Prevalence, antifungal susceptibility and virulence determinants of oral yeast species of immunodeficient patients from northeastern Brazil

Oral candidiasis has a common occurrence in immunocompromised patients. However, other emergent infections have become increasingly common. The aim of this study was investigate the yeast diversity colonizing the mucosa of immunocompromised patients in northeastern Brazil, evaluate the production of virulence determinants and verify the susceptibility of the isolates to some antifungal. Yeasts were identified by phenotypic and genotypic methods. In addition, we tested virulence determinants phospholipase and protease and evaluated in vitro the Minimum Inhibitory Concentration (MIC) of antifungals amphotericin B and fluconazole against these isolates. Samples from 60 immunodeficient patients were collected from subgingival sites and seeded on CHROMagar for presumptive confirmation of Candida spp. followed by PCR and sequencing. Approximately 63% of patients were colonized by yeasts, with C. albicans as the predominant species, while non-Candida albicans (NCAC) species accounted for 49% of isolates, with C. dubliniensis and C. parapsilosis being the commonest, but C. intermedia, Bullera penniseticola and Naganishia liquefaciens also were found. The virulence determinants proteinase and/or phospholipase also were produced by Candida spp. and some uncommon opportunistic isolates as Kodamaea ohmeri, N. liquefaciens and Saitozyma podzolica. Furthermore, most of Candida spp. strains and some uncommon opportunistic species showed high values of minimal inhibitory concentration (MIC). Results obtained indicate that C. albicans continues to be the predominant species in oral cavity of immunodeficient patients and along with other unusual species may present high resistance to the tested antifungals.