A recent study published in Emerging Infectious Diseases reported an outbreak involving Candida auris (C. auris) in Israel.
Study: Nationwide Outbreak of Candida auris Infections Driven by COVID-19 Hospitalizations, Israel, 2021–2022. Image Credit: KaterynaKon/Shutterstock.com
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C. auris is a fungal pathogen resistant to drugs and has emerged as a causal agent of nosocomial outbreaks over the past decade. In Israel, five cases of C. auris infection were reported in 2014-15.
Subsequently, surveillance efforts were initiated, and clinical isolates were referred to a national laboratory for further testing. While surveillance indicated a low incidence, the number of isolates has increased since January 2021.
About the study
In the present study, researchers surveyed infections associated with C. auris in Israel to examine the microbiological and clinical characteristics and identify the factors driving the epidemiologic change. The study included medical facilities reporting at least one clinical isolate of C. auris from January 2014 to May 2022.
The team obtained data on comorbidities, demographics, prior exposure to antimicrobials, mechanical ventilation use, and infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or drug-resistant pathogens. Clinical outcomes included hospitalization and intensive care duration, mechanical ventilation use, and in-hospital mortality.
Polymerase chain reaction and sequencing of ribosomal DNA’s internal transcribed spacer (ITS) and D1/D2 regions were performed. Antifungal drug susceptibility was tested by broth microdilution.
Tested drugs were fluconazole, voriconazole, anidulafungin, amphotericin B, and itraconazole. Multi-locus sequence typing was performed to determine the genetic relatedness among isolates.
Overall, 209 C. auris isolates were reported over eight years. Twenty-four patients were detected between May 2014 and December 2020. However, the incidence of C. auris infections spiked in 2021, with 120 cases reflecting a 30-fold increase relative to the previous year. Of the 185 isolates identified from January 2021 onwards, most (93%) were from four hospitals (H1 – H4).
H1 reported 128 C. auris isolates. Repeat cultures in 152 patients indicated C. auris colonization for 14 days. C. auris incidence in 2021-22 corresponded with the surge in coronavirus disease 2019 (COVID-19) cases.
Surges in C. auris cases occurred in January-March 2021, June-November 2021, and January-May 2022, synchronous with the Alpha, Delta, and Omicron waves, respectively.
Most C. auris cases (88%) in the Alpha wave had SARS-CoV-2 infection, which declined to 22% and 6.2% during Delta and Omicron waves, respectively. The team typed 22 C. auris isolates collected before December 2020; most isolates (82%) belonged to clade IV, followed by clades III and II, and of the 43 isolates typed beginning 2021, 24, 11, and eight belonged to clades III, IV, and I, respectively.
The antifungal susceptibility rates were 15.6%, 79.6%, 86.4%, 98% for fluconazole, voriconazole, amphotericin B, and anidulafungin, respectively. Twenty-one isolates were fluconazole- and amphotericin B-resistant, while two were anidulafungin-, amphotericin B-, and fluconazole-resistant. All clade III isolates were fluconazole-resistant compared to 63% of the remaining isolates.
Overall, 177 cases had available clinical data; 30% had dementia, and half showed a functional impairment. Mechanical ventilation was required for 78% of patients. More than half the patients had carriage or infection with other pathogens. COVID-19 was documented in 41 patients before contracting C. auris in the same hospital, many (73%) of whom had a critical illness.
Half of the COVID-19 patients received remdesivir, and nearly all received corticosteroids. There were no differences in mechanical ventilation use to COVID-19 status. However, COVID-19 patients had lower dementia rates, fewer comorbidities, and better functional status at baseline.
In total, 70 in-hospital deaths occurred. The researchers further assessed C. auris outbreak evolution in three hospitals (H1 – H3).
The fungal infection was first detected in COVID-19 patients on mechanical ventilation in H1, followed by mechanically ventilated non-COVID-19 patients. There was a similar pattern in H2 but to a smaller extent. In H3, the fungal infection was mainly detected in patients on mechanical ventilation, regardless of COVID-19.
The study reported an ongoing C. auris infection and colonization in Israeli hospitals. A 30-fold increase in the annual incidence of C. auris infections was observed in 2021.
Clades I and III were not circulating in Israel pre-2021, suggesting importation events. COVID-19 and mechanical ventilation were identified as the drivers of the ongoing healthcare-associated C. auris dissemination.
Surveillance efforts and infection control measures should continue, focusing on critical patients requiring mechanical ventilation.