Detection of ERG11 point mutations in Iranian fluconazole-resistant Candida albicans isolates

Antifungal activity of three different varieties of Capsicum annuum against clinical isolates of Candida species

OBJECTIVE

Acquired resistance to antifungal agents is rising among Candida species. Herbal extracts including Capsicum annum extracts have biological profits, which can be employed to overcome drug resistance in fungal species. The present study investigated the efficacy of different varieties of C. annum extracts against Candida species.

METHODS

Aqueous and alcoholic extracts of three different varieties of C. annum were prepared using the succulent method. Total values for compound extracts of C. annum var. cayenne, C. annum var. cayenne cultivar sabzevari, and C. annum var. cerasiforme were 43, 42, and 38 g, respectively. The clinical Candida isolates including C. albicans (n = 13), C. dubliniensis (n = 2), C. parapsilosis (n = 2), and C. tropicalis (n = 1); and reference strains of C. albicans (TIMML 1292 and TIMML 183), C. krusei (TIMML 1321), C. parapsilosis (TIMML 2201), and C. tropicalis (TIMML 731) were examined based on the M27-A3 guideline.

RESULTS

Aqueous and alcoholic extracts of Capsicum annum showed a minimum inhibitory concentration (MIC) range of more than 512 µg/ml against clinical and reference strains of Candida. There was no justifiable difference between the effects of these extracts on Candida species.

CONCLUSION

Both aqueous and alcoholic extracts of Capsicum annum could not exert a significant effective impact on clinical and reference strains of Candida. The difference in pepper spiciness did not show a significant role against Candida isolates. However, their possible effects might be different among other yeasts or filamentous fungi.

Changes of Gene Expression in Candida albicans Isolates from Vaginal Infections by Effects of Zinc Oxide Nanoparticles and Fluconazole

Background: There are serious challenges of drug resistance in Candida albicans infection. Therefore, it is essential to identify new antifungal agents against resistant species to effectively treat patients affected by these species. Objectives: The present study aimed to study how zinc oxide nanoparticles (ZnO-NPs) and fluconazole affected the genes encoding resistance to fluconazole (i.e., CDR2 and ERG11) and those encoding adhesins (i.e., ALS1 and HWP1) in C. albicans isolates. Methods: In this descriptive-analytic study, samples of 120 patients with vaginitis were obtained using sterile swabs. After the identification of C. albicans strains, the fluconazole-resistant candida isolates were treated with various sub-minimum inhibitory concentrations of ZnO-NPs, fluconazole, and a combination of ZnO-NPs and fluconazole. Then, the effects of ZnO-NPs and fluconazole on the expression levels of ALS1, HWP1, CDR2, and ERG11 genes were evaluated by real-time polymerase chain reaction. Results: In this study, 50 out (41.6%) of 120 species with C. albicans were isolated, and 13 (26%) of 50 species were resistant to fluconazole. The expression analysis of fluconazole-resistant C. albicans strains showed that the expression of HWP1 and ALS1 genes was decreased by 2.84 and 1.62 times (P < 0.05), respectively. Nevertheless, the expression of CDR2 increased 1.42 - fold after the treatment with fluconazole. The expression of ERG11, CDR2, HWP1, and ALS1 in isolates treated with the combination of ZnO-NPs and fluconazole was downregulated by 2.1, 5.9, 3, and 5.5 times, respectively, compared to that of the control group. Conclusions: Based on the results, ZnO-NPs are helpful for the treatment of vaginitis-related C. albicans isolates in combination with fluconazole.

Antifungal Activity of Curcuminoids and Difluorinated Curcumin Against Clinical Isolates of Candida Species

BACKGROUND

Acquired resistance to antifungals is rising particularly among Candida species. Herbal ingredients have biological and pharmacological activities, which make them potential fungicidal agents. The present study investigated the effects of curcumin (CUR) and difluorinated curcumin (CDF) on Candida species.

MATERIAL AND METHOD

CUR and CDF were examined against Candida isolates obtained from patients candidemia due to C. albicans (n = 13), C. dubliniensis (n = 2), C. parapsilosis (n = 2), and C. tropicalis (n = 1); and laboratory strains of C. albicans (TIMML 1292 and TIMML 183), C. krusei (TIMML 1321), C. parapsilosis (TIMML 2201), and C. tropicalis (TIMML 731) based on the M27-A3 guideline.

RESULTS

At the concentrations of 1-512μg/mL, none of the CDF and CUR showed a significant minimum inhibitory concentration (MIC) range against Candida isolates. There was no significant difference between the effects of CUR and CDF against Candida species.

CONCLUSION

The CUR and CDF did not exert any inhibitory effect on the growth of Candida strains. Any possible effect on other yeast and filamentous fungi needs to be further investigated.

The A756T Mutation of the ERG11 Gene Associated With Resistance to Itraconazole in Candida Krusei Isolated From Mycotic Mastitis of Cows

