Background: Clostridium difficile infection (CDI) is a leading cause of healthcare-related infections in humans, and an emerging pathogen in livestock. Studies have shown that breast fed human neonates have lower rates of carriage of C. difficile compared to formular fed babies, and patients with high serum IgG levels are less likely to develop CDI.
Aim: To develop and evaluate a C. difficile toxoid vaccine for pigs.
Methods: Three gravid gilts received either a toxoid vaccine formulated with C. difficile RT014/020 (A+B+CDT-) or RT237 (A-B+CDT+). Each treatment group was assigned to three control adjuvant injected gravid gilts. Rectal swabs (n=188) were obtained from 12 litters after farrowing. Half of the faecal samples (n=94) were collected on the farrowing day (n=44, treatment group) and a second sampling (n=94) done on day 6. Baseline serum was collected from all gilts before vaccine administration and at farrowing, together with colostrum. Selective toxigenic culture and standard molecular methods were used to detect and characterise C. difficile isolates. To evaluate passive immunotransfer, an ELISA was performed on baseline sera and post-immune sera and colostrum. To determine the association between colonisation and vaccination status, a GEE model was fitted to the data.
Results: The prevalence of C. difficile overall in piglets was 25% (47/188). Progeny of vaccinated gilts were less likely to shed C. difficile on day 6 than day 5 (p < 0.05, GEE). All serum ELISA titres were higher in vaccinees than controls (4128 vs 96; p < 0.05, Wilcoxon rank sum test), but not colostrum ELISA titres (1408 vs 928; p > 0.05, Wilcoxon rank sum test).
Conclusions: This study suggest that passive immuno-transfer could be important in managing C. difficile carriage and infection in piglets. C. difficile carriage in the present study was lower compared to previous studies in the same piggery (25% vs 67%) suggesting that other factors could be at play, such as the use of sporicidal disinfectants.