Drug-Resistant Fungus Colonizes One in Ten ICU Patients in Single-Center Survey

A multidrug-resistant fungus that health authorities rank among the most dangerous fungal threats in the world has swept through the intensive care units of a Turkish tertiary-care hospital, according to a new study published in International Microbiology. Researchers found Candidozyma auris colonization in 7 of 70 ICU patients screened on a single day, a point prevalence of 10 percent, and over the following six months identified colonization in 15 more patients and bloodstream infection in nine. Every patient whose blood cultures grew the fungus died, a stark outcome the investigators attribute partly to the advanced age and heavy burden of comorbidities in the affected cohort rather than to the infection alone.

The investigation began after routine microbiology flagged an unexpected finding in February 2025: C. auris growing in a urine culture from a patient in the hospital’s Coronary ICU. That isolate was designated the institution’s index case, and the hospital’s Infection Control Committee responded by launching a same-day, cross-sectional point prevalence survey across all nine ICUs, from Anesthesia and Internal Medicine to Cardiovascular Surgery and Neurology. Seventy patients were hospitalized across those units on the survey day, and all were included regardless of how long they had already been in intensive care.

The screening protocol followed recommendations from the United States Centers for Disease Control and Prevention. Each patient was swabbed with a single sterile swab applied sequentially to both axillary regions and both groin regions, producing a composite screening sample. Where clinically applicable, additional specimens were collected: urine samples via Foley catheter from patients with indwelling urinary catheters, and wound swabs from patients with open wounds. In total, 157 specimens reached the microbiology laboratory, comprising 70 composite swabs, 69 urine cultures and 18 wound swabs.

Identification relied on a layered diagnostic algorithm. Screening swabs were inoculated onto CHROMagar Candida Plus, a chromogenic medium on which C. auris forms light blue colonies with a characteristic blue halo, distinguishing it from related and unrelated yeasts. All yeast-like colonies were then tested with the germ tube assay to exclude the C. albicans complex, and germ tube-negative isolates were examined microscopically on cornmeal Tween 80 agar for pseudohyphae and blastoconidia morphology. Definitive species-level identification was achieved with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, or MALDI-TOF MS, which compares fungal protein spectra against validated reference databases. The authors note that conventional methods frequently misidentify C. auris as species such as C. haemulonii or Saccharomyces cerevisiae, and that MALDI-TOF MS is not universally available, making validated low-cost algorithms an important priority for resource-limited settings.

The survey results showed colonization concentrated in one unit. Five of the seven colonized patients were in the Anesthesia ICU, where 5 of 10 patients screened, or 50 percent, carried the fungus; the remaining two cases were in General ICU-1 and General ICU-2. This difference in colonization prevalence across ICUs was statistically significant, with a p value of 0.0044 by Fisher’s exact test. Of the seven colonized patients, five had positive composite swabs only, one also had a positive wound culture, and one grew the fungus from swab, urine and wound specimens alike. Positivity rates by specimen type were 10.0 percent for swabs, 1.4 percent for urine and 11.1 percent for wounds, a numerical spread that did not reach statistical significance. Across all 157 specimens, overall positivity was 6.37 percent.

After the survey, the hospital continued routine colonization screening of all newly admitted ICU patients and monitored blood cultures for six months. During that period, screening cultures detected C. auris colonization in 15 additional patients, distributed across the Anesthesia, General ICU-1, General ICU-2, General ICU-3 and Chest Diseases units. The authors interpret this rapid accumulation of colonized patients following a single index case as evidence of ongoing transmission and persistence within the ICU environment, likely aided by the fungus’s resistance to commonly used surface disinfectants, its strong biofilm formation, and its ability to survive on hospital surfaces for extended periods.

The clinical toll emerged in parallel. Over the same six months, C. auris was isolated from blood cultures of nine patients, three of whom had previously been identified as colonized. Colonized patients faced roughly a 4.5-fold higher risk of developing bloodstream infection than non-colonized patients, with three of seven colonized patients versus six of 63 non-colonized patients becoming infected, an odds ratio of 4.5 that was statistically significant at p = 0.045. The interval between colonization detection and blood culture positivity ranged from one day to approximately two months. In two of the nine patients with fungemia, recurrent bloodstream infection occurred despite antifungal therapy, one treated with amphotericin B and one with an echinocandin, with recurrences 13 and 30 days after the initial isolation, a pattern the authors suggest may reflect variable antifungal susceptibility and biofilm formation.

All nine patients with positive blood cultures died. The risk factor profile was strikingly uniform: broad-spectrum antibiotic use, prolonged ICU stay and urinary catheterization were each present in 100 percent of the fungemia cases, central venous catheters in 88.9 percent, mechanical ventilation in 55.6 percent, and parenteral nutrition in 66.7 percent. Every patient was older than 65, and hypertension and diabetes mellitus were documented in five and four patients respectively. The authors caution that the 100 percent mortality likely reflects this constellation of advanced age, prolonged intensive care exposure, multiple invasive procedures and severe underlying illness rather than the fungal infection alone; published mortality rates for C. auris candidemia generally range from 30 to 70 percent depending on population and access to therapy.

The study’s context within the global epidemiology of this pathogen underscores why the findings drew attention. C. auris, first isolated in 2009 from a patient’s external ear canal in Japan, has caused large outbreaks worldwide and was placed by the World Health Organization in its fungal pathogens of critical priority category in 2022; it was also the first fungal pathogen designated an urgent public health threat by the CDC, which issued an alert after its detection in the United States in 2016. A recent genome-scale phylogenetic analysis reclassified the organism and related species into the newly established genus Candidozyma. Comparative point prevalence figures reported elsewhere include 1.6 percent among 430 patients in one United States study, 6.6 percent in another U.S. survey, 4.5 percent and 7 percent in further reports, and rates as high as 21 percent among patients exposed to index cases in India, placing the 10 percent observed here at the higher end of the international range.

The authors emphasize that prevention rests on rapid identification of colonized patients, strict contact precautions, and effective environmental cleaning, measures that include gloves and long-sleeved gowns, dedicated or single-use non-critical equipment, and single-room placement or cohorting of colonized and infected patients. Colonization can develop within hours or days of exposure and persist for months without symptoms, yet an estimated 5 to 10 percent of known colonized individuals eventually develop invasive disease. The study’s limitations are acknowledged plainly: it is a single-center investigation with a relatively small sample, and no direct statistical comparison was made between the one-day survey and the six-month surveillance because the two datasets reflect different epidemiological contexts and patient populations. Even so, the investigators argue the work provides important early data on how quickly this organism can establish itself in intensive care settings, and they call for larger multicenter prospective studies incorporating antifungal susceptibility testing and molecular epidemiological analyses to characterize transmission pathways, resistance patterns and long-term outcomes.

Subject of Research: Candidozyma auris colonization and bloodstream infection surveillance in hospital intensive care units

Article Title: Candidozyma auris in intensive care units: A point prevalence study and six-month colonization–infection surveillance

Article References: Yiş, R., & Şenol, G. (2026). Candidozyma auris in intensive care units: A point prevalence study and six-month colonization–infection surveillance. International Microbiology. https://doi.org/10.1007/s10123-026-00902-4

Image Credits: AI Generated

DOI: 10.1007/s10123-026-00902-4

Keywords: Candidozyma auris, intensive care units, point prevalence study, colonization, fungemia, antifungal resistance, MALDI-TOF MS, infection control, nosocomial transmission, mortality, screening, surveillance