January 3, 2018

expert reaction to study looking at dietary trehalose (a sugar additive) and virulence of clostridium difficile infection in a mouse model

Publishing in Nature, researchers have looked at how two strains of the intestinal pathogen Clostridium difficile have acquired the ability to metabolise low levels of trehalose (a sugar additive) in mouse models. They report that this ability correlates with the severity of the disease in the mouse.

Prof. Mark Wilcox, Professor of Medical Microbiology and Sir Edward Brotherton Chair of Bacteriology, University of Leeds, said:

“This is an interesting and well conducted study that suggests that a sugar present in some foods, trehalose, may have played a part in selecting for some more virulent types of C. difficile, a bacterium that came to prominence in the first decade of this millennium as a cause of life-threatening gut inflammation and diarrhoea.  The ‘live’ part of the study was in mice and it is important to know whether the effects seen are replicated in humans.

“It is rarely one attribute only that determines why some bacteria become more successful.  The association that trehalose can be used by virulent types of C. difficile may be one part of the jigsaw explaining why these became more common.  However, the association with trehalose does not explain why the more virulent types of C. difficile increased in countries at different times and then were successfully controlled in some of these, as happened for example in the UK over the last 10 years.  Earlier research has shown that other factors, including the use of particular antibiotics (e.g. fluoroquinolones) that were inactive against virulent types of C. difficile played a key part in their rise to prominence and then their fall.”

Prof. Brendan Wren, Professor of Microbial Pathogenesis and Dean of the Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, said:

“The study offers circumstantial evidence that the increased consumption of the sugar trehalose in food additives is responsible for the increased incidence of highly virulent Clostridium difficile strains that cause severe diarrhea and in some cases death in humans.  The authors demonstrate that selected strains which have spread globally use trehalose as an alternative source of energy which gives them a competitive growth advantage to initiate infection.  The research has been performed on mice and extrapolated to humans based on the historic increase in the use of trehalose in food additives in the early 2000s.  The link cannot be definitively proven, but the study has several lines of independent evidence.

“This study provides a good example of how changes in human activity (e.g. changes in food additives) can have unintended consequences relating to the emergence and ultimately the global spread of an infectious agent.”

* ‘Dietary trehalose enhances virulence of epidemic Clostridium difficile’ by J. Collins et al. was published in Nature on Wednesday 3 January 2018.

Declared interests

Prof. Mark Wilcox: “I have no specific COIs with this subject matter.”

Prof. Brendan Wren: “I have no competing interests.”