activity is variable in C. tropicalis species. Samara et al. and Yu et al. demonstrated that there was no phospholipase activity in C. tropicalis strains under their studies [27], [28]. However, other studies reported phospholipase activity in C. tropicalis isolates. Jiang et al. showed that just 31 isolates of 52 clinical C. tropicalis had phospholipase activity with a low production of the enzyme [29]. In another study, on 29 strains, low or no phospholipase activity in clinical C. tropicalis isolates were revealed [30]. We showed that 2 isolates (15.33%) out of 13 isolates had no activity, 3 (23.07%) isolates showed low activity and 8 (61.55) isolates had high phospholipase activity (Table 4) which the rate of the activity of this enzyme was higher than previous reports. The literature reveals that there is no strong evidence to declare that one specific antifungal agent is superior to other drugs for treatment of OPC [17]. The antifungal resistant species of Candida isolates have been on the rise in recent years. Despite many studies which have revealed that fluconazole resistance is increasing among C. albicans and non-albicans isolates that colonize or cause OPC infection [31], [32], [33], fluconazole, is the most common antifungal that is broadly used in OPC cases. This azole-based drug is extremely effective and is well tolerated by the patients [34]. We showed that (Table 3) the sensitivity of Candida non-albicans isolates to fluconazole was 57.13%. Meanwhile, the sensitivity of C. albicans isolates to fluconazole appeared 37.5%, which was the most among other antifungals. Furthermore, the resistance of Candida non-albicans isolates to itraconazole, ketoconazole, amphotericin B and fluconazole were 85.71%, 89.28%, 69.28% and 42.85%, respectively.