P113 Expression profile of ABC and MFS multi-drug transporter genes in terbinafine- and fluconazole-resistant Trichophyton spp.
Authors: Shaw Dipika , Dogra Sunil , Narang Tarun , Ghosh Anup , Kaur Harsimran , Chakrabarti Arunaloke , Rudramurthy Shivaprakash M 
Published: September 2022

Abstract

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PM

Objectives
Over the past few decades, an unprecedented increase in recalcitrant and chronic dermatophytosis with atypical clinical presentations have been noted in the Indian subcontinent. Recent studies have reported Trichophyton mentagrophytes/interdigitale complex as predominant etiological agent of chronic/recurrent dermatophytosis followed by T. rubrum. Multiple factors, including unregulated use of antifungal drugs, poor compliance to treatment, and irrational fixed-drug combinations are associated with emerging resistance. However, molecular studies investigating the underlying mechanisms related to terbinafine and fluconazole resistance in dermatophytes are sparse.
The present study was designed to explore the role of multidrug efflux transporters in terbinafine- and fluconazole-resistant T. mentagrophytes/interdigitale complex and T. rubrum.

Methods
The expression of MDR transporter genes was evaluated in 36 isolates with terbinafine resistance (with or without F397L or L393F mutation in squalene epoxidase gene, SE) of T. mentagrophytes/interdigitale complex (n = 26), and T. rubrum (n = 10) isolates along with 16 susceptible wild-type isolates of T. mentagrophytes/interdigitale complex (n = 10), and T. rubrum (n = 6) isolates. In addition, 19 fluconazole-resistant T. mentagrophytes/interdigitale complex (n = 11), and T. rubrum (n = 8) isolates along with 13 susceptible T. mentagrophytes/interdigitale complex (n = 9), and T. rubrum (n = 4) were also included. Quantitative real-time PCR (qRT-PCR) was used to evaluate the expression of ABC transporter (MDR1, MDR2, MDR3, MDR4, and MDR5) and MFS transporter genes (MFS1 and MFS2).

Results
In terbinafine-resistant T. mentagrophytes/interdigitale complex, the mean expression of MDR1 and MDR2 was 4.98 and 5.27-fold in isolates with wild-type SE, compared with 0.64 and 1.04-fold in isolates with non-wildtype SE gene (P &lt;.0001) and susceptible isolates at 0.4, and 0.88-fold (P &lt;.0001), respectively. For MFS1 gene, 3.4-fold-change expression was noted in isolates with wild-type SE compared with 1.51-fold in isolates with non-wild type SE (P &lt;.001). In resistant isolates with non-WT SE, the upregulation of the SE gene was noted at 6.3-fold compared with 1.8-fold in isolates with wild-type SE (P &lt;.001), and 0.63-fold in susceptible isolates (P &lt;.0001). However, there was no significant upregulation of MDR3, MDR4, MDR5, and MFS2 genes among the three groups. In terbinafine-resistant T. rubrum, the mean inducible expression of MDR1 was significantly higher in isolates with wild-type SE at 3.88-fold compared to isolates with non-wild type SE at 0.5-fold (P &lt;.05) and susceptible isolates at 0.33-fold (P &lt;.01). Only resistant isolates with wild-type SE showed significant up-regulation of MDR2 (P &lt;.01) compared to susceptible isolates. Other genes, MDR3, MDR4, MDR5, MFS1, MFS2, and SE, did not show substantial overexpression among the groups (Resistant WT vs. Resistant NWT vs. susceptible WT). In fluconazole-resistant and -susceptible isolates of T. mentagrophytes/interdigitale complex, and T. rubrum, similar findings were observed. In both the species, the mean inducible expression of MDR1, MDR2, and MDR3 was significantly higher (P &lt;.05) in resistant isolates compared to susceptible isolates.

Conclusion
In conclusion, this study demonstrates the overexpression of MDR1 and MDR2 in terbinafine-resistant Trichophyton spp. isolates lacking drug-target gene mutation, suggesting the role of multidrug transporters in resistance. This study also suggests the importance of MDR2, and MDR3 transporter genes in imparting fluconazole resistance in Trichophyton spp.