Las Vegas Sun

March 28, 2024

UNLV-SNWA study sheds light on detecting dangerous fungal superbug

Candida Auris Wastewater

Brian Ramos

Dr. Katherine Crank, postdoctoral researcher at the Southern Nevada Water Authority study samples of local wastewater for traces of the Candida auris fungus that has been found in hospitals across the United States, including Las Vegas, NV. Tuesday, April 18, 2023. Brian Ramos

Public health officials across the United States and elsewhere have a new method to turn to in detecting a widespread, dangerous fungus, thanks to a recent study in Las Vegas conducted by a team that included UNLV and Southern Nevada Water Authority researchers.

Candida Auris Wastewater

Researchers Casey Barber, left, Katerina Papp, Dr. Katherine Crank and Dr. Daniel Gerrity at the Southern Nevada Water Authority study samples of local wastewater for traces of the Candida auris fungus that has been found in hospitals across the United States, including Las Vegas, NV. Tuesday, April 18, 2023. Brian Ramos Launch slideshow »

During a 10-week study, the researchers found that sewersheds — areas where all the sewers flow to a single endpoint — serving health care facilities in the Las Vegas Valley showed a higher concentration of Candida auris — the drug-resistant, potentially fatal superbug that the Centers for Disease Control and Prevention calls “an emerging fungus that presents a serious global health threat.”

The team’s findings were published in the journal Environmental Science and Technology.

The superbug is especially prevalent in Nevada with a nation-leading 384 reported cases in 2022, according to the CDC.

The C. auris fungus can spread in health care settings through contact with contaminated environmental surfaces or equipment, or from person to person, the CDC said.

The fungus has been found in 22 hospitals and nursing homes across Southern Nevada since 2021, according to the study.

Wastewater samples were collected from seven sewersheds and analyzed for the presence of C. auris last summer. The fungus was detected in 72 of 91 samples, with higher detection frequencies in sewersheds serving health care facilities that experienced superbug cases.

Researchers also collected one sample of effluent disinfected at a wastewater treatment facility and two drinking water sources — the Las Vegas Wash and the Lake Mead intake, all of which tested negative for C. auris. These “control samples” suggest that C. auris is not present in treated wastewater effluent, effluent-impacted surface water (e.g., Las Vegas Wash), or other source waters (e.g., Lake Mead and the Colorado River).

“This is just a first step in understanding how wastewater surveillance might be able to be used in public health surveillance as well,” said Casey Barber, a graduate intern at the Southern Nevada Water Authority and doctoral student in UNLV’s School of Public Health. and one of the researchers working on the study.

Participating from the SNWA along with Barber were Daniel Gerrity, principal research microbiologist; Katherine Crank, a postdoctoral researcher; and Katerina Papp, microbiologist. The study also drew researchers from the Yuma Center of Excellence for Desert Agriculture at the University of Arizona and the Utah Department of Health and Human Services, Utah Public Health Laboratory.

The Southern Nevada team was already collecting wastewater samples to monitor local levels of COVID-19, which they’ve done since 2020, and other pathogens.

Utilizing wastewater surveillance can help communities detect viruses and fungal outbreaks earlier, which would allow public health teams to “identify high-priority locations for individual screening or increased infection control education to prevent potential spread,” Barber said.

But, the study cautions, “Further research is needed to understand the fate and transport of C. auris through the sewer system, as this information is critical for the potential use of C. auris as an early warning signal, a means of estimating incidence/prevalence, or a means of confirming clearance from a facility or community.”

Although it normally presents as a type of yeast, the fungus can cause severe invasive infections throughout the body when it enters the bloodstream. Fever, chills, sweats and low blood pressure are the most common symptoms of a C. auris infection. More than 1 in 3 patients infected with C. auris dies, the CDC said.

It can be difficult to identify with regular laboratory equipment, grows on both moist and dry surfaces and is resistant to many of the common antifungal drugs, making the subsequent infections harder to treat, the CDC said.

People who have recently spent time in nursing homes and have lines and tubes that go into their body — breathing tubes, feeding tubes and central venous catheters — are at highest risk for the infection, according to the CDC.

“The rapid rise and geographic spread of cases is concerning and emphasizes the need for continued surveillance, expanded lab capacity, quicker diagnostic tests, and adherence to proven infection prevention and control,” CDC epidemiologist Dr. Meghan Lyman said in a statement.

Gerrity said the group’s wastewater study gives public health officials in Southern Nevada more data so they could understand how widespread the outbreak was and ask health care facilities to increase their own monitoring of the fungus.

“Over time, this tool is going to improve, and people are going to start putting those pieces together a lot faster so that when something hits the scene, we have all those pieces right at the beginning so that we can give all the information that’s needed,” Gerrity said.

Discovering that wastewater analysis could be used to find C. auris was only the first step and that collaborative efforts were needed to “get the full picture,” Barber said.

“At this time, we don’t know what that means in terms of relating back to cases or colonizations,” Barber said. “There’s definitely more research questions that came out of this, as always happens with these types of research studies, I think.”

The local research has also been used to help in other states looking to get ahead of the C. auris outbreak. During the summer of 2022, the study’s researchers collaborated with Utah — which had no C. auris cases at that point — to analyze samples of wastewater there and help monitor the presence of the fungus in Utah communities.

Their joint study compared samples sent from Utah with those drawn from Southern Nevada and found no traces of C. auris in the Utah wastewater.

Crank said that collaboration was so successful that it has led to the development of more with states like Delaware, Hawaii and Arizona. It’s considered a “major move forward” in helping Southern Nevada identify public health problems and develop strategies for them as early as possible.