Materials and methods

This retrospective observational cohort study was conducted at Sultan Qaboos University Hospital over a five-year period from January 2018 to December 2022. All adult patients with Candida bloodstream infection during the study period were included. Patients were identified from the electronic records of the microbiology laboratory through the Hospital Information System. All episodes of bloodstream infection caused by _Candida _species during the study period were included. Demographic, clinical, and microbiological data were collected from the electronic patient records using a predesigned pro forma. Identification of _Candida _species in the laboratory was performed using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (Bruker Corporation, Billerica, MA, USA). Antifungal susceptibility testing was performed using Sensititre YeastOne (Trek Diagnostic Systems Ltd, East Grinstead, UK). The obtained minimum inhibitory concentrations (MICs) were interpreted based on the CDC tentative breakpoints for _C. auris _[17].

The inclusion criteria were all adult patients (18 years or older) with a first episode of bloodstream infection caused by Candida species during the study period and all hospitalized patients with bloodstream infection caused by a single _Candida _species during the study period. The exclusion criteria were patients with more than one episode of _Candida _bloodstream infection during the study period, for whom subsequent episodes were excluded; patients with bloodstream infections caused by dual _Candida _species during the study period; and patients with missing data in the Hospital Information System.

The study cohort comprised 182 episodes of bloodstream infection caused by _Candida _species. Of these, 12 repeat admissions during the study period, seven episodes of dual-species _Candida _bloodstream infection, and three patients with missing data in the electronic patient record were excluded. A total of 160 patients constituted the study cohort. These patients were divided into two groups to achieve the objectives of the study. The first group comprised patients with _C. auris _bloodstream infection (the _C. auris _group). The second group, referred to as the non-_C. auris _group, included all patients with bloodstream infections caused by other _Candida _species. The study was approved by the Hospital Medical Research Ethics Committee (reference number SQU-EC/116/2023; MREC #2997).

The collected data were entered into a Microsoft Excel spreadsheet (Microsoft Corporation, Redmond, WA, USA). Descriptive statistical methods, including medians and percentages, were used where appropriate. Comparisons between the two groups were performed using IBM SPSS Statistics for Windows, version 22.0 (released 2013; IBM Corp., Armonk, NY, USA) for data analysis. A p-value of <0.05 was considered statistically significant.

The definitions used in the study were as follows. Time to positivity was defined as the number of days from hospitalization to the first positive blood culture for _Candida _species. Previous health care contact was defined as any contact with the health care system within the previous 90 days. Prior colonization was defined as a positive culture for _Candida _species from urine or from rectal and nasal swabs obtained for routine screening for methicillin-resistant Staphylococcus aureus and multidrug-resistant organisms, according to hospital protocol, or a positive culture for _Candida _species from urine, respiratory specimens, or sterile body fluids, such as ascitic or pleural fluid. Critical areas included the ICU, high dependency unit, hematology wards, including the bone marrow transplant unit, and the coronary care unit. Presence of hemodialysis vascular access or a CVC was defined as the presence of either or both devices during the episode of the first positive blood culture for _Candida _species. Steroid use was defined as receipt of high-dose corticosteroids (more than 40 mg of prednisone for more than two weeks) within the previous 30 days or current receipt of corticosteroids, including pulse steroid therapy, during the index admission. Bacteremia was defined as the presence of bloodstream infection caused by a bacterium during the current admission.