There are increasing repeated reports of amphotericin

There are increasing repeated reports of amphotericin B-resistance in pathogenic fungi including Candida spp. [35], [36]. Nolte et al. characterized some fluconazole and amphotericin B-resistant Candida albicans isolates from leukemia patients [37]. Fan-Havard et al. (1991) have shown multi-antifungal resistant Candida nm to lb with a full resistance to some antifungals such as amphotericin B [38]. In another study, resistance rate of amphotericin B and fluconazole were reported 32 and 66% for all Candida species respectively [39]. Our results showed that (Table 3) 13 isolates of C. albicans, 8 isolates of C. tropicalis, 1 isolate of C. glabrata and the only isolate of C. dubliniensis were resistant to all of 4 antifungal drugs. As shown in Table 3, C. albicans and Candida non-albicans isolates presented the most sensitivity to fluconazole (37.5% and 57.15%, respectively). The highest drug resistance rate belonged to amphotericin B in C. albicans and Candida non-albicans isolates. Taken together, as there is little information about OPC in Iranian head and neck cancer patients treated by RT, our study was carried out for the first time to evaluate virulence of OPC in these patients and revealed common species and their pathogenic characterization and correlation with sex and age of these patients. We showed that the most causative agent of OPC infection was C. albicans and the majority of the albicans and non-albicans isolates had a high capacity for biofilm formation. Although they were highly resistant to antifungal agents, fluconazole was the most effective antifungal agent against C. albicans and Candida non-albicans isolates despite the global increase in azole resistance of Candida isolates. Identification in species level and antifungal susceptibility pattern are helpful to use suitable antifungal drugs and prevent antifungal resistance.
Disclosure of interest
Acknowledgments This work was financially supported by the Pasteur Institute of Iran (Project No. 870). The authors wish to thank Dr. Fariborz Bahrami and Fereydoon Naghibi from Pasteur Institute of Iran for English and France language editing.
Introduction Over the last decades, there has been a significant increase in the incidence of fungal infections in humans, mainly affecting immunocompromised patients [1,2]. Among the fungi of clinical importance, pathogenic yeasts of the genus Candida and Cryptococcus are the most relevant [3], since candidemia is the third or fourth most common cause of healthcare-associated bloodstream infections in US hospitals [4]. Also in Brazil, mortality rates of candidemia can exceed more than half of the clinical cases [5,6]. The main pathogenic species of the genus Candida are C. albicans, C. parapsilosis, C. tropicalis, C. glabrata, C. krusei, C. guilliermondii and C. lusitaniae. Among those, C. albicans is the most frequently isolated agent of candidiasis, but non-albicans species of Candida have also increased their prevalence and gained clinical significance worldwide in the last years [7,8]. Cryptococcosis is an infectious disease with worldwide distribution and a wide array of clinical presentations caused by pathogenic encapsulated yeasts in the genus Cryptococcus, mainly C. neoformans and C. gattii [9]. Cryptococcal meningitis is one of the most important HIV related opportunistic infections and it is associated with significant mortality, approximately 181,100 deaths per year [10]. Paracoccidioidomycosis (PCM) is a disease mostly limited to Latin America and is caused by one of the two known species of the genus Paracoccidioides, P. brasiliensis and P. lutzii. PCM is the highest cause of mortality among systemic mycoses in Brazil, causing 1.65 deaths per 106 inhabitants [[11], [12], [13]]. The treatment of fungal infections is very limited, when compared to bacterial infections, with only a limited number of available drugs. This is attributable to the nature of the fungal's cell that, as eukaryotic organisms, contain few drug targets not shared with human hosts [14]. Although much progress has been achieved in the development of therapeutic alternatives for treatment of these infections, the search for new antifungal compounds is still mandatory because of the serious side effects of available drugs and emergence of resistance [15].