Diarrhea caused by a slow-growing Enterococcus-like agent in neonatal rats

An enteropathogenic Enterococcus-like agent was isolated from a spontaneous outbreak of diarrhea that occurred in a colony containing neonatal rats. Diarrhea was experimentally reproduced in virus-antibody-free neonatal rats inoculated with this purified "enterococcus." Gram-positive cocci were adhered to the small intestinal villi of affected animals from which the organism was reisolated. The isolate's classification in the genus Enterococcus was confirmed by genetic probe; however, because of its unique fermentation pattern, it could not be definitively speciated. Indirect immunofluorescence assays indicate that this strain of enterococcus and Enterococcus hirae, another strain pathogenic for neonatal rats, differ antigenically. Enterococci should be considered as potential etiologic agents in outbreaks of diarrhea involving neonatal rats and future efforts directed to increasing our understanding of the pathophysiology of this disease.