A significant percentage of patients on breathing machines in Maryland hospitals and long-term care facilities are harboring two pathogens known to be deadly for people with weakened immune systems, according to a recent survey conducted by researchers from the University of Maryland School of Medicine.
Nearly 31% of patients receiving breathing support from mechanical ventilators between March and June of this year were found to be colonized with Acinetobacter baumannii, a type of bacteria that can cause infections in patient wounds, blood, urinary tract and lungs.
Another pathogen, Candida auris, was identified in nearly 7% of the 482 patients examined. The fungus can cause severe illness in patients and spreads easily in health care facilities, and is often resistant to treatment with common antifungal medications.
Dr. Anthony Harris, professor of epidemiology and public health at the University of Maryland medical school and the study’s lead author, said that just because a patient tested positive for either pathogen doesn’t mean they were sick with it.
However, he said, the study underscores the importance of bolstering infection control strategies in hospitals and nursing homes alike.
Harris and his colleagues recently published their findings in the Journal of the American Medical Association and presented them at the annual meeting of the Infectious Disease Society of America in Boston. They were the first in the country to conduct a statewide survey of all ventilated patients, and did so with the help of the Maryland Department of Health, Harris said.
Researchers conducted a similar study in 2009, but C. auris only emerged in the country a handful of years ago, Harris said. While A. baumannii has been in the U.S. for more than a decade, it has become increasingly antibiotic-resistant over time.
“We’re lucky in Maryland to have the resources to undertake this type of study,” Harris said.
He leads the Maryland medical school’s Division of Genomic Epidemiology and Clinical Outcomes, which is one of 11 U.S. centers of excellence in hospital infection control designated by the Centers for Disease Control and Prevention. Another is located at Johns Hopkins University, also in Baltimore.
While the CDC marked both C. auris and A. baumannii as “emerging pathogens” that present a threat to global health — and provided the funding for the Maryland survey — more research is sorely needed, Harris said. He urged other states to conduct similar surveys to better understand the prevalence of the pathogens in their hospitals and nursing homes.
Last year, state and local health departments reported 2,377 clinical cases of C. auris around the country — a significant jump from 2019, when there were fewer than 500 cases, according to the CDC. Forty-six cases were identified in Maryland alone. Nearly half of patients who become infected with C. auris die within 90 days, according to the CDC.
The number of patients infected with A. baumannii resistant to treatment with antibiotics also has climbed in recent years. There were an estimated 7,500 cases and 700 deaths from the bacteria in 2020 — up from the previous year, but down from 2017.
More studies are needed to determine what percentage of people colonized with C. auris and A. baumannii go on to get sick from the pathogens, Harris said. However, previous research on MRSA — another type of antimicrobial-resistant bacteria — indicates that about 15% of people harboring the pathogen fall ill with the same strain during their hospital stay and upwards of 25% to 30% fall ill over the following year.
“This will be a familiar refrain,” Harris said, “but we need more research dollars.”
Fifty-one Maryland health care facilities participated in the survey conducted earlier this year.
Researchers found that patients in long-term care facilities, like nursing homes, were more likely to be harboring the studied pathogens than those being treated in hospitals. They identified A. baumannii in at least one patient at a third of acute care hospitals and 94% of long-term care facilities.
Researchers found C. auris in nearly 5% of hospitalized patients and 9% of patients in long-term care facilities.
For Dr. Mary-Claire Roghmann, the study highlighted how chronic ventilator units in long-term care facilities are the center of the country’s antibiotic resistance problem.
Patients on these units tend to be more medically vulnerable, which puts them more at risk of getting sick from C. auris or A. baumannii, said Roghmann, professor of epidemiology, public health and medicine at the University of Maryland School of Medicine. She is not one of the study’s authors.
Additionally, she said, patients who need ventilator support are more likely to shuffle between hospital wings and long-term care settings, giving them more opportunities to become exposed to the pathogens or spread them to other patients.
“These types of studies really emphasize that we need to stay one step ahead of the bacteria developing resistance to our commonly used antibiotics,” she said.
A multipronged approach likely will be needed to combat antimicrobial-resistant pathogens, Roghmann said. It’s necessary to control the use of antibiotics — as bacteria can quickly become resistant to medication — and it’s necessary to control transmission of pathogens once they become resistant to treatment.
The coronavirus pandemic reversed much of the country’s progress in suppressing the spread of antimicrobial-resistant pathogens, said Dr. Susan Huang, a professor in the Division of Infectious Diseases at the University of California, Irvine, School of Medicine.
People who normally wouldn’t require medical attention were being treated at hospitals, creating more opportunity for the spread of such pathogens. With so many sick patients, doctors also were prescribing more antibiotics, even though some were likely unnecessary, as COVID-19 is a viral illness, Huang said. Shortages of gowns, gloves and other protective gear also hastened the spread of non-COVID pathogens in nursing homes and hospitals.
But a study published earlier this month — of which Huang was an author — shows that using a special soap called chlorhexidine to clean the skin of nursing home residents prevents serious infections and reduces the amount of antibiotic-resistant organisms in the long-term care facility.
Harris praised Huang’s study and said more research is needed to further determine how to remove antimicrobial-resistant pathogens from patients’ skin, intestinal tracts and respiratory tracts.
What’s also needed, he said, is more coordination between nursing homes and hospitals.
“During COVID, we pretty much learned which masks work and which masks don’t, and which tests work and which tests don’t,” he said. “We shared that information across the facilities, so from a general point of view, all the hospitals in the state of Maryland were doing the same thing.
“We’re not at that point yet for the control of antibiotic-resistant bacteria in terms of knowing what works and what doesn’t work and coordinating those efforts.”
