Patients on antibiotics are often prescribed probiotics, a mix of bacteria in pill form, that is meant to counter the effect of the antibiotics on their gut flora, and prevent diarrhea and intestinal diseases.
Now, however, scientists from Technion-Israel Institute of Technology and Boston Children’s Hospital say that use of probiotics in hospital intensive care units may lead to blood infections, and that in some cases the risk may outweigh the benefits.
The study, published in Nature Medicine, is based on a collaboration between Technion scientists Prof. Roy Kishony and Dr. Idan Yelin and research groups led by professors Gregory Priebe and Thomas Sandora from Boston Children’s Hospital.
The research also showed that probiotic consumption in intensive care may trigger the growth of bacteria resilient to antibiotics — a process that lessens the effectiveness of medical treatments.
The hypothesis that probiotics may have harmful effects has been raised in the past, but until now no conclusive evidence had proved a causal link between the intake of bacteria and the generation of infection-causing bacteria, the Technion said in a statement.
By using advanced whole-genome mapping technology, the Technion and Boston Children’s Hospital scientists showed that in some cases, the probiotic bacteria administered to the patient find their way into the bloodstream and cause an infection.
The research is based on data collected over a 5.5-year period from patients at Boston Children’s Hospital’s Intensive Care Unit. During this period, the ICU treated 22,174 patients, of whom 552 received probiotic capsules as part of their treatment. These consisted of Lactobacillus rhamnosus bacteria.
During the study, six patients were diagnosed with Lactobacillus rhamnosus blood infections. All of them were part of the group that received probiotic treatments. Among the thousands of patients who did not receive probiotics, none was diagnosed with this type of blood infection, the study showed.
In their work, the researchers used innovative genomic tools to prove that the infection-causing bacteria originated in the probiotic medication. The DNA sequences of the bacteria from the infections were fully extracted at the Technion Genome Center, along with the DNA of bacteria from the probiotic capsules, and analysis showed that the two were connected.