Diarrhea associated with enterotoxigenic Escherichia coli (ETEC) infection is more severe among individuals with blood type A, based on data from 106 adults exposed to the agent.
The reseachers speculate that the increased severity is related, in part, to the presence of an adhesin molecule known as EtpA, which binds to the surface of the cells and combines with blood group A glycans to promote a more severe infection.
“Our studies suggest that the many ETEC strains that produce the EtpA adhesin may be particularly well equipped to preferentially infect hosts who express A blood group antigen on mucosal surfaces,” wrote, of Washington University, Saint Louis, and his colleagues.
ETEC, associated with choleralike illness, remains a major cause of infectious diarrhea in developing countries. No current vaccine offers significant protection against it, but EtpA may be useful in vaccine development. “More recently discovered virulence factors and an improved understanding of ETEC microbial pathogenesis could offer additional avenues to protect those at highest risk for severe disease and uncover novel molecular targets for future vaccine development,” the researchers said.
In a study published in, the researchers examined blood samples from 106 adults who had participated in previous human infection model studies. The volunteers were challenged with an ETEC strain known as H10407 that was originally isolated from a case of choleralike illness.
Diarrhea was more frequent among A blood type individuals, compared with other types. Individuals with B or O blood types were significantly more likely to have no diarrhea or mild diarrhea after the E. coli challenge, compared with type A individuals (44% vs. 19%).
Overall, significantly more individuals with A or AB blood types developed moderate to severe diarrhea, compared with those with B or O blood types (81% vs. 56%). In addition, significantly more individuals with blood type A needed early initiation of antibiotic therapy, compared with those with B or O blood types (72% vs. 43%).