Beyond minimum inhibitory concentrations: Integrating molecular resistance testing for equitable management of vaginal candidiasis.

OBJECTIVE

Vulvovaginal candidiasis (VVC) affects 75% of women globally, with 5-8% experiencing recurrent episodes in which molecular resistance mechanisms have evolved beyond the conventional minimum inhibitory concentration (MIC) testing capabilities. This perspective examined the molecular evolution of antifungal resistance in vaginal Candida isolates and advocates for integrating molecular diagnostics into clinical practice to address the growing disconnect between phenotypic susceptibility testing and clinical outcomes.

METHODS

A targeted literature review was conducted using PubMed spanning 2000-2025, focusing on molecular resistance mechanisms in Candida species. Primary search terms included "Candida resistance," "vulvovaginal candidiasis," "efflux pumps," "ERG11 mutations," and specific transcription factors (TAC1, MRR1, PDR1). Eighteen representative studies demonstrating key evolutionary events in resistance mechanisms were analyzed chronologically.

RESULTS

Three distinct evolutionary phases of antifungal resistance emerged: efflux overexpression (2004-2006), regulatory diversification (2007-2016), and network synergy (2019-2025). Current clinical isolates harbor combined resistance mechanisms, including ergosterol biosynthesis gene 11 mutations (Y132F, K143R) and efflux pump overexpression (Candida Drug Resistance protein 1 [CDR1], CDR2, and multidrug resistance 1 [MDR1]), regulated by the transcription factors TAC1 and MRR1. Evidence from African surveillance demonstrates global distribution of these mechanisms, with C. auris outbreaks in Kenya (38% of candidemia cases) and South Africa reaching alarming mortality rates. These molecular changes often precede phenotypic resistance manifestation, creating diagnostic blind spots where isolates appear "susceptible" by MIC testing but demonstrate clinical treatment failure.

CONCLUSIONS

Integrating polymerase chain reaction-based molecular diagnostics targeting key resistance genes represents a paradigm shift toward proactive resistance detection and personalized antifungal therapy, addressing healthcare equity in resource-limited settings where VVC/ recurrent VVC burden is high.