When taken daily to prevent recurrent urinary tract infections, antibiotics are more effective than daily doses of probiotics, or “good bacteria,” a new study confirms. 

UTIs are a constant threat in nursing homes. The antibiotics used to treat them, such as Bactrim and Septra, often are accompanied by unwanted side effects, such as diarrhea.

To test probiotics as an alternative to antibiotics, researchers from the University of Amsterdam recruited 252 women with a history of recurrent UTIs and divided them into two groups, Reuters reported. One group took a single dose of the antibiotic co-trimoxazole every day for a year; the other group took two capsules containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 daily. 

After a year, 69% of the women taking the antibiotic had one or more UTIs, with an average of 2.9 infections, while 79% of the women taking the probiotics had one or more UTIs, with an average of 3.3 per woman. Researchers did not observe increased resistance to probiotics, which they did with antibiotics. 

The study results appeared in the Archives of Internal Medicine