Virulence of El Tor Vibrios for Chick Embryos

Abstract

THE number of tests which can be used with varying degrees of success to differentiate between the two groups of agglutinable vibrios responsible for epidemic cholera, namely, the true or classic Vibrio cholerae and the El Tor vibrios, is steadily mounting. In addition to tests for hæmolytic activity and other alternative procedures such as sublimate precipitation, soda agglutination, heat and chloroform inactivation of agglutinability, and bacteriophage susceptibility (see ref. 1 for earlier literature citations), more recent proposals include direct hæmagglutination of chicken red blood cells in a slide test², growth in trypsin broth and resistance to polymyxin B³, chemical flocculation⁴ and prophage-typing⁵. This communication adds to the growing list another test which may have some biological significance as well as some value as an additional means of differentiating the choleragenic vibrios.