Context & Concern
- Candida tropicalis is a major fungal pathogen in India and globally, with a mortality rate of 55–60%.
- Increasing cases of drug-resistant C. tropicalis infections are being observed in clinical settings.
- Azole antifungals like fluconazole and voriconazole are becoming less effective.
Relevance : GS 2(Health) ,GS 3(Science)
Key Finding
- A study published in PLoS Biology links azole-resistance in C. tropicalis to the widespread agricultural use of the fungicide tebuconazole.
- Tebuconazole, a triazole fungicide, accumulates in the environment and triggers cross-resistance in clinical fungal strains.
Mechanism of Resistance: Ploidy Plasticity
- Resistant strains showed aneuploidy: abnormal chromosome numbers (haploid to triploid).
- These chromosomal alterations enhance drug resistance but reduce growth rate in drug-free environments.
- Resistant strains showed:
- Duplications (e.g., of TAC1 gene → overproduction of drug-efflux proteins).
- Deletions (e.g., of HMG1 gene → enhanced ergosterol synthesis and drug resistance).
Public Health Implications
- Resistant strains were more virulent in mice, even under antifungal treatment.
- Shows how agricultural misuse of antifungals can create clinical superbugs, threatening human health.
- Highlights interconnectedness of environment, agriculture, and public health (One Health concept).
Serendipitous Discoveries
- First-time discovery of stable haploid strains of C. tropicalis — capable of mating, increasing potential for genetic spread of resistance.
- Two naturally haploid clinical strains were also found in global genome data.
Larger Message
- The study warns against reckless use of triazoles in agriculture, which may drive antifungal resistance in human pathogens.
- It echoes the warning: “Sow the wind, reap the whirlwind” — stressing unintended consequences of unsustainable practices.
