Most-at-risk nursing home residents to be tested for superbugs

Apr 17 2007

A Johns Hopkins study of adult patients admitted to The Johns Hopkins Hospital showed that patients who resided in nursing homes or other kinds of long-term care facilities at any time within the last six months were far more likely than other adult patients to carry or be infected with a drug-resistant superbug.

The study, conducted over a four-month period in 2006, was intended to grasp the extent of one of the lesser known hospital superbugs, multidrug-resistant Acinetobacter (MDR-ACIN), and control its spread among the hospital's most vulnerable adult patients. More than 1,600 were screened within 24 hours of admission to any one of five intensive care units where previous infections had been recorded.

Results showed that patients who had been in nursing homes, either admitted to Hopkins directly from a long-term care facility or transferred from home or another community hospital, were 12 times more likely than other patients to be carriers of the bacterium. Rates were even higher, 22 times, among those patients who were wheelchair- or bed-bound because their legs were paralyzed.

As a result of the study, The Johns Hopkins Hospital will begin this summer to test all patients who have spent time in a nursing home, looking for drug-resistant bacteria at the outset of their hospital admission, while also using isolation precautions until their test results are known.

Unless these test results are negative for superbugs, patients are treated as potential carriers. They will receive care only in designated, confined treatment spaces or separate rooms. During treatments, hospital staff are required to wear disposable gloves, masks and gowns, and clean equipment and furniture with strong disinfectants.

The change in procedures related to superbug infection control is designed to prevent spread of highly contagious bacteria that are resistant to many antibiotics, and represents a step up from the current practice in which adult patients in intensive care are screened on admission for the presence of antibiotic-resistant germs but only placed in isolation if tests are positive.

What mostly surprised researchers was that a majority of the MDR-ACIN-colonized patients, who ranged in age from 19 to 74, also carried high rates of three other, more common superbugs. Sixty-two percent had methicillin-resistant Staphylococcus aureus (MRSA), 77 percent had vancomycin-resistant Enterococcus (VRE), and 39 percent had extended-spectrum beta-lactamase (ESBL) gram-negative bacteria.

Hospital epidemiologists in charge of patient safety say their decision to test and isolate such individuals is recognition that safeguards must be tailored to high-risk patient populations in a given community.

“Our best safeguard is to tailor Hopkins' screening and isolation policies to the types of infection in our local population,” says study senior author and hospital epidemiologist Trish Perl, M.D. “Forewarned is forearmed, so by identifying this group of patients as more susceptible to carrying these bacteria, we are better prepared to thwart further spread through early detection, isolation and effective treatment.”

The immediate danger to patients from superbugs is that they can lead to potentially dangerous bloodstream infections, says Perl, a professor of medicine and pathology at The Johns Hopkins University School of Medicine. Perl is past president of the Society of Health Care Epidemiology (SHEA) and will be presenting this week at its annual meeting in Baltimore. More than 300 studies and abstracts from researchers around the world will be discussed at the four-day conference, which focuses on prevention and treatment of infectious diseases in the health care environment.

The researchers' findings, to be presented April 16 at the SHEA meeting, represent the first large-scale survey of Hopkins' adult patients to identify those most at risk of harboring MDR-ACIN, or those at risk of infecting other patients and staff.

No explanation for the high rates was clearly evident from the study, but researchers say the severe underlying illnesses and weakened immune systems in many of the nursing home residents, especially those unable to walk on their own, make these patients prime targets for all kinds of bacteria.

“Our results dramatically illustrate how widespread these drug-resistant bacteria have become among health care facilities in just the last decade,” says Lisa Maragakis, M.D., the hospital epidemiologist who led the investigation. “This is only going to complicate our efforts to get a grip on the problem, and it is going to place added pressure on all hospitals and other health care facilities to increase and fine-tune their surveillance and control measures.”

Maragakis, an assistant professor at Hopkins, points out that of the most widely available drugs used to fight Acinetobacter, frequently only one, Colistin (polymyxin E), is effective against MDR-ACIN. And she says other hospitals have even encountered MDR-ACIN that is also resistant to Colistin, leaving no available treatment options.

All patients infected with MDR-ACIN are put on antibiotic therapy to rid their body of the bacteria. Patients who are carriers, but not infected, do not need this treatment. However, staff must follow the strict isolation precautions for patient care.

Maragakis says hospital outbreaks of MDR-ACIN have become a widespread problem in the last decade. In 2006, the Joint Commission on Accreditation of Healthcare Organizations (now known simply as the Joint Commission) released an estimate that 70 percent of the bacteria that cause infections for 2 million hospitalized Americans each year are resistant to at least one of the drugs most commonly used to treat them.

Researchers say their next steps are to monitor colonization and infection rates over the next year in patients from nursing homes and to identify any other local populations that may also be at higher risk, such as veterans of the war in Iraq, where MDR-ACIN is endemic. They also plan to evaluate bathing practices, such as chlorohexidine washes that destroy any germs on the body surface to see if they are effective at preventing bacterial spread.

Funding for the study was provided by the U.S. Centers for Disease Control and Prevention. Other Hopkins investigators involved in this study were Margaret Gifford; Kathleen Speck; Tracy Ross, B.S., and Karen Carroll, M.D.