Antibiotic prophylaxis prevents the development of a post-infectious phenotype in a new rat model of post-infectious IBS.

Background: A recent post-infectious rat model with Campylobacter jejuni 81-176 has replicated the events noted in humans with post-infectious irritable bowel syndrome (IBS). In this study, we test whether prophylactic treatment with the antibiotic rifaximin will prevent the development of long-term altered bowel function in this model.

Methods: Sprague-Dawley rats were divided into two groups. Both groups were gavaged with a 1 mL solution of 10(8) cfu/mL of C. jejuni. However, one group was also prophylactically gavaged with a solution of rifaximin 200 mg per day for 3 days (the day before gavage, the day of gavage, and the day after gavage with C. jejuni). Fresh stool was collected from rats daily until two consecutive stool cultures were negative for C. jejuni. The rats were then housed for 3 months. At the end of 3 months, fresh stool was collected on three consecutive days to determine stool % wet weight and stool consistency on a stool score.

Results: Rats that received rifaximin antibiotic prophylaxis had a greater rate of stool shedding of C. jejuni. However, the mean duration of colonization was shorter in the rifaximin-treated group (10.3 ± 7.1 days) compared to rats receiving no prophylaxis (12.6 ± 5.9 days) (P < 0.01). After 3 months, rats that did not receive rifaximin had a greater variability in stool % wet weight (P < 0.01). Furthermore, the average stool consistency over 3 days of measurement was closer to normal in the rifaximin-treated rats, with a consistency of 1.1 ± 0.3, compared to 1.5 ± 0.4 in rats receiving no prophylaxis (P < 0.00001).

Conclusions: Prophylactic treatment of rats with the antibiotic rifaximin in a new animal model of post-infectious IBS with C. jejuni mitigated the development of long-term altered stool form and function.