Hospital emergency rooms can cure what ails an elderly person, but they can also send them home with an unwanted souvenir of their visit: an infection.

A new study suggests emergency departments may be a source of infections for seniors who turn to them for care, and a potential starting point for some of the infectious outbreaks that make their way through long-term care facilities.

Researchers from Montreal and Riviere-du-loup, Que., and from Toronto looked at seniors living in long-term care, comparing infection rates among those who had been recently treated in an emergency department and those who had not.

They found those who had been to Emerg were nearly four times more likely to have a respiratory or gastrointestinal infection in the week after the hospital visit than seniors who had not been to the hospital.

Lead author Dr. Caroline Quach put it another way: There were 8.3 infections per 1,000 patient days in seniors upon their return from the emergency department compared to 3.4 infections per 1,000 patient days in those who didn't go to Emerg.

The study was published Monday in the Canadian Medical Association Journal.

Preventing infections

The findings suggest emergency departments are a source — though not the only source — of infections in seniors in long-term care.

"But it's one you can control for. It's one that is preventable," said Quach, a specialist in pediatric infectious diseases at McGill University and Montreal Children's Hospital.

"You know who went to the emergency room," she explained. "You know when they come back and you're able to take additional precautions for the week upon their return to the long-term care facility — in particular during the winter months."

The study only looked at seniors in long-term care, so it's not clear if the same infection risk exists for seniors living in their own homes.

"It would seem to make sense that they might also be at risk, although one could argue that the risk may be lower for these individuals because non-institutionalized elderly are generally in better shape than those who are institutionalized," said Dr. Andrew Simor of Toronto's Sunnybrook Health Sciences Centre. Simor was also an author of the study.

It has long been known that people who live in long-term care can be a reservoir of antibiotic resistant infections. They tend to spend time in hospitals and take antibiotics more frequently than younger adults, on average. Many hospitals screen patients coming in from long-term care looking to see if they are carrying drug resistant Staph or other such bugs.

And long-term care facilities have known to watch residents returning from a bout as an inpatient, looking for hospital-acquired infections such as C. difficile.

SARS emerged in Toronto ER

But neither side thought much about the emergency room as a source of infection, even though there have been well-publicized outbreaks related to the transmission of bugs in Emerg.

Toronto's SARS outbreak, for instance, began when the dying son of the woman who brought it to the city from Hong Kong went to Scarborough Grace Hospital and inadvertently spread it to a number of elderly patients in the emergency department. The woman died at home.

"Our memories are short," Simor said.

"What is novel and I think we're only now beginning to understand [it], is the risk in emergency departments themselves, even if you actually haven't been on a hospital ward. And I think we're late coming to this realization."

The paper suggests long-term care facilities might consider using infection control precautions for five to eight days after a resident has been to the emergency department. Quach declined to recommend specifics, saying institutions differ and it would be up to them to assess what is most workable for them.

But Simor suggested hospitals too could look at lowering the risk by examining how seniors are handled when they go to the emergency department. Quach said Quebec's institute of public health is working on such a policy document now.

The study was funded by the Canadian Patient Safety Institute, Quebec's health ministry and the Canadian Institutes of Health Research.

Two of the authors reported having received consultancy fees, remuneration for giving lectures or grant funding from pharmaceutical companies.