Implication of efflux pumps and ERG11 genes in resistance of clinical Trichosporon asahii isolates to fluconazole

Abstract

Introduction. Trichosporon asahii has been recognized as an opportunistic agent having a limited sensitivity to antifungal treatment. Hypothesis/Gap Statement. Molecular mechanisms of azole resistance have been rarely reported for Trichosproron asahii. Similar to other fungi, we hypothesized that both ERG11 gene mutation and efflux pumps genes hyper-expression were implicated. Aim. The current work aimed to study the sensitivity of clinical T. asahii isolates to different antifungal agents and to explore their resistance mechanisms by molecular methods including real-time PCR and gene sequencing. Methods. The sensitivity of T. asahii isolates to fluconazole, amphotericin B and voriconazole was estimated by the Etest method. Real-time PCR was used to measure the relative expression of Pdr11, Mdr and ERG11 genes via the ACT1 housekeeping gene. Three pairs of primers were also chosen to sequence the ERG11 gene. This exploration was followed by statistical study including the receiver operating characteristic (ROC) curve analysis to identify a relationship between gene mean expression and the sensitivity of isolates. Results. In 31 clinical isolates, the resistance frequencies were 87, 16.1 and 3.2 %, respectively, for amphotericin B, fluconazole and voriconazole. Quantitative real-time PCR demonstrated that only Mdr over-expression was significantly associated with FCZ resistance confirmed by univariate statistical study and the ROC curve analysis (P <0.05). The ERG11 sequencing revealed two mutations H380G and S381A in TN325U11 (MIC FCZ=8 µg ml−1) and H437R in TN114U09 (MIC FCZ=256 µg ml−1) in highly conserved regions (close to the haem-binding domain) but their involvement in the resistance mechanism has not yet been assigned. Conclusion. T. asahii FCZ resistance mechanisms are proven to be much more complex and gene alteration sequence and/or expression can be involved. Only Mdr gene over-expression was significantly associated with FCZ resistance and no good correlation was observed between FCZ and VCZ MIC values and relative gene expression. ERG11 sequence alteration seems to play a major role in T. asahii FCZ resistance mechanism but their involvement needs further confirmation.

Identification and Antifungal Susceptibility Analysis of Stephanoascus ciferrii Complex Species Isolated From Patients With Chronic Suppurative Otitis Media

“… Sasani et al (2021) reported that the formation of biofilms and the overexpression of ERG11 and UPC2 genes in Candida tropicalis were related with fluconazole resistance. Abbes et al (2021) found that Mdr gene overexpression in Trichosporon asahii isolates was significantly associated with fluconazole resistance. However, there are no articles reporting why fluconazole resistance is high also in this complex.…”

Nanotechnology-Based Approaches for Voriconazole Delivery Applied to Invasive Fungal Infections

“…However, studies have shown a reduction in the susceptibility of fungi compared to the available classes [ 23 , 24 ]. The main factors related to decreased antifungal susceptibility are drug target overexpression, efflux pumps, and amino acid substitution [ 25 , 26 ]. In addition, another limitation to the use of current antifungals is the presence of adverse effects, the main ones being nephrotoxicity and hepatotoxicity [ 27 , 28 ].…”

Esporotricose: Aspectos Gerais, Epidemiologia, Identificação, Patogenia, Diagnóstico E Tratamento – Revisão De Literatura

“…Tendo em vista a gravidade das infecções sistêmicas e a crescente resistência aos antimicrobianos atualmente utilizados na clínica, é preciso uma constante atualização acerca da patogenia da doença e da interação entre o fungo e o bem como o correto diagnóstico, considerando os fatores de virulência e seus potenciais alvos farmacológicos (DUARTE-OLIVEIRA et al, 2017;ABBES et al, 2021;MEHTA et al, 2021).…”