ON THE DESOXYCHOLATE-SENSITIVE STRAINS OF SALMONELLA PULLORUM

Abstract

1. From a group of chickens in the field, desoxycholate-sensitive strains (DC^s) of Salmonella pullorunz, which did not grow on media ordinarily used for the isolation of the groups of Enterobacteriaceae and containing various dyes or bile salts for selective isolation, were isolated.
2. In morphological, biochemical and serological properties, DC^s strains did not differ from the normal desoxycholate-resistant (DC^r) strains, which are commonly isolated in the field. Serologically, they belonged to the intermediate type, and tests for S-R variation was confirmed as the smooth form.
3. Dissociation of DC^r from DC^s occurred at the frequency of about 10^-6.
4. Comparison of pathogenicities revealed no difference between these two strains in mortality rate, survival clays, and proportion of carriers. However, DC^s strains could not be demonstrated in the bile of infected chickens, but they are isolated from the kidney and testis at far higher rate than DC^r.
5. DC^s strains were found highly sensitive to various bile salts, basic dyes, penicillin, erythromycin, chloramphenicol and tetracycline and several anionic and cationic surface active agents.
6. Between DC^s and DC^r, there was a remarkable difference in resistance of cells to desoxycholate. The former was found to be killed easily, resulting in the elution of nucleic acid.