The Demonstration of Phase Variation in Salmonella abortus-equi

The nature of somatic phase variation and its importance in the serological standardisation of O-suspensions of salmonellas for use in the Widal reaction

1.Phase variation of the somatic antigen I inBact. paratyphosumA and of the component XII2inBact. typhosumand British strains ofBact. enteritidishas been confirmed.

2. Strains ofBact. enteritidisisolated in India by blood culture from cases of invasive disease in man fall into two serological types, neither of which undergoes demonstrable somatic phase variation.

3. The probable mechanism of this type of variation is discussed in the light of experimental findings.

4. The effect which phase variation may have on the clarity of end-points in agglutinin titrations and on the serological standardization of Salmonella O-suspensions is demonstrated.

5. The variation is briefly discussed from the points of view of Salmonella philogeny and of human Salmonella infection.

I am indebted to the D.M.S. in India for permission to publish this paper.

Natural occurrence of induced or artificial flagellar antigens in Salmonella newport

Douglas, G. W. (Communicable Disease Center, Atlanta, Ga.), Alma C. McWhorter, and P. R. Edwards. Natural occurrence of induced or artificial flagellar antigens in Salmonella newport. J. Bacteriol. 83:348-350. 1962.-Two epidemiologically related cultures of Salmonella newport, which possessed naturally occurring artificial or induced antigens in phase 2, were studied. It was demonstrated that similar antigens may be obtained by cultivation of normal S. newport cultures in appropriate antisera. These antigens were assigned the symbols 1,12. The diagnostic problems posed by the natural occurrence of induced antigens are mentioned.