Section 2.5: Severe Candida auris Infections: Risk Factors & Resistance Patterns

Candida auris exhibits multidrug resistance, environmental persistence, and high transmissibility, making it a major nosocomial pathogen in global ICUs, with crude candidemia mortality rates of 30%–60% [12]. Multiple outbreak reports and extensive research have clarified its risk factors and resistance patterns. Compared to non-auris Candida species (e.g., C. albicans, C. tropicalis), historical data were limited; however, newly published 2025 studies provide updated evidence-based insights.

1. Epidemiology of Critical C. auris Infection

C. auris differs significantly from non-auris species epidemiologically. It demonstrates superior environmental tolerance and nosocomial transmission capability, surviving long-term in healthcare settings and triggering ICU cluster outbreaks. Its resistance to common disinfectants and antifungals (azoles, echinocandins, polyenes) is more pronounced, with some strains approaching pan-resistance, greatly complicating infection control. These traits make it a more formidable global public health challenge than traditional Candida species [3, 5].

A 2025 retrospective cohort study in Critical Care (Eastern India ICU, 2020–2023, n=267 adult candidemia cases) found C. auris accounted for 14.23%. No significant differences were observed in age, sex, APACHE II scores, nutritional risk, organ failure rates, or comorbidities (diabetes, hypertension, CKD, COPD) between groups; however, the C. auris group had a significantly lower median SOFA score on admission (7 vs. 8). Crude mortality was comparable [31.62% (C. auris) vs. 34.51% (non-auris)].

A 2025 Turkish study further clarified clinical characteristics. Among 182 ICU patients, the C. auris group showed significantly higher fluconazole resistance, prior antifungal exposure, catheterization rates, and ICU LOS, though short- to long-term mortality did not differ significantly [7]. Another study (n=437) found 30-day mortality for C. auris candidemia (63.3%) was lower than C. albicans (82.5%) and other Candida species (75.5%) [8]. These trends align with Indian data, indicating C. auris prevalence (14.23%–20.59%) and mortality (31.62%–63.30%) remain within known ranges, but clinical features and prognosis exhibit geographic variability [9].

2. Risk Factors for Critical C. auris Infection

A 2024 NEJM study and a 2025 review summarize risk factors: advanced age, comorbidities (diabetes, malignancy), invasive procedures (catheterization), broad-spectrum antibiotic exposure, and prolonged ICU stays [3, 4]. The synergistic effect of these medical and environmental factors elevates infection risk. Notably, skin colonization is a critical precursor; ~25% of colonized patients progress to candidemia. Prior antifungal exposure, ECMO use, and lower SOFA scores are associated with significantly higher mortality (87.23% vs. 61.22%), with MDR bacterial co-infection and mechanical ventilation as independent mortality predictors [10].

A 2025 Chinese comparative study further delineated risk factors. Turkish data indicate SOFA score is a consistent independent mortality predictor, and C. auris infection correlates with increased use of ceftazidime-avibactam, colistin, and longer catheter dwell times [7]. Indian studies link C. auris candidemia to prolonged LOS and higher SOFA scores [9]. Greek research found C. auris patients with MDR bacterial co-infections had significantly higher mortality vs. those without [11].

A 2025 Critical Care study revealed that after adjusting for invasive procedures and severity scores, multivariate analysis identified increasing age (OR=1.10, P=0.0003) and female sex (OR=16.35, P=0.012) as independent predictors of C. auris infection. This provides new stratification criteria for identifying high-risk populations in ICU candidemia. Geographic variations in risk factors suggest local clinical practices and care standards influence epidemiology, with female sex as a risk factor warranting further mechanistic investigation.

3. Revisiting Resistance Patterns in Critical C. auris Infection

MDR and XDR phenotypes drastically increase treatment difficulty [1]. A 2025 Chinese study reported 5 mixed-infection cases involving different genetic clades (I and II) or intra-clade variants. These strains differed significantly in colony morphology, biofilm formation, protease activity, and survival adaptability, suggesting mixed infections may exacerbate clinical management through ecological niche differentiation and promote MDR development [14]. Molecular studies reveal specific Taclb and homologous transcription factor mutations (e.g., Candida albicans Tacl) not only mediate fluconazole resistance but also upregulate ABC transporters (e.g., Cdr1), causing cross-resistance to novel agents like manogepix, posing new challenges for combination strategies [15].

C. auris resistance mechanisms are more complex and widespread than non-auris species. 2025 data show East Indian isolates exhibit 94.7% fluconazole resistance, 39.5% amphotericin B resistance, and 7.9% echinocandin resistance; non-auris species only show fluconazole resistance, with no echinocandin resistance [6]. Greek and South Indian data are more severe: C. auris is highly resistant to azoles, with some strains resistant to echinocandins, and regional isolates showing pan-resistance across all three major classes [11, 13]. These differences highlight geographic resistance patterns, but the global trend shows escalating MDR, with emerging pan-resistant strains demanding urgent attention.

Treatment Stratification:

  • Asymptomatic colonization: No prophylaxis recommended.

  • Invasive infection: Guided by drug susceptibility testing (DST). Azole resistance (efflux pump overexpression or ERG11 mutation) → class switch. Echinocandins (e.g., caspofungin) remain first-line due to low resistance. Echinocandin resistance (FKS1 mutation) → switch to polyenes (liposomal amphotericin B) or novel triterpenoids (olafungin).

  • Complex infections (biofilm-associated or XDR): Combination therapy (e.g., amphotericin B + echinocandin) + complete device removal.

  • Novel agents (isavuconazole) and investigational efflux pump inhibitors offer additional options. Efficacy relies on rapid diagnostics, precise DST, and strict infection control [4, 9].

4. Summary

The core risks associated with C. auris infection stem from its robust skin colonization capacity, exceptional adaptability to healthcare environments, and widespread high-level antifungal resistance. To effectively mitigate this threat, precise prevention and control strategies must be implemented: rigorous environmental and medical device disinfection, strict adherence to aseptic techniques during invasive procedures, avoidance of antifungal drug misuse, and adherence to DST-guided precision therapy. Combination regimens should be employed when clinically indicated. Through these comprehensive measures, the risk of nosocomial C. auris transmission and associated mortality can be substantially reduced.
(Wang Jinfeng, Wang Ruilan, Shanghai First People’s Hospital)

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