Anti-toxin antibody is not associated with recurrent Clostridium difficile infection

Abstract

Clostridium difficile infection (CDI) recurs in ∼20% of patients. Prior studies indicated that antibody responses directed against the C. difficile toxins A and B were potentially associated with lower risk of recurrent CDI. Here we tested the hypothesis that circulating anti-toxin IgG antibody levels associate with reduced risk of recurrent CDI. A cohort study with prospective enrollment and retrospective data abstraction examined antibody levels in 275 adult patients at the University of Michigan with CDI. We developed an enzyme linked immunosorbent assay to detect IgG antibodies against toxin A and toxin B in sera obtained at the time of diagnosis. Logistic regression examined the relationship between antibody levels and recurrence, and sensitivity tests evaluated for follow-up and survivor biases, history of CDI, and PCR ribotype. Follow-up data were available for 174 subjects, of whom 36 (20.7%) had recurrence. Comparing antibody levels vs. recurrence and CDI history, anti-toxin A levels were similar, while anti-toxin B levels had a greater range of values. In unadjusted analysis, detection of anti-toxin A antibodies, but not anti-toxin B antibodies, associated with an increased risk of recurrence (OR 2.71 [1.06, 8.37], P = .053). Adjusting for confounders weakened this association. The results were the same in sensitivity analyses. We observed a borderline increased risk of recurrence in patients positive for anti-toxin A antibodies, and sensitivity analyses showed this was not simply a reflection of prior exposure status. Future studies are needed to assess how neutralizing antibody or levels after treatment associate with recurrence.

Keywords: Antibodies; Bacterial toxins; Clostridium difficile; Healthcare-associated infections.

Figure 3:

Plate Fill Pattern for Toxin Coating

Figure 4:

Plate Fill Pattern for Sample and Control Additions Note: 40 Samples Total can be run over the 4 plates, in duplicate and with Toxin A and B Ex. Samples 1–20 on Toxin A Plate #1, Samples 21–40 on Toxin A Plate #2, Samples 1–20 on Toxin B Plate #1, and Samples 21–40 on Toxin B Plate #2

Figure 1:

Anti-toxin antibody distributions. 1A: Anti-toxin A antibodies are similarly distributed across all four recurrence status categories. 1B: Anti-toxin B antibodies have similar median values across recurrence status categories, but a wider range of values. More patients fall above the third quartile in those with recurrence. 1C: Anti-toxin A antibody values are similarly distributed across history status categories. 1D: Antibody B antibody values have similar medians across history status categories, though they have a greater range.

Figure 2.

Venn Diagram of Potential Confounders. The left side of the diagram shows the variables that were found to have a significant relationship with the exposures of anti-toxin A antibodies or anti-toxin B antibodies. The right side of the diagram shows the variables that were found to have a significant relationship with the outcome of recurrence. The overlapping middle region of the diagram shows the variables that were significantly associated with both the exposure(s) and the outcome, identifying them as confounders.