RAPID TEST FOR THE IDENTIFICATION OF ALL SEROTYPES OF VIBRIO-CHOLERAE (INCLUDING NON-AGGLUTINATING VIBRIOS)

A slide-agglutination test (PH test) for the identification of all O serotypes of Vibrio cholerae (particularly NAG vibrios) has been developed. The reaction involves the flagellar H-antigen complex which is a species characteristic in vibrios. The novel feature of the test is cell sensitisation by 1.5% phenol which is incorporated in the saline used to make suspensions. Phenol treatment increases H but reduces O sensitivity without affecting gross cell morphology. It is suggested that this low concentration of phenol causes damage to the outer envelope membrane which normally covers the flagellum and acts as a barrier to H antibody in the living vibrio. The species-specificity of the PH test with H antiserum has been established with 96 cultures of V. cholerae and allied species. Of the 53 cholera and NAG vibrios, 52 reacted positively, the sole exception being an auto-agglutinable strain. None of the 43 control cultures reacted. The success rate was therefore greater than for conventional bacteriological tests. The test was equally effective with stock cultures or unknown freshly isolated strains from several sources. Unabsorbed, whole-cell (OH) antiserum was also used successfully, and this simplification is recommended for routine use. The advantages of the PH test in clinical work are the ease and rapidity with which it enables NAG serotypes to be identified.