With most drugs, inappropriate use only threatens the health of the person who takes the medication. But with misuse of antibiotics, the problems that arise — drug-resistant bacteria, C. difficile infections — are not restricted to the people who have been taking the drugs.
"(Nursing) homes with higher use put patients at higher risk," said Dr. Nick Daneman, first author of the study.
"Unlike other medication classes which can harm the individual recipient of that medication, antibiotics have the capacity to do harm even beyond the individual that gets the medication."
Daneman is an adjunct scientist at the Institute for Clinical Evaluative Sciences and an internal medicine physician at Toronto's Sunnybrook Health Sciences Centre. The study was published in the journal JAMA Internal Medicine, a publication of the American Medical Association.
It has been known for some time that long-term care facilities use a lot of antibiotics. Earlier studies have suggested there is a significant amount of overuse in this sector of the health-care system, with potentially between one-third and half of all use being inappropriate or unnecessary.
Residents of these facilities are typically frail elderly people with a variety of ongoing health concerns. They are at the point in life where their immune systems cannot fight off invaders easily.
These people often live in close quarters and are cared for by staff who move from resident to resident. It's a situation that makes for efficient spread of bacteria and other pathogens that cause infections.
For this study, Daneman and his co-authors looked at antibiotic use in 110,656 residents of 607 nursing homes in Ontario in 2010 and 2011. The nursing homes studied were divided into low, medium and high antibiotic-use categories.
The differences were stark: antibiotic prescribing in high-use facilities was 10 times that of low-use homes.
If high-use homes had residents who were significantly sicker and more frail, that might explain their heavy reliance on antibiotics. But the authors also did a comparison of the residents of the various facilities and found there were not major health differences among them.
That suggests the increased use of antibiotics in the high-use homes likely is due to the doctors who are prescribing at those facilities, said infectious diseases expert Dr. Andrew Simor, who was not involved in this study. Simor is head of microbiology at Sunnybrook.
He suggested this information could help change prescribing behaviours; facilities where antibiotic use is higher than the norm could be targeted with programs aimed at minimizing misuse of these critical drugs.
The article, which Simor praised, also drew a line between high antibiotic use and higher rates of negative consequences of antibiotic use.
Those side-effects were things like allergic reactions to antibiotics, developing antibiotic-related diarrhea, contracting C. difficile infection, or becoming infected with a drug-resistant bacteria. Daneman said the adverse events were generally serious enough to send these people to hospital.
"If you live in a high antibiotic-use home versus a low antibiotic-use home, you had 25 per cent increased risk of one of these serious antibiotic-related adverse events," he said.
Because of the way the study was designed the authors could not tell if the antibiotics used were needed in each setting. So they cannot say that the low-use homes had hit the sweet spot for antibiotic use — not too much, but enough.
Still, Simor noted that when hospitals started to develop programs to cut back on unneeded use of antibiotics — it's called antibiotic stewardship — concerns were raised that some people who needed the drugs might not get them. That hasn't proven to be the case, he said.
"So if you feel comfortable translating those findings into a nursing home setting, I think you'll find the same situation is true — that stewardship will not place patients at increased risk for not getting an antibiotic when they need it."