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C. auris Infection: Rare, But Raising Concerns About Pan-Resistance

CDC researchers say the infection is “globally emerging” and cases with resistance to all 3 classes of commonly prescribed antifungal drugs have been reported in multiple countries.


 

Candida auris (C. auris) infection was first detected in New York, in July 2016. As of June 2019, 801 patients have been identified in New York as having C auris —and of those, 3 had pan-resistant infection.

CDC researchers say C auris is “a globally emerging yeast.” Cases with resistance to all 3 classes of commonly prescribed antifungal drugs have been reported in multiple countries.

In New York, of the first 277 available clinical isolates, 276 were resistant to fluconazole and 170 were resistant to amphotericin B. None were resistant to echinocandins. Subsequent testing found 99.7% of 331 isolates from infected patients with susceptibilities were resistant to fluconazole, 63% were resistant to amphotericin B, and 4% were resistant to echinocandins. Three of the subsequent isolates were pan-resistant.

The first 2 of those 3 patients were > 50 years old and residents of long-term care facilities. Each had multiple medical conditions, including ventilator dependence and colonization with multidrug-resistant bacteria. Neither patient was known to have received antifungal medications before the diagnosis of C. auris infection, but both were treated with prolonged courses of echinocandins after the diagnosis. Cultures taken after echinocandin therapy showed resistance to fluconazole, amphotericin B, and echinocandins. Both patients died, but the role of C. auris in their deaths is unclear.

The researchers found no epidemiologic links between the 2 patients. They were residents at different health care facilities, neither had any known domestic or foreign travel. No pan-resistant isolates were identified among contacts or on environmental surfaces from their rooms or common equipment at the 3 facilities where they had been patients. Although C. auris was isolated from other patients, none was pan-resistant.

A retrospective review of all New York C. auris isolates turned up a third pan-resistant patient. The patient also was aged > 50 years old , had multiple comorbidities, and a prolonged hospital and long-term care stay. However, the patient received care at a third unique facility. This third patient, who died from underlying medical conditions, was also not known to have traveled recently, and had no known contact with the other 2 patients.

Isolates from all 3 patients were initially sensitive to echinocandins. Resistance was detected after treatment, indicating it emerged during treatment with the drugs. The researchers found no evidence of transmission.

Approximately 3 years after the beginning of the New York outbreak, the pan-resistant isolates still appear to be rare, the researchers say, but “their emergence is concerning.” They urge close monitoring for patients on antifungal treatment for C. auris , along with follow-up cultures and repeat susceptibility testing, especially in patients previously treated with echinocandins.

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