Bacteria present in the gut may predict a patient’s risk for life-threatening blood infections after high-dose chemotherapy.1

High-dose chemotherapy is administered to approximately 20 000 cancer patients each year in preparation for bone marrow or stem cell transplants. Twenty percent to 40% of these patients typically develop blood infections after the chemotherapy, and 15% to 30% of those patients die due to the infections.

Inflammation of the gastrointestinal tract, or mucositis, may be responsible for bacteria infecting the bloodstream during high-dose chemotherapy. Because the chemotherapy depletes the immune system, patients are unable to fight off the infection once it begins and antibiotics often do not work.

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In this study, fecal samples were collected from 28 patients with non-Hodgkin lymphoma before they started chemotherapy. Their bacterial DNA was sequenced to measure the health of the bacterial ecosystem in each patient’s gut.

After their chemotherapy, 11 of the 28 study participants acquired a bloodstream infection. These patients were found to have significantly different mixtures of gut bacteria than the patients who did not get infections.

The researchers, from the University of Minnesota and Nantes University Hospital in France, created an algorithm that could predict which patients were likely to develop a bloodstream infection with approximately 85% accuracy.

“This method worked even better than we expected because we found a consistent difference between the gut bacteria in those who developed infections and those who did not,” said Dan Knights, PhD, an assistant professor at the University of Minnesota Department of Computer Science and Engineering and the Biotechnology Institute, and a coauthor of the study.

“This research is an early demonstration that we may be able to use the bugs in our gut to predict infections and possibly develop new prognostic models in other diseases,” Knights added.

The researchers cautioned that the approach needs to be validated in a larger cohort of patients. The larger study should include patients with different cancer types, different treatment types, and from multiple treatment centers.

“We still need to determine if these bacteria are playing any kind of causal role in the infections, or if they are simply acting as biomarkers for some other predisposing condition in the patient,” said Emmanuel Montassier, MD, PhD, a researcher at the Nantes University Hospital and former researcher at the University of Minnesota, and coauthor if the study.

The study was supported by Nantes University Hospital Grant (BRD/10/04-Q and the Robert Tournut award of the French National Society of Gastroenterology.


1. Mostassier E, Al-Ghalith GA, Ward T, et al. Pretreatment gut microbiome predicts chemotherapy-related bloodstream infection [published online ahead of print April 28, 2016]. Genome Med. doi:10.1186/s13073-016-0301-4.