No Relationship Between Recurrent C Diff and Anti-Toxin Antibodies

The investigators called their findings the “opposite of what was expected.”

Anti-toxin A or B antibodies were not associated with recurrent Clostridium difficile (C diff) infection, according to a paper published in the journal Anaerobe.

Investigators from the University of Michigan retrospectively examined 275 adults with C diff infection in order to determine if the risk for recurrent C diff infection could be reduced if there were anti-toxin antibodies discovered in a serum sample within 48 hours of an index C diff episode.

Patients admitted to Michigan Medicine between January and September 2016 were eligible for the study and the investigators studied their electronic health records, demographics, medial history, vital signs, and laboratory test results (only those conducted within 48 hours before and after C diff sample was gathered).

Of the 275 individuals included, 101 patients had no additional data in their electronic health record and were not included, and a further 138 did not experience C diff recurrence. Thus, the study authors found that 36 did experience C diff recurrence.

The researchers did not report any significant difference in age at C diff diagnosis or proton pump inhibitor exposure status in the patients with and without recurrence.

However, there was a difference between the cohort that experienced recurrence, and those who did not in terms of exposure to high-risk antibiotics. The study authors noted that history of C diff was not different between these groups, but history of ulcerative colitis was different between the groups. Having ulcerative colitis increased the odds of recurrence, the study authors learned.

There were 193 patients with anti-toxin A antibody, of which 96 did not experience recurrent C diff infection and 31 who did. The study authors called this the “opposite of what was expected.”

The study authors said anti-toxin A antibodies “approached significance” in comparison to anti-toxin B antibodies in predicting C diff infection recurrence. There were 213 patients with anti-toxin B antibody exposure, the study authors said, of which 108 did not experience recurrent infection and 29 did experience recurrent infection.

Another notable factor the investigators highlighted is that 20 patients were deceased prior to the end of the recurrence period. Therefore, they said, it is unknown if they would have had recurrent infection if they had survived.

“Prior C diff infection is a known risk factor for recurrent C diff infection,” the study authors concluded. “We speculated that the observed association may have been due to the positive signal acting as a mediator between history of C diff infection and recurrence. Yet, when adjusting the model to include prior history of C diff infection, the increased risk of recurrence remained. Our interpretation of this is that while anti-toxin A antibodies were more likely to be present in those patients with a history of exposure to toxigenic C. difficile, there was no evidence of protection against subsequent C diff infection in this study.”

Prior research into this topic has been published nearly 2 decades ago, the study authors said, a time period in which the epidemiology of C diff infection was different compared to today. Therefore, the study authors suggested that future research could explore C diff infection strain type more specifically compared to a ribotype, because that information could be added to this prediction model of recurrence.