Close to two-thirds of nursing home residents receive antibiotic treatments each year, but a new study suggests inappropriate prescription of antibiotics could carry increased health risks, even for residents who don’t receive them.

Researchers from the University of Toronto found that on average, nursing home residents were prescribed antibiotics on 55 days for every 1,000 days spent in a nursing home facility. The data varied from 20 days to almost 193 days per 1,000 resident days.

The nursing homes studied were split into three categories: low use, medium use and high use, depending on how often they prescribed antibiotics. In high-use facilities, 14% of residents who received antibiotics had an adverse reaction like allergy or diarrhea, compared to 13.5% in medium-use and 12.9% in low-use facilities. Residents who did not receive antibiotics were also at higher risk for antibiotic-resistant infections like C. diff.

“Appropriate antibiotic prescribing may be a particular challenge in the nursing home, though, because histories are difficult to obtain from patients with cognitive impairment, elderly patients often have infection with atypical symptoms such as absence of fever, and there is less access to on-site doctors and laboratory testing,” wrote lead author Dr. Nick Daneman.

Antibiotic stewardship teams who specialize in limiting the adverse effects of antibiotic treatments are becoming increasingly common in acute care hospitals, but are still fairly rare in nursing homes. The University of Pittsburgh recently announced the launch of a three-year national trial that will seek ways to reduce unnecessary antibiotic use in long-term care facilities.