Multidrug-resistant pathogens living on the skin spread widely in nursing homes

Researchers from the National Institutes of Health (NIH) and their colleagues identified multidrug-resistant pathogens on the skin of residents in nursing homes. They found that these potentially dangerous microbes spread widely among residents, indicating a need for improved testing and infection control measures to protect people in nursing homes and other vulnerable populations.

“Since the COVID-19 pandemic, we’ve become more aware of nursing homes as part of health care ecosystems, but there hasn’t been much research done in nursing homes about how infections spread in these environments,” said Julie Segre, Ph.D., an investigator at NIH’s National Human Genome Research Institute (NHGRI) and co-senior author of the study published in Nature.

The researchers focused on a nursing home in the Chicago area that — despite following testing and isolation protocols — reported transmissions of Candida auris, a fungus that can cause life-threatening infections. These infections are of growing concern, according to the Centers for Disease Control (CDC), because of this fungus’s frequent resistance to anti-fungal medicines.

The researchers sequenced DNA from skin swabs taken from six different sites on the bodies of 40 residents in the nursing home. In addition to Candida auris, the researchers identified multidrug-resistant bacteria known as “ESKAPE pathogens” living on the residents’ skin. These include bacteria that can cause serious infections such as Escherichia coli and Staphylococcus aureus. DNA sequencing indicated more than half of the residents sampled had at least two ESKAPE pathogens present on their skin and antibiotic-resistance genes were present among these microbes.

Since the COVID-19 pandemic, we’ve become more aware of nursing homes as part of health care ecosystems, but there hasn’t been much research done in nursing homes about how infections spread in these environments.

Although these pathogens can cause life-threatening infections — especially among already vulnerable populations — they can also live harmlessly on the body, meaning these pathogens can spread between residents undetected. The researchers were able to gain a more holistic picture of the microbial communities and how they transfer between people by sampling six sites across each resident’s skin.

“Traditionally, testing procedures only sample one site on the body, but our results suggest this may be insufficient,” said Mary Hayden, M.D., a professor and infectious disease specialist at RUSH University Medical Center in Chicago and a co-senior author of the study. “Sampling multiple sites allows us to capture a variety of microbial strains, which may reveal important linkages in the spread of these organisms.”

The researchers traced how these microbes spread between individuals by analyzing the unique genetic makeup of each strain. If two individuals have microbes that are genetically very similar, one person likely spread the microbe to the other, but if the microbes are genetically distinct, it’s more likely that each person picked up their microbes from an outside source.

The researchers detected both clusters of transmissions and unique strains. Unsurprisingly, strains were often shared between roommates, but the researchers also found evidence of wider spread across the nursing home.

To determine whether other nursing homes might have a similar spread of Candida auris and ESKAPE pathogens, the researchers analyzed data from seven nursing homes in three other states. These data were more limited but still showed evidence of strain sharing in the majority of nursing homes.

“Compared to the gut microbiome, people are often less aware of the microbes on the skin, but these microbes can be transferred, especially in environments such as nursing homes, where one worker typically provides hands-on care to several residents,” said Dr. Segre. “The movement of these microbes between residents could be reduced by measures such as more frequent handwashing.”

According to a CDC report, infections from drug-resistant pathogens increased over 20% in hospitals during the COVID-19 pandemic. Residents from nursing homes often come to hospitals and other medical facilities as their care needs change, bringing the microbes on their skin with them. Implementing procedures to mitigate the spread of these organisms in nursing homes not only protects residents but may be a tool to more widely prevent deadly infections.