Taking "good" bacteria known as probiotics may help prevent diarrhoea brought on by a tough-to-treat infection that often results from taking antibiotics, according to a fresh look at some past research.
"For older patients that are in hospital or in nursing homes who are exposed to antibiotics, we've shown that certain probiotic regimens at certain dosages result in large reductions in the incidence of C. difficile-associated diarrhoea," said Bradley Johnston, the study's lead author from The Hospital for Sick Children Research Institute in Toronto, Canada.
People who take antibiotics are at risk for losing some of the good bacteria that live in their guts, allowing Clostridium difficile bacteria, or C. difficile, to grow - especially after a stay at the hospital.
The infection's symptoms typically include stomach cramps and diarrhoea. In severe cases, the colon becomes inflamed.
The US Centers for Disease Control and Prevention estimates about 14 000 American die every year from C. difficile-related diarrhoea.
For the new review from the Cochrane Collaboration, an international research organisation that evaluates medical evidence, the researchers analysed data from 23 studies that included 4 213 adults and children taking antibiotics.
The studies that were included in the review split the participants into two groups. One group took probiotics along with their antibiotics, and the other did not. Overall, Johnston and his colleagues found taking probiotics didn't change the number of people who went on to develop C. difficile - about 13% in each group.
It did, however, lead to a significant drop in those who had diarrhoea. The researchers found that only 2% of people who took probiotics developed diarrhoea related to C. difficile. That compared to 6% of people who didn't take probiotics.
'It will hurt your wallet - they're not cheap'
Dr Shira Doron, who was not involved with the new review but studies probiotics, said that the new findings jibe with past research. She said, however, that the results don't apply to all probiotics.
"Every strain (of probiotics) has traits and mechanisms of actions. I think it would be wrong to conclude from the systematic review that you could buy any probiotics off the shelf and take it," said Doron, an associate hospital epidemiologist at Tufts Medical Center in Boston.
Johnston said two of the probiotics that led to the greatest benefit were Saccharomyces boulardii and a combination of Lactobacillus acidophilus and Lactobacillus casei.
Otherwise healthy patients needed at least 10 billion colony-forming bacteria per day to see an effect, he said - the amount in 2-4 pills per day. The price of probiotics varies, but a 30-day supply from the drugstore typically costs about $30.
"What I usually tell patients is that it might help and it's unlikely to hurt. It's generally safe for most patients. It will hurt your wallet - they're not cheap," Doron added.
But she warned that probiotics probably aren't necessary for someone being treated at home for an infection unless they've been in and out of the hospital at some point.
Johnston said it will be important for researchers to do follow-up studies on the safety of probiotics going forward - especially as hospitals start using them.