A Heavily Encapsulated Form of B. typhosus.

Abstract

It has been reported by the authors that if certain strains of B. coli are incubated within a range of temperature of 4 to 17°C, a mucoid growth will appear.

We have utilized similar technic in examining 9 strains of B. typhosus. All of these have been isolated recently from feces or from blood. Petri dishes containing beef-extract agar plus 1% glucose were inoculated by streaking and then were incubated at 14°C. Two of these 9 strains developed growth definitely mucoid in character but the mucilaginous consistency was less marked than that observed with the colon organism in earlier experiments.

Preparations made by Gins'India-ink method revealed long rods surrounded by heavy capsules, although parallel cultures incubated at 37°C. for 48 hours yielded the usual form of the organism which was much shorter and which was provided with much less capsular structure.

It is suggested that this form described by us may be the mucoid type of B. typhosus.