May 06, 2016
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Gut microbiota predicts risk for chemotherapy-related BSI

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Examination of pretreatment gut microbiome could identify patients at high risk for bloodstream infection after allogeneic hematopoietic stem cell transplantation, according to a recently published study.

While it is unknown whether the bacteria associated with increased risk for bloodstream infection (BSI) are causative of the condition, the data suggest similar methods of flora identification could be useful for characterizing patient susceptibility to other unexplored conditions.

“We found a consistent difference between the gut bacteria in those who developed infections and those who did not,” Dan Knights, PhD, assistant professor in the computer science and engineering department at the University of Minnesota, said in a press release. “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, Emmanuel Montassier, MD, PhD, researcher at Nantes University Hospital, France, and colleagues collected fecal samples from 28 non-Hodgkin’s lymphoma patients with no history of inflammatory bowel disease, probiotics or broad-spectrum antibiotics. Samples were collected upon admission, before administration of high-dose chemotherapy. From these, researchers amplified 16S ribosomal RNA genes, which then were characterized using high-throughput DNA sequencing. Quantified bacterial taxa were computationally analyzed against the study’s primary endpoint — BSI following hematopoietic stem cell transplantation (HSCT) — to identify potential relationships.

BSIs were reported among 11 patients. Of these, two were Enterococcus BSIs, four were Escherichia coli BSIs and five were other Gammaproteobacteria BSIs.

Principal coordinate analysis showed differences between the fecal samples of patients who did or did not experience BSI (P = .01). More specifically, lower fecal diversity was associated with BSI with reduced evenness (P = .004) and richness (P = .001). In addition, using a novel panel of 13 microbes, the researchers developed a novel risk index able to predict BSI development with 90% sensitivity and 90% specificity. No association was observed between a patient’s clinical history and BSI.

While these findings could suggest the benefit of preventive intestinal microbiota manipulation to reduce BSI risk among immunocompromised patients undergoing HSCT, the researchers noted that more research is necessary to confirm whether such approaches would have an effect on patient outcomes.

“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,” Montassier said in the release. – by Dave Muoio

Disclosure: The researchers report no relevant financial disclosures.