The emergence of more frequent and virulent Clostridium difficile infections (CDIs) has generally been attributed to antibiotic usage. A recent study (J Collins et al Nature 2018; 553, 291–4. doi:10.1038/nature25178) suggests that changes in our diet are a contributing factor as well.
Here we show that two epidemic ribotypes (RT027 and RT078) have acquired unique mechanisms to metabolize low concentrations of the disaccharide trehalose. RT027 strains contain a single point mutation in the trehalose repressor that increases the sensitivity of this ribotype to trehalose by more than 500-fold. Furthermore, dietary trehalose increases the virulence of a RT027 strain in a mouse model of infection. RT078 strains acquired a cluster of four genes involved in trehalose metabolism, including a PTS permease that is both necessary and sufficient for growth on low concentrations of trehalose. We propose that the implementation of trehalose as a food additive into the human diet, shortly before the emergence of these two epidemic lineages, helped select for their emergence and contributed to hypervirulence.
From GI & Hepatology News: Food additive makes C difficile more virulent: “Prior to 2000, trehalose was limited by a relatively high cost of production.” However, with innovations in production, trehalose concentrations in food increased, particularly in ice cream, pasta, and ground beef; “concentration in food skyrocketed form around 2% to 11.25%.” In addition, the FDA in 2000 noted that trehalose as “generally recognized as safe.”
My take: “On the basis of these observations, we propose that the widespread adoption and use of the disaccharide trehalose in the human diet has played a significant role in the emergence of these epidemic and hypervirulent strains,” Dr. Collins and his colleagues wrote in Nature.