Creation and Internal Validation of a Clinical Predictive Model for Fluconazole Resistance in Patients With Candida Bloodstream Infection

Treatment of invasive candidiasis in the era of Candida resistance

PURPOSE OF REVIEW

The increasing incidence of drug-resistant Candida brings a new challenge to the treatment of invasive candidiasis. Although cross-resistance among azoles and echinocandins was generally uncommon, reports of multidrug-resistant (MDR) Candida markedly increased in the last decade. The purpose of this review is to understand mechanisms and risk factors for resistance and how to tackle antifungal resistance.

RECENT FINDINGS

The paper describes the action of the three main classes of antifungals - azoles, echinocandins and polyenes - and Candida's mechanisms of resistance. The current evolution from cross-resistance to multiresistance among Candida explains the modern glossary - multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) - imported from bacteria. MDR Candida most commonly involves acquired resistance in species with intrinsic resistance, therefore it mostly involves C. glabrata, C. parapsilosis, C. krusei, C guilliermondii or C. auris , which is intrinsically multidrug resistant. Finally, strategies to tackle antifungal resistance became clearer, ideally implemented through antifungal stewardship.

SUMMARY

Avoiding antifungal's overuse and selecting the best drug, dose and duration, when they are needed, is fundamental. Knowledge of risk factors for resistance, microbiological diagnosis to the species, use of susceptibility test supported by antifungal stewardship programs help attaining effective therapy and sustaining the effectiveness of the current antifungal armamentarium.

The Risk Factors and Mechanisms of Azole Resistance of Candida tropicalis Blood Isolates in Thailand: A Retrospective Cohort Study

In recent decades, an epidemiological shift has been observed from Candida infections to non-albicans species and resistance to azoles. We investigated the associated factors and molecular mechanisms of azole-resistant blood isolates of C. tropicalis. Full-length sequencing of the ERG11 gene and quantitative real-time RT-PCR for the ERG11, MDR1, and CDR1 genes were performed. Male sex (odds ratio, 0.38), leukemia (odds ratio 3.15), and recent administration of azole (odds ratio 10.56) were associated with isolates resistant to azole. ERG11 mutations were found in 83% of resistant isolates, with A395T as the most common mutation (53%). There were no statistically significant differences in the expression of the ERG11, MDR1, and CDR1 genes between the groups resistant and susceptible to azole. The prevalence of azole-resistant isolates was higher than the usage of antifungal drugs, suggesting the possibility of environmental transmission in the healthcare setting. The unknown mechanism of the other 17% of the resistant isolates remains to be further investigated.