Detection of ERG11 Transcripts in Fluconazole-Resistant <i>Candida albicans</i> Isolates from Patients with Mucosal Candidiasis in Zahedan, Iran: A Cross-sectional Laboratory Study

Abstract

Background: Mucosal candidiasis is a common fungal infection, particularly among individuals with predisposing conditions. Increased exposure to azole antifungal agents has contributed to reduced fluconazole susceptibility in Candida isolates. Several molecular mechanisms may contribute to azole resistance, including alterations in the ergosterol biosynthetic pathway, changes in ERG11 expression or sequence, and increased drug efflux activity. Objectives: This study aimed to determine the frequency of fluconazole resistance among Candida albicans isolates recovered from patients with mucosal candidiasis in Zahedan, Iran, and to evaluate the detection of ERG11 transcripts using conventional reverse-transcription polymerase chain reaction (RT-PCR). Methods: This laboratory-based cross-sectional study was conducted in 2018 at Bu-Ali Hospital and at the Obstetrics and Gynecology Clinic of Nabi Akram Hospital in Zahedan, Iran. A total of 200 patients were enrolled according to predefined eligibility criteria. Mucosal specimens were cultured, and C. albicans was identified using conventional mycological methods and chromogenic culture. Fluconazole susceptibility was assessed using the Clinical and Laboratory Standards Institute (CLSI) disk-diffusion method with 25-μg fluconazole disks. RNA was extracted from all 27 fluconazole-resistant C. albicans isolates, converted to complementary DNA (cDNA), and subjected to conventional RT-PCR using ERG11-specific primers. ACT1 served as the internal amplification control. Susceptible clinical isolates were not assessed by RT-PCR. Results: Among the 200 participants, C. albicans was identified in 39 samples (19.5%; 95% confidence interval [CI], 14.6 - 25.5%). Of the 39 C. albicans isolates, 27 (69.2%; 95% CI, 53.5 - 81.9%) were classified as fluconazole-resistant according to the susceptibility criterion used in the study. Conventional RT-PCR generated an ERG11-specific amplicon in 18 of the 27 resistant isolates. Conclusions: ERG11 transcripts were detected in a subset of the resistant isolates; however, conventional RT-PCR cannot quantify ERG11 overexpression or establish that ERG11 expression is responsible for phenotypic fluconazole resistance. Future studies using quantitative real-time RT-PCR, standardized expression analyses, and evaluation of additional resistance mechanisms are warranted. Simple, cost-effective methods, such as disk diffusion, used alongside molecular analyses, may help control the spread of drug resistance.