Abstract
BackgroundThe aim of this study was to determine the biofilm formation, the extracellular enzymatic activities of 182 clinical isolates of the Candida parapsilosis complex. MethodsMolecular identification of the C. parapsilosis species complex was performed using PCR RFLP of SADH gene and PCR sequencing of ITS region. The susceptibility of ours isolates to antifungal agents and molecular mechanisms underlying azole resistance were evaluated.Results63.5% of C. parapsilosis were phospholipase positive with moderate activity for the majority of strains. None of the C. metapsilosis or C. orthopsilosis isolates was able to produce phospholipase. Higher caseinase activities were detected in C. parapsilosis (Pz = 0.5 ± 0.18) and C. orthopsilosis (Pz = 0.49 ± 0.07) than in C. metapsilosis isolates (Pz = 0.72 ± 0.1). 96.5% of C. parapsilosis strains and all isolates of C. metapsilosis and C. orthopsilosis produced gelatinase. All the strains possessed the ability to show haemolysis on blood agar. C. metapsilosis exhibited the low haemolysin production with statistical significant differences compared to C. parapsilosis and C. orthopsilosis. The biofilm forming ability of C. parapsilosis was highly strain dependent with important heterogeneity, which was less evident with both C. orthopsilosis and C. metapsilosis.Some C. parapsilosis isolates met the criterion for susceptible dose dependent to fluconazole (10.91%), itraconazole (16.36%) and voriconazole (7.27%). Moreover, 5.45% and 1.82% of C. parapsilosis isolates were respectively resistant to fluconazole and voriconazole. All strains of C. metapsilosis and C. orthopsilosis were susceptible to azoles; and isolates of all three species exhibited 100% of susceptibility to caspofungin, amphotericin B and 5-flucytosine.ConclusionsA combination of molecular mechanisms, including the overexpression of ERG11, and genes encoding efflux pumps (CDR1, MDR1, and MRR1) were involved in azole resistance in C. parapsilosis.
Highlights
The aim of this study was to determine the biofilm formation, the extracellular enzymatic activities of 182 clinical isolates of the Candida parapsilosis complex
The aim of our study was to investigate the distribution of five virulence factors namely: biofilm production, caseinase, gelatinase, phospholipase and haemolysin extracellular production among C. parapsilosis complex isolates
In our study, we evaluated the in vitro capacities of 172 C. parapsilosis isolates, 6 C. metapsilosis isolates, 4 C. orthopsilosis isolates and 32 C. albicans isolates to produce phospholipase, hemolysin and proteases
Summary
The aim of this study was to determine the biofilm formation, the extracellular enzymatic activities of 182 clinical isolates of the Candida parapsilosis complex. Many virulence factors contribute to the pathogenesis of candidiasis, allowing the fungal cells to escape and/or overcome the host defenses Among these factors proposed in the literature, adherence to host cells and/or tissues as well as to inert supports, phenotypic switching, biofilm formation and secretion of a large array of hydrolytic enzymes are included [1, 45, 47, 60]. Differences in these virulence factors among C. parapsilosis complex species have not been widely investigated. A better knowledge could have clinical relevance, as it may be useful in guiding therapeutic decisions [13]
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