Deadly Drug Resistant Fungal Infection Outbreak Causing Concern In U.S.

A highly drug-resistant deadly fungal infection, first warned against by U.S. health officials last summer, has been cropping up in hospitals around the country. Over 30 patients have been diagnosed with the emerging pathogen Candida auris since that time, with 28 of the 35 documented U.S. cases located in New York state., according to the CDC.

It is difficult to know just how dangerous the fungus is, since thus far it has mostly infected patients who were already seriously ill, but the majority of people diagnosed with Candida auris have died.

First reported in 2009, the fungus has been linked to invasive infections in nine countries, including the United States. It has caused at least two hospital outbreaks involving more than 30 patients each.

Invasive Infections

In a recent study, microbiologists at Case Western Reserve University School of Medicine provided new details pertaining to C. auris drug resistance and growth patterns. Based on specimens collected from around the globe, the comprehensive study also provides evidence that a new investigational drug (SCY-078) may help to cure these infections.

Professor Mahmoud Ghannoum, PhD, MBA, FIDSA, of the Center for Medical Mycology in the Department of Dermatology at Case Western Reserve School of Medicine, said:

“This emerging fungal species has started to infect patients globally, causing invasive infections that are associated with a high death rate. It is multidrug-resistant, and some strains isolated from patients are resistant to all commercially available antifungal drugs. Multidrug-resistance used to be reported for bacteria only, and now we must add fungi to the list.”

Candida auris

People who develop invasive candidiasis are often already sick from other medical conditions, so it can be difficult to know which symptoms are related to a Candida infection. However, the most common symptoms of invasive candidiasis are fever and chills that don’t improve after antibiotic treatment for suspected bacterial infections. Other symptoms can develop if the infection spreads to other parts of the body, such as the heart, brain, eyes, bones, or joints.

Previous studies have shown SCY-078 is effective against other Candida species that cause catheter-associated infections, including C. albicans and C. tropicalis. Said Ghannoum,

“This drug is especially promising because of its broad anti-Candida activity, including activity against drug-susceptible and resistant strains.”

The study also reports that C. auris does not germinate and produce spores like other fungi, a surprise given its ability to rapidly spread in hospitals. The researchers also discovered only certain strains produce destructive enzymes that commonly help fungi establish infections in body tissue. Despite these apparent weaknesses, the fungus is able to maintain extreme drug-resistance and infect patients.

Eradication Is Challenging

In some patients, C. auris, unlike previously known yeast infections, can enter the bloodstream and spread throughout the body, causing serious invasive infections.

Another reason the CDC is raising concern is that the fungus is difficult to identify with standard laboratory methods, and it can be misidentified in labs without specific technology. Misidentification may lead to inappropriate treatment.

C. auris has caused bloodstream infections, wound infections, and ear infections. It also has been isolated from respiratory and urine specimens, but it is unclear if it causes infections in the lung or bladder. It is resistant to most antifungal drugs commonly used to treat Candida infections.

The Centers for Disease Control and Prevention is actively tracking C. auris infections. Said Ghannoum,

“Eradication of Candida auris from hospitals is very difficult and in some cases has led to closing hospital wards.”

People staying in hospitals for extended periods of time are most at risk. Laboratory workers who identify the species in a patient sample are encouraged to contact state or local public health authorities, or candidaauris@cdc.gov.

Emily Larkin et al
The Emerging: Characterization of Growth Phenotype, Virulence Factors, Antifungal Activity, and Effect of SCY-078, a Novel Glucan Synthesis Inhibitor, on Growth Morphology and Biofilm Formation
Antimicrobial Agents and Chemotherapy (2017). DOI: 10.1128/AAC.02396-16

Top Image: Candidiasis psuedohyphae and budding yeast forms. Credit: Yale Rosen CC-BY

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