Discussion

C. auris is considered a major nosocomial pathogen with substantial implications for health care settings. It is a multidrug-resistant yeast capable of causing hospital outbreaks. It is also well known to cause significant morbidity and mortality among critically ill patients [15]. Since the first reported case of C. auris from Oman in 2017, there has been a rise in cases in subsequent years [16].

The aim of our study was to compare the associations, outcomes, and drug susceptibility patterns of patients with C. auris and non-_C. auris _bloodstream infections over the five-year study period from January 2018 to December 2022. The most common associations with _C. auris _bloodstream infection were prior colonization with any _Candida _species and previous contact with a health care facility, with ORs of 6.71 (95% CI, 3.26-13.80) and 5.89 (95% CI, 2.61-14.24), respectively. This aligns with global reports that _C. auris _is primarily a health care-associated pathogen with a propensity for nosocomial transmission [18]. The OR for _C. auris _bloodstream infection in patients on hemodialysis was 2.83 (95% CI, 1.42-5.64) compared with non-C. auris bloodstream infection.

The presence of CVCs was associated with a higher likelihood of non-_C. auris _bloodstream infection compared with _C. auris _bloodstream infection, with an OR of 0.15 (95% CI, 0.07-0.32). Despite a nonsignificant p-value, _C. auris _was observed in 35 (60.3%) patients admitted to critical areas compared with 67 (65.7%) patients with non-_C. auris _bloodstream infection. This is comparable to the study by Al Maani et al., in which 65.6% of patients with _C. auris _were admitted to the ICU compared with 34.4% who were admitted to medical and surgical noncritical areas [16]. Rudramurthy et al. also demonstrated that _C. auris _candidemia has a predilection toward critically ill patients [19].

In this study, the duration from admission to the first positive blood culture was significantly different between the two groups. The mean time to positivity, as defined in the Methods section, was 47.38 days in _C. auris _infection compared with 12.78 days in non-_C. auris _infection. This observation emphasizes that _C. auris _is a health care-associated infection and that prolonged hospitalization with multiple instrumentation plays a significant role in the development of bloodstream infection compared with non-_C. auris _infection. Studies have demonstrated that, unlike other Candida species, in which the source is endogenous and mainly affects the host through autoinfection, _C. auris _is transmitted through contaminated environments and equipment in health care settings [20]. This finding is also supported by our study, in which previous health care contact was significantly more common among patients with _C. auris _bloodstream infection than among those with non-_C. auris _bloodstream infection (84.5% vs 48%). The majority of _C. auris _cases occur in patients with significant comorbidities and multiple risk factors, including prolonged ICU stays, CVC use, prior antifungal therapy, recent surgery, diabetes mellitus, and exposure to broad-spectrum antibiotics [18]. _C. auris _is considered a notable pathogen due to its ability to form biofilms, which may contribute to therapeutic failure and prolonged colonization.

All isolates in the _C. auris _group demonstrated resistance to azoles, with 100% resistance observed. The azoles tested in our cohort were fluconazole and voriconazole. In contrast, 61 isolates in the non-_C. auris _group were susceptible to azoles. Azole resistance is extremely high and has been demonstrated in multiple studies. Deshkar et al. demonstrated 84% azole resistance among _C. auris _isolates in their study. Other azoles, such as posaconazole and itraconazole, also demonstrated high MICs, indicating resistance [21]. In a recent study, da Silva et al. evaluated the susceptibility of _C. auris _isolates across clades and demonstrated 94% and 96% azole resistance in clades I and III, respectively [22]. For echinocandins, all three agents, namely micafungin, caspofungin, and anidulafungin, were tested in our laboratory. One C. auris isolate was resistant to all three drugs, whereas all non-_C. auris _isolates were susceptible. Other studies have also found that _C. auris _generally exhibits good susceptibility to echinocandins. None of the _C. auris _isolates demonstrated resistance to echinocandins, as reported by Sayeed et al. [19]. In the Kuwaiti study, one isolate was found to be resistant to echinocandins; however, that isolate was identified from a urinary source [23].

When comparing susceptibility to polyenes, for which amphotericin B was the tested drug in our study, 56.9% of C. auris isolates were susceptible compared with 100% susceptibility among isolates in the non-C. auris group. A study from the same region also demonstrated 23.2% resistance to polyenes among _C. auris _isolates [23]. Similarly, a comparative study conducted in Pakistan reported polyene resistance rates of 3.7% and 0% in the _C. auris _and non-_C. auris _groups, respectively [18]. This contrasted with a study from the Indian subcontinent, where 94% of _C. auris _isolates were susceptible to amphotericin B [21]. Although patients with _C. auris _had prolonged hospitalization compared with patients with non-_C. auris _bloodstream infection, the outcome defined as death during the same admission episode was not significantly different between the two groups. A similar observation was reported in a study conducted in Pakistan by Sayeed et al. [18].

Limitations

This study may be limited by its single-center design in Oman. The comparison of associations between the two groups lacked multivariate analysis, which may represent a limitation of the study. Not all isolates underwent antifungal susceptibility testing, and MICs for each antifungal drug were not available. However, the lack of clinical breakpoints for C. auris in existing guidelines poses difficulty in assessing treatment outcomes.