A New Technique for Isolating Listerellae from the Bovine Brain

Abstract

Listerella monocytogenes was isolated from the brain in only 2 of the 5 listed cases on initial culture. After the brain suspensions which were negative on culture had been refrigerated for from 5 wks. to 3 mos., all suspensions yielded the microorganism. The exact mechanism involved has not as yet been determined but reference is made to the possibility of the presence of an inhibitory factor in the bovine brain. A method of readily identifying colonies of Lister ella by use of a dissecting microscope and obliquely transmitted light is described. Identification of the cultures was con- firmed by biochemical reactions and the ability to produce a conjunctivitis when instilled into the eye of a rabbit. A true case of encephalitis in the rabbit resulting from ocular instillation was also reported.