Strains of C. difficile from piglets are quite uniform genetically, which suggests that a single immunoprophylactic product, when developed, will be effective across the industry. Furthermore, the genetic differences between porcine and human strains imply that porcine infections need not be considered a potential food safety problem.
Successful development of immunoprophylactic products will likely have to be based on including more toxoid in the vaccines. Autogenous vaccination may be effective (since all autogenous products are likely to be different), but there are probably significant challenges for producers of such biologicals.
Nontoxigenic strains of C. difficile seem to function somewhat like a probiotic; when they become established in the intestine early in life, toxigenic strains are excluded. This is in keeping with findings in hamsters and currently under development for use in humans. Competitive exclusion will need further work, but may represent a simple and cost-efficient means for lessening the impact of CDAD on pig production.
