All of the following are true regarding Tyzzer's Disease:
A. The causative agent is a gram-negative, spore-forming rod that propagates only in living cells. B. The organism may survive in the sporulated state in contaminated bedding for at least 1 year. C. Outbreaks in mice are usually characterized by low morbidity and high mortality. D. The organism invades intestinal mucosal epithelium and disseminates to other organs, particularly liver and heart, E. Nude mice are as resistant as immunocompetent mice, so resistance is due in part to B-lymphocyte function.