The Dienes (Mutual Inhibition) Test In The Investigation Of Proteus Infections

The technique of performing the Dienes test is described, as well as its application to the investigation of an outbreak of cross-infection with Proteus mirabilis. The test was found to possess a high degree of specificity. The frequency of reactions of identity among 48 proteus isolates obtained from unrelated sources and tested against themselves was 1 in 70, based on a total number of 1128 tests. These 48 isolates could be grouped into 35 “Dienes strains”

Compatible reactions were obtained between strains possessing major H-antigenic differences. This finding indicates that the relation between H-antigenic structure and inhibition in the Dienes test is probably not as close as has been previously suggested.

In a study of children attending hospital for up to 2 yr, strains of proteus repeatedly isolated from a child were almost always compatible with each other in the Dienes test. This indicates that each child retained his or her own strain and that the strains behaved consistently in relation to the Dienes test during the period of the study.

It is concluded that the specificity, reproducibility and simplicity of the Dienes test make it of great value for the detection of cross-infection with proteus, particularly in an ordinary hospital laboratory. The suggestion is made that the Dienes phenomenon could be due to colicine-like substances and that it could form the basis of a typing system.