Development of a new serological assay for the diagnosis of Clostridium difficile infections with prognostic value

The most common hospital-acquired enteral infection is caused by Clostridium difficile. Unfortunately, Clostridium difficile infections (CDI) are of high risk to recur and little is known about how to predict recurrences. Previous findings have shown that high risk for recurrence correlates with low levels of C. difficile toxin-A and -B specific antibodies suggesting the protective role of humoral immunity against bacterial virulence factors. Therefore, the aim of this study was to develop an immunoassay, which specifically measures C.difficile toxin-specific antibodies in the serum that might be correlated with the risk of recurrence. We developed a simple ELISA to measure the quantity of toxin-A and -B-specific antibodies in human serum. The assay was then used to test anti-toxin immune response in healthy controls, in patients with primary CDI and patients with CDI recurrence. The developed assay is simple, reproducible and fast. When using this test in a small clinical trial our results showed a trend toward a higher antibody level in those patients with only one episode of CDI, whereas patients with recurrent CDI had less anti-toxin A or B-specific antibodies in their serum indicating inadequate C. difficile anti-toxin immunity may facilitate recurrent infections. It has already been observed that low antibody levels are associated with recurrent CDI (Bauer et al., 2014). The findings of our clinical trial show a similar trend. Our developed ELISA test could help to conduct further research and it might be helpful in clinical use to detect patients of high risk for CDI recurrence. •Recurrent Clostridium difficile infections (CDI) occurs in up to 65% in certain patient populations•Quantitative testing for antibodies against toxin-A and -B in human serum can be done fast and easy•The test can distinguish between toxin-A and -B immunoreactivity•Patients with a unique CDI episode seem to have higher antibody levels than healthy controls or patients with recurrent CDI