Diagnosis of proliferative enteritis in frozen and formalin-fixed, paraffin-embedded tissues from a hamster, horse, deer and ostrich using a Lawsonia intracellularis-specific multiplex PCR assay.

Proliferative enteritis (PE) is an enteric disease that has been reported in a variety of animals. It is caused by an obligate intracellular bacterium identified in swine as Lawsonia intracellularis. The organism can be detected ante-mortem in swine with PE using molecular diagnostic methods. The disease can be diagnosed post-mortem in all species by gross examination of tissues and special histologic staining procedures. In this study we extracted total DNA from frozen or formalin-fixed, paraffin-embedded tissues from cases of pig, hamster, horse, deer and ostrich PE. The samples were subjected to a multiplex PCR reaction using primers specific for a swine isolate of L. intracellularis. Identical sized PCR products were detected in samples from all animals with PE and the specificity of the PCR reaction for L. intracellularis was demonstrated by Southern-blotting and hybridization using specific probes. These results suggest that the intracellular organism of PE in these species are all very closely related to the causative agent of PE in swine, L. intracellularis. In addition, this multiplex PCR assay can be used to detect the organism in frozen or archival tissues, facilitating retrospective diagnosis of PE.