Candida krusei (C. krusei) has been recently recognized as an important pathogen involved in mycotic mastitis of cows. The phenotypic and molecular characteristics of 15 C. krusei clinical isolates collected from cows with clinical mastitis in three herds of Yinchuan, Ningxia, were identified by matrix-assisted laser desorption ionization–time of flight mass spectrometry. In addition to sequencing analysis, the ERG11 gene that encodes 14α-demethylases, the expression of the ERG11 gene, and efflux transporters ABC1 and ABC2 in itraconazole-susceptible (S), itraconazole-susceptible dose dependent (SDD), and itraconazole-resistant (R) C. krusei isolates was also quantified by a quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) assay. Sequencing analysis revealed three synonymous codon substitutions of the ERG11 gene including T939C, A756T, and T642C in these C. krusei clinical isolates. Among them, T642C and T939C mutations were detected in itraconazole-resistant and -susceptible C. krusei isolates, but the A756T substitution was found only in itraconazole-resistant isolates. Importantly, the expression of the ERG11 gene in itraconazole-resistant isolates was significantly higher compared with itraconazole-SDD and itraconazole-susceptible isolates (p = 0.052 and p = 0.012, respectively), as determined by the qRT-PCR assay. Interestingly, the expression of the ABC2 gene was also significantly higher in itraconazole-resistant isolates relative to the itraconazole-SDD and itraconazole-susceptible strains. Notably, the expression of ERG11 was positively associated with resistance to itraconazole (p = 0.4177 in SDD compared with S, p = 0.0107 in SDD with R, and p = 0.0035 in S with R, respectively). These data demonstrated that mutations of the ERG11 gene were involved in drug resistance in C. krusei. The A756T synonymous codon substitution of the ERG11 gene was correlated with an increased expression of drug-resistant genes including ERG11 and ABC2 in itraconazole-resistant C. krusei isolates examined in this study.

Molecular typing of multi-drug resistant Candida albicans isolated from the Segamat community, Malaysia

In the past decade, researchers have focused on the emergence of drug resistance in fungal pathogens such as Candida albicans, also considered as pathobionts that occur harmlessly in the human body but could potentially be triggered to cause diseases. The increasing rate of antifungal resistance in commensal gut fungi is alarming and should be further investigated. Here, we report seven novel MLST (Multi Locus Sequence Typing) genotypes of multi-drug resistant C. albicans isolates obtained from participants of a community study in Segamat, a district in the state of Johor, Malaysia. A total of eight C. albicans were isolated from four individuals, which were found to express high resistance against fluconazole, itraconazole, voriconazole and 5-fluorocytosine antifungals. MLST was performed to assess the clonal relatedness of these drug resistant isolates among themselves and against other strains isolated from other geographical regions. The novel MLST C. albicans sequence types suggest significant genetic changes compared to previous genotypes.

The effects of secreted aspartyl proteinase inhibitor ritonavir on azoles-resistant strains of Candida albicans as well as regulatory role of SAP2 and ERG11

BACKGROUND

Candida albicans, the main human fungal pathogen, can cause fungal infection and seriously affect people's health and life. This study aimed to investigate the effects of ritonavir (RIT) on C. albicans and the correlation between SAP2 as well as ERG11 and drug resistance.

RESULTS

Secreted aspartyl proteinases (Saps) activities and pathogenicity of C. albicans with different drug resistance were measured. M27-A4 broth microdilution method was used to analyze the drug sensitivity of RIT combined with fluconazole (FCA) on C. albicans. After that, SAP2 and ERG11 mutations were examined by polymerase chain reaction (PCR) and sequencing, and quantitative real-time PCR was utilized to determine the expression of the two genes. By analyzing pz values, the Saps activity of cross-resistant strains was the highest, followed by voriconazole (VRC)-resistant strains, FCA-resistant strains, itraconazole (ITR)-resistant strains, and sensitive strains. The pathogenicity of C. albicans in descending order was as follows: cross-resistant strains, VRC-resistant strains, ITR-resistant strains, FCA-resistant strains, and sensitive strains. With the increase of RIT concentrations, the Saps activity was gradually inhibited. Drug sensitivity results showed that there was no synergistic effect between RIT and FCA. Additionally, no gene mutation sites were found in SAP2 sequencing, and 17 synonymous mutations and 6 missense mutations occurred in ERG11 sequencing. Finally, the expression of SAP2 and ERG11 was significantly higher in the resistant strains compared with the sensitive strains, and there was a positive liner correlation between SAP2 and ERG11 messenger RNA expression (r = .6655, p < .001).

CONCLUSION

These findings may help to improve our understanding of azole-resistant mechanisms of C. albicans and provide a novel direction for clinical therapeutics of C. albicans infection.

Detection of antifungal drug-resistant and ERG11 gene mutations among clinical isolates of Candida species isolated from Khartoum, Sudan

Background:  Candida species are one of the most important opportunistic fungal pathogens that cause both superficial and systemic infections, especially in immunocompromised individuals. Considering the sharp increase in the rate of  Candida infections, and resistance to commonly used antifungal agents in the last decades; this study was conducted to determine the rate of resistance among clinical isolates of  Candida species, and to characterize some of the resistant genes among resistant isolates collected in Khartoum. 

Methods: This is a cross-sectional laboratory-based study included 100 pre-screened  Candida species isolates from Khartoum state hospitals. Chromogenic media was used for  Candida isolation and/or identification. The standard disc diffusion method was performed to investigate the susceptibility to fluconazole, itraconazole, and amphotericin. Following genomic DNA extraction, the entire  ERG11 gene was amplified from some C. albicans resistant isolates, sequenced, and further analyzed.

Results: Out of 100 clinical isolates collected, 51% were  C. albicans, followed by  C. glabrata (31%),  C. krusie (8%),  C. tropicals (5%), and C. dupliniens (5%). Resistance rate was 23% for fluconazole, 4% for itraconazole, while there were no amphotericin resistant isolates detected. C. albicans  ERG11 gene sequence reveals 15 different mutations. Among these, three (D116E, E266D, and V488I) were missense mutations; however, these substitutions do not contribute to fluconazole resistance.

Conclusion:  C. albicans was found to be the most common species. Resistance against fluconazole was observed most frequently; however, mutations in ERG11 are unlikely to be the reason behind fluconazole resistance among these isolates